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Confounders
Kinds of Confounders Selected AbstractsA critical evaluation of genomic control methods for genetic association studiesGENETIC EPIDEMIOLOGY, Issue 4 2009Tony Dadd Abstract Population stratification is an important potential confounder of genetic case-control association studies. For replication studies, limited availability of samples may lead to imbalanced sampling from heterogeneous populations. Genomic control (GC) can be used to correct ,2 test statistics which are presumed to be inflated by a factor ,; this may be estimated by a summary ,2 value (,median or ,mean) from a set of unlinked markers. Many studies applying GC methods have used fewer than 50 unlinked markers and an important question is whether this can adequately correct for population stratification. We assess the behavior of GC methods in imbalanced case-control studies using simulation. SNPs are sampled from two subpopulations with intra-continental levels of FST (,0.005) and sampling schemata ranging from balanced to completely imbalanced between subpopulations. The sampling properties of ,median and ,mean are explored using 6,1,600 unlinked markers to estimate Type 1 error and power empirically. GC corrections based on the ,2 -distribution (GCmedian or GCmean) can be anti-conservative even when more than 100 single nucleotide polymorphisms (SNPs) are genotyped and realistic levels of population stratification exist. The GCF procedure performs well over a wider range of conditions, only becoming anti-conservative at low levels of , and with fewer than 25 SNPs genotyped. A substantial loss of power can arise when population stratification is present, but this is largely independent of the number of SNPs used. A literature survey shows that most studies applying GC have used GCmedian or GCmean, rather than GCF, which is the most appropriate GC correction method. Genet. Epidemiol. 2009. © 2008 Wiley Liss, Inc. [source] Correction for pulse height variability reduces physiological noise in functional MRI when studying spontaneous brain activityHUMAN BRAIN MAPPING, Issue 2 2010Petra J. van Houdt Abstract EEG correlated functional MRI (EEG-fMRI) allows the delineation of the areas corresponding to spontaneous brain activity, such as epileptiform spikes or alpha rhythm. A major problem of fMRI analysis in general is that spurious correlations may occur because fMRI signals are not only correlated with the phenomena of interest, but also with physiological processes, like cardiac and respiratory functions. The aim of this study was to reduce the number of falsely detected activated areas by taking the variation in physiological functioning into account in the general linear model (GLM). We used the photoplethysmogram (PPG), since this signal is based on a linear combination of oxy- and deoxyhemoglobin in the arterial blood, which is also the basis of fMRI. We derived a regressor from the variation in pulse height (VIPH) of PPG and added this regressor to the GLM. When this regressor was used as predictor it appeared that VIPH explained a large part of the variance of fMRI signals acquired from five epilepsy patients and thirteen healthy volunteers. As a confounder VIPH reduced the number of activated voxels by 30% for the healthy volunteers, when studying the generators of the alpha rhythm. Although for the patients the number of activated voxels either decreased or increased, the identification of the epileptogenic zone was substantially enhanced in one out of five patients, whereas for the other patients the effects were smaller. In conclusion, applying VIPH as a confounder diminishes physiological noise and allows a more reliable interpretation of fMRI results. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source] An in vitro investigation of the bulk flow of fluid through apical foramina during simulated tooth extraction: a potential confounder in microbiological studies?INTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2001A. Kapalas Aim,The ,pumping action' induced during tooth extraction may cause bacteria suspended in tissue fluids to be transposed from one anatomical compartment to another. Apart from causing bacteraemia, this may lead to inaccuracies in studies evaluating the presence and distribution of bacteria in and around tooth apices. The aim was to investigate the bulk flow of fluid through apical foramina during simulated extraction of teeth in an in vitro model. The influence of the presence or absence of a coronal restoration was also evaluated. Methodology,Twenty extracted single-rooted, human, mature, permanent teeth were used. Standard access cavities were prepared and the root canals located. Standardized micrographs of the apical foramina were obtained and their area (µm2) was calculated by image analysis software. The teeth were then set and sealed into polyvinylsiloxane (rubber base) impression material. Crystal violet dye was inoculated into the coronal half of the root canal system. Tooth extraction movements were simulated in the impression matrix and the leakage of dyes with and without the presence of a coronal restoration was examined. The procedure was repeated, following application of safranin dye in a coronal trough within the simulated rubber base gingival margin at the CEJ. The results were analysed statistically with the independent-samples t -test and the McNemar test. Results,In the absence of a coronal restoration crystal violet leaked out of the apical foramina in 18/20 teeth; conversely safranin leaked into the teeth through the apical foramina in 11/20 cases when applied to the external root surface. In the presence of an intact coronal restoration crystal violet dye leaked out in 6/20 teeth and conversely safranin leaked into 7/20 teeth. The presence of a coronal restoration significantly reduced (P = 0.002) dye leakage out of the root canal system. No associations were found for leakage of dye into the root canal system when applied externally. In addition, the amount of dye leakage was positively correlated with the area of the apical foramen in the presence of a coronal restoration (P = 0.009). Conclusion,The presence of a coronal restoration significantly reduced leakage of dye out of the apical foramen. Microbiological studies on root canals and periapical lesions using extracted teeth should take potential contamination from this source into account. [source] Hospice Usage by Minorities in the Last Year of Life: Results from the National Mortality Followback SurveyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2003K. Allen Greiner MD OBJECTIVES: To examine racial/ethnic variations in rates of hospice use in a national cohort and to identify individual characteristics associated with hospice use. DESIGN: Secondary analysis of the 1993 National Mortality Followback Survey (NMFS), a nationally obtained sample using death certificates and interviews with relatives (proxy respondents) to provide mortality, social, and economic data and information about healthcare utilization in the last year of life for 23,000 deceased individuals. SETTING: Hospice care. PARTICIPANTS: Individuals aged 15 and older who died in 1993. Subjects were included in this analysis if they died of nontraumatic causes (N = 11,291). MEASUREMENTS: Hospice use was dichotomized by proxy responses indicating use or nonuse of home or inpatient hospice services. The percentage of individuals using hospice services in the last year of life was calculated. RESULTS: Unadjusted bivariate results found that African Americans were less likely to use hospice than whites (odds ratio (OR) = 0.59; P < .001) and that those without a living will (LW) (OR = 0.23; P < .001) and without a cancer diagnosis (OR = 0.28; P < .001) were less likely to use hospice. The negative relationship between African Americans and hospice use was unaffected when controlled for sex, education, marital status, existence of a LW, income, and access to health care. Logistic models revealed that presence of a LW diminished the negative relationship between African Americans and hospice use, but the latter remained significant (OR = 0.83; P = .033). A subanalysis of subjects aged 55 and older showed a significant interaction between access to care and race/ethnicity with respect to hospice use (P = .044). Inclusion of income in this multivariable logistic model attenuated the relationship between African-American race/ethnicity and hospice use (OR = 0.77), and the difference between whites and African Americans became only marginally statistically significant (P = .060). CONCLUSION: In the 1993 NMFS, hospice use was negatively associated with African-American race/ethnicity independent of income and access to healthcare. The relationship is not independent of age, insurance type, or history of stroke. For subjects aged 55 and older, access to healthcare may be an important confounder of the negative relationship between African-American race/ethnicity and hospice use. Consistent with previous studies, this analysis found that African Americans were less likely to use LWs than whites. The reduced importance of African-American race/ethnicity on hospice use with the inclusion of presence of a LW in logistic models suggests that similar cultural processes may shape differences between African Americans and whites in advance care planning and hospice use. [source] Fantasy proneness as a confounder of verbal lie detection toolsJOURNAL OF INVESTIGATIVE PSYCHOLOGY AND OFFENDER PROFILING, Issue 3 2010Karen Schelleman-Offermans Abstract This study investigated whether high fantasy-prone individuals have superior storytelling abilities. It also explored whether this trait is related to specific linguistic features (i.e. self-references, cognitive complexity, and emotional words). Participants high (n = 30) and low (n = 30) on a fantasy proneness scale were instructed to write down a true and a fabricated story about an aversive situation in which they had been the victim. Stories were then examined using two verbal lie detection approaches: criteria-based content analysis (CBCA) and linguistic inquiry and word count (LIWC). Irrespective of the truth status of the stories, independent observers rated stories of high fantasy-prone individuals as being richer in all nine CBCA elements than those of low fantasy-prone individuals. Furthermore, overall, high fantasy-prone people used more self-references in their stories compared with low fantasy-prone individuals. High fantasy prones' fabricated stories scored higher on various truth indices than authentic stories of low fantasy prones. Thus, high fantasy-prone people are good in creating a sense of authenticity, even when they fabricate stories. Forensic experts should bear this in mind when they employ verbal lie detection tools. Copyright © 2010 John Wiley & Sons, Ltd. [source] A parallel analysis of individual and ecological data on residential radon and lung cancer in south-west EnglandJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2001Sarah Darby Parallel individual and ecological analyses of data on residential radon have been performed using information on cases of lung cancer and population controls from a recent study in south-west England. For the individual analysis the overall results indicated that the relative risk of lung cancer at 100 Bq m,3 compared with at 0 Bq m,3 was 1.12 (95% confidence interval (0.99, 1.27)) after adjusting for age, sex, smoking, county of residence and social class. In the ecological analysis substantial bias in the estimated effect of radon was present for one of the two counties involved unless an additional variable, urban,rural status, was included in the model, although this variable was not an important confounder in the individual level analysis. Most of the methods that have been recommended for overcoming the limitations of ecological studies would not in practice have proved useful in identifying this variable as an appreciable source of bias. [source] Criteria for confounders in epidemiological studiesJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 1 2002Zhi Geng The paper addresses a formal definition of a confounder based on the qualitative definition that is commonly used in standard epidemiology text-books. To derive the criterion for a factor to be a confounder given by Miettinen and Cook and to clarify inconsistency between various criteria for a confounder, we introduce the concepts of an irrelevant factor, an occasional confounder and a uniformly irrelevant factor. We discuss criteria for checking these and show that Miettinen and Cook's criterion can also be applied to occasional confounders. Moreover, we consider situations with multiple potential confounders, and we obtain two necessary conditions that are satisfied by each confounder set. None of the definitions and results presented in this paper require the ignorability and sufficient control confounding assumptions which are commonly employed in observational and epidemiological studies. [source] Incidence and risk of venous thromboembolism in patients with verified arterial thrombosis: a population study based on 23 796 consecutive autopsiesJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 9 2006Å. ELIASSON Summary.,Background:,The relationship between atherothrombotic disease and venous thromboembolism (VTE) remains unclear. Patients and methods:,In a cohort of 23 796 consecutive autopsies, performed using a standardized procedure and representing 84% of all in-hospital deaths between 1970 and 1982 in an urban Swedish population, we investigated the relationship between verified arterial thrombosis and VTE, with the hypothesis that patients with thrombosis in major artery segments have increased odds of VTE. Results:,We found an increased risk of VTE in patients with arterial thrombosis (Odds ratio; OR adjusted for gender and age 1.4, 95% confidence interval; CI 1.3,1.5) (P < 0.001). Patients with cervico-cranial and peripheral artery thrombosis had an excess risk even when controlling for age and major concomitant diseases. A negative association between coronary thrombosis and VTE in the univariate analysis (OR 0.7; 95% CI 0.6,0.8) (P < 0.001), was less pronounced in the multivariate analysis (OR 0.8; 95% CI 0.7,1.0) (P = 0.016). Conclusions:,A positive association between atherothrombosis and VTE was confirmed, except in patients with coronary thrombosis, where IHD as competing death cause is a possible confounder. Our findings indicate a potential for directed prevention, but may also imply similarities in etiology. [source] Gender-incompatible liver transplantation is not a risk factor for patient survivalLIVER INTERNATIONAL, Issue 2 2009Frank Lehner Abstract Background/Aims: Clinical data may be suggestive for differences in patient survival in gender-incompatible orthotopic liver transplantation (OLT), but findings are inconsistent and are putatively linked to circulating hormones. We therefore investigated patient survival as well as metabolism of steroids to identify possible causes of improved graft survival in gender-mismatched OLT. Methods: We examined our single-centre database of 1355 recipients of first liver transplants for overall patient survival by non-parametric and parametric analysis of multivariance taking the age of recipient and donor, ischaemia time, underlying liver disease and the time period of transplantation into account. Furthermore, the metabolism of androgens in gender-incompatible OLT was studied in cultures of primary human hepatocytes obtained from male and female patients. Results: Unlike previous studies we were unable to determine overall significant differences in patient survival in gender-incompatible OLT, even though a statistically significant improved patient survival was observed when male donor livers were transplanted into female recipients in univariant analysis (P=0.047). However, when the overall patient management was taken into account no difference in survival was determined in multivariant analysis. Importantly, the metabolism of testosterone did not differ between male and female hepatocyte cultures, except for the production of 6-,-hydroxy-testosterone (P<0.001). Conclusions: Taken collectively, clinical observations may tend to suggest a slightly improved patient survival in gender-incompatible OLT but this cannot be explained on the bases of androgen metabolism. Overall, we view gender-incompatible liver transplantation not to be a confounder in patient survival after OLT. [source] Ratio of myeloid and plasmacytoid dendritic cells and TH2 skew in CRS with nasal polypsALLERGY, Issue 1 2010H. Kirsche Abstract Background:, The role of myeloid and plasmacytoid dendritic cells and its consequences for the TH2 skew in chronic rhinosinusitis (CRS) with nasal polyps (CRSNP+) should be detailed. Methods:, In 18 CRS patients without nasal polyps (CRSNP,), 35 CRSNP+ patients and 22 patients with nasal structural abnormalities without rhinosinusitis (controls), dendritic cells (DC) were differentiated into myeloid (mDC) and plasmacytoid (pDC) subtypes using an antibody cocktail including CD1c (BDCA-1) and CD303 (BDCA-2) in peripheral blood mononuclear cells (PBMC) and single cell preparations of sinonasal mucosa by flow cytometry. Moreover, cells were analysed for expression of CD45, CD3, CD4, CXCR3 (TH1) and CCR4 (TH2) and IFN-,, IL-5, TGF-,1, TGF-,2, ECP and total IgE in nasal secretions were determined. As a possible confounder, Staphylococcus aureus in nasal lavages was detected. Results:, The tissue mDC/pDC-ratio was 1.7 (1.0,2.4) in controls, 3.0 (1.8,4.0) in CRSNP, and 0.8 (0.6,1.0) in CRSNP+ (P < 0.01). In tissue samples, the TH1/TH2 ratio was 12.6 (6.4,16.0) in controls, 12.5 (6.9,21.2) in CRSNP, and 1.8 (1.3,3.6) in CRSNP+ (median and interquartile range, P < 0.001). Less pronounced differences were found in PBMC. S. aureus detection rates or TGF-, levels did not differ between patient groups and S. aureus detection had no influence on the parameters investigated. Conclusion:, A significant TH2 skew in CRSNP+ could be confirmed on the cellular level. It was driven by low myeloid dendritic cell numbers. The TH2 skew did not correlate with S. aureus detection. The data support the concept that CRSNP+ and CRSNP, are pathophysiologically distinct. [source] Contribution of functional variation in the IL13 gene to allergy, hay fever and asthma in the NSHD longitudinal 1946 birth cohortALLERGY, Issue 8 2009S. Black Background:, Genetic variants of the two adjacent genes, IL13 and IL4 have frequently been reported as being associated with susceptibility to atopy and asthma, both in adults and children, and some studies also suggest association with lung function and chronic obstructive pulmonary disease. Methods:, In this study, we examined for the first time the effect of these variants in 2918 adults in a longitudinal birth cohort, the British National Survey of Health and Development, where there are extensive life style, developmental and environmental data. We examine two IL13 single nucleotide polymorphisms (SNPs) IL13 rs20541 (R110Q) and rs1800925 (,1024C>T) and one IL4 SNP, rs2070874 (,33C>T) with likely function. Results:, We show that IL13 rs20541 and rs1800925 are each significantly associated with self-reported asthma and allergy, and that this association is not confounded by any of the known developmental and environmental risk factors for asthma and atopy, including in particular place of birth. IL13 rs20541 does however act as a confounder for the IL13 rs1800925 associations, meaning that there is no statistical support for rs1800925 having an independent effect. There is nevertheless evidence for interaction between smoking and rs1800925, with allergy as outcome. None of the SNPs showed association with measures of lung function, nor any interaction with the effect of smoking on lung function. Conclusion:, In a longitudinal population cohort we have established a role for polymorphism of IL13 in determining susceptibility to both atopy and asthma. [source] Insights into different results from different causal contrasts in the presence of effect-measure modification,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 10 2006Til Stürmer Abstract Purpose Both propensity score (PS) matching and inverse probability of treatment weighting (IPTW) allow causal contrasts, albeit different ones. In the presence of effect-measure modification, different analytic approaches produce different summary estimates. Methods We present a spreadsheet example that assumes a dichotomous exposure, covariate, and outcome. The covariate can be a confounder or not and a modifier of the relative risk (RR) or not. Based on expected cell counts, we calculate RR estimates using five summary estimators: Mantel-Haenszel (MH), maximum likelihood (ML), the standardized mortality ratio (SMR), PS matching, and a common implementation of IPTW. Results Without effect-measure modification, all approaches produce identical results. In the presence of effect-measure modification and regardless of the presence of confounding, results from the SMR and PS are identical, but IPTW can produce strikingly different results (e.g., RR,=,0.83 vs. RR,=,1.50). In such settings, MH and ML do not estimate a population parameter and results for those measures fall between PS and IPTW. Conclusions Discrepancies between PS and IPTW reflect different weighting of stratum-specific effect estimates. SMR and PS matching assign weights according to the distribution of the effect-measure modifier in the exposed subpopulation, whereas IPTW assigns weights according to the distribution of the entire study population. In pharmacoepidemiology, contraindications to treatment that also modify the effect might be prevalent in the population, but would be rare among the exposed. In such settings, estimating the effect of exposure in the exposed rather than the whole population is preferable. Copyright © 2006 John Wiley & Sons, Ltd. [source] Weaknesses of goodness-of-fit tests for evaluating propensity score models: the case of the omitted confounder,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 4 2005Sherry Weitzen PhD Abstract Purpose Propensity scores are used in observational studies to adjust for confounding, although they do not provide control for confounders omitted from the propensity score model. We sought to determine if tests used to evaluate logistic model fit and discrimination would be helpful in detecting the omission of an important confounder in the propensity score. Methods Using simulated data, we estimated propensity scores under two scenarios: (1) including all confounders and (2) omitting the binary confounder. We compared the propensity score model fit and discrimination under each scenario, using the Hosmer,Lemeshow goodness-of-fit (GOF) test and the c-statistic. We measured residual confounding in treatment effect estimates adjusted by the propensity score omitting the confounder. Results The GOF statistic and discrimination of propensity score models were the same for models excluding an important predictor of treatment compared to the full propensity score model. The GOF test failed to detect poor model fit for the propensity score model omitting the confounder. C-statistics under both scenarios were similar. Residual confounding was observed from using the propensity score excluding the confounder (range: 1,30%). Conclusions Omission of important confounders from the propensity score leads to residual confounding in estimates of treatment effect. However, tests of GOF and discrimination do not provide information to detect missing confounders in propensity score models. Our findings suggest that it may not be necessary to compute GOF statistics or model discrimination when developing propensity score models. Copyright © 2004 John Wiley & Sons, Ltd. [source] Antihypertensives and myocardial infarction risk: the modifying effect of history of drug usePHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 4 2001Chantal Bourgault PhD Abstract Purpose Confounding by indication is common in observational studies of outcomes that treatment is intended to affect. In light of the stepped-care approach to hypertension management, we reexamined the controversy around myocardial infarction (MI) risk in relation to antihypertensive agents by considering past drug history both as a confounder and as an effect modifier. Methods Case,control design nested within a cohort of 19,501 adults initiating therapy with angiotensin-converting enzyme inhibitors (ACEI), calcium channel blockers (CCB) or ,-blockers in Saskatchewan (1990,93) and followed up to 1997. MI cases were identified using death certificates and hospital discharge diagnoses (ICD-9 410). Four controls were matched to each case to account for duration and timing of follow-up. Results 812 MI cases were identified, of which 26% were fatal. At first, current use of CCB and ACEI (versus ,-blockers) appeared to be associated with an increased risk of MI (RR,=,2.2; 95% CI,=,1.8,2.7 and RR,=,1.3; CI,=,1.0,1.6 respectively). Adjustment for drug use history attenuated both associations (RR,=,1.6; CI,=,1.1,2.2 and RR,=,1.0; CI,=,0.7,1.4). Moreover, the risk for CCB use disappeared when restricted to patients who had already used these agents in the past (RR,=,1.1; CI,=,0.77,1.7) whereas a high risk of MI for ACEI was found in digoxin users (RR,=,9.4; CI,=,3.2,27.5). Conclusion Past drug history can be both a confounder and an effect modifier in observational studies. We found adjustment for medication history to attenuate the associations between antihypertensive agents and MI risk. In addition, the estimates significantly varied across drug history profiles thus suggesting the presence of preferential prescribing of specific drug classes to high-risk patients. Copyright © 2001 John Wiley & Sons, Ltd. [source] Prospective studies of exposure to an environmental contaminant: The challenge of hypothesis testing in a multivariate correlational contextPSYCHOLOGY IN THE SCHOOLS, Issue 6 2004Joseph L. Jacobson In this paper, we respond to the criticisms and concerns raised by D.V. Cicchetti, A.S. Kaufman, & S.S. Sparrow (this issue) in their review of the PCB literature, with particular attention to our own research in Michigan. We agree that multiple comparisons and functional significance are issues that would benefit from more discussion. However, because the effects associated with exposure to environmental contaminants are generally subtle, the risk of Type II error would be unacceptably high if researchers were to adopt the authors' recommendation to use a Bonferroni correction. We describe the hierarchical approach we have used to deal with the issue of multiple comparisons, which emphasizes the need to base interpretation on consistent patterns in the data and on replicated findings. The issue of confounding is one that has received considerable attention in the PCB studies and, given that one can never measure every possible confounder, the range of control variables that have been evaluated is impressive. We disagree with the authors' assertion that only standardized test scores are sufficiently reliable for use in these studies; behavioral teratogens often involve subtle effects, which can be identified most effectively by innovative, narrow-band tests that have not yet been normed. Moreover, longitudinal statistical analysis is not necessarily the method of choice for the issues being addressed in this literature. One important new development that Cicchetti et al. fail to note is the emergence of evidence from both the Michigan and Dutch cohorts indicating that breast-fed children are markedly less vulnerable. It is not yet clear to what degree this protective effect is attributable to nutrients in breast milk or to more optimal intellectual stimulation by nursing mothers, or both. However, the discovery of effect modifiers that can explain individual differences in vulnerability marks an important advance in our growing understanding of the teratogenic effects of exposure to environmental contaminants on child development. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 625,637, 2004. [source] COVARIATE-ADJUSTED REGRESSION FOR LONGITUDINAL DATA INCORPORATING CORRELATION BETWEEN REPEATED MEASUREMENTSAUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 3 2009Danh V. Nguyen Summary We propose an estimation method that incorporates the correlation/covariance structure between repeated measurements in covariate-adjusted regression models for distorted longitudinal data. In this distorted data setting, neither the longitudinal response nor (possibly time-varying) predictors are directly observable. The unobserved response and predictors are assumed to be distorted/contaminated by unknown functions of a common observable confounder. The proposed estimation methodology adjusts for the distortion effects both in estimation of the covariance structure and in the regression parameters using generalized least squares. The finite-sample performance of the proposed estimators is studied numerically by means of simulations. The consistency and convergence rates of the proposed estimators are also established. The proposed method is illustrated with an application to data from a longitudinal study of cognitive and social development in children. [source] Parental reported apnoea, admissions to hospital and sudden infant death syndromeACTA PAEDIATRICA, Issue 4 2001EA Mitchell Three studies were undertaken: (i) a nation-wide case-control study for sudden infant death syndrome (SIDS), with 393 cases and 1592 controls, examined the association between parental reported apnoea and SIDS; (ii) a case-cohort study, with 84 cases of parental reported apnoea and 1502 controls, aimed to identify risk factors for apnoea; and (ii) national hospital admission data for ALTE and national SIDS mortality data were compared for the years 1986 to 1994. Parental reported apnoea was associated with a significant increased risk of SIDS [adjusted odds ratio (OR) 1.86; 95% confidence interval (CI) 1.12, 3.09]. The population attributable risk was 8%. There was a significant increased risk for parental reported apnoea in infants who did not die after adjustment for potential confounders with maternal smokers, short gestation and admission to the neonatal unit. There was no association with prone sleeping position, co-sleeping and bottle feeding. The mean annual admission rate for ALTE was 9.4/1000 live births. This did not change significantly over the study period (1986,1994). In contrast, the SIDS mortality rate decreased from over 4/ 1000 to 2.1/1000. Admission rates were higher for Maori infants and boys. Conclusion: It may be concluded that the relationship between parental reported apnoea and SIDS is tenuous. [source] Serum Uric Acid Levels Correlate With Left Atrial Function and Systolic Right Ventricular Function in Patients With Newly Diagnosed Heart Failure: The Hellenic Heart Failure StudyCONGESTIVE HEART FAILURE, Issue 5 2008Christina Chrysohoou MD The authors sought to investigate whether serum uric acid levels are associated with systolic left and right ventricular function, as well as left atrial function in patients with newly diagnosed heart failure. The authors enrolled 106 consecutive patients (mean age 65±13 years). Echocardiographic and biochemical assessment was performed during the third day of hospitalization. Pulsed tissue Doppler imaging of the systolic function of mitral and tricuspid annulus was characterized by the systolic waves (Smv and Stv, respectively), expressed in cm/s, and the left atrial function by the Amv wave. Left atrial kinetics was calculated using an equation. Serum uric acid levels were inversely correlated with Stv (P=.005) and left atrial kinetics (P=.05), after controlling for potential confounders. Uric acid levels appear to be correlated with more impaired right ventricular systolic function and decreased left atrial work in patients with heart failure. [source] Panic disorder and suicidal ideation in primary careDEPRESSION AND ANXIETY, Issue 1 2006Daniel J. Pilowsky M.D., M.P.H. Abstract The purpose of this study was to ascertain whether panic disorder (PD) and suicidal ideation are associated in an inner-city primary care clinic and whether this association remains significant after controlling for commonly co-occurring psychiatric disorders. We surveyed 2,043 patients attending a primary care clinic using the Primary Care Evaluation of Mental Disorders (PRIME-MD) Patient Health Questionnaire, a screening instrument that yields provisional diagnoses of selected psychiatric disorders. We estimated the prevalence of current suicidal ideation and of common psychiatric disorders including panic disorder and major depression. A provisional diagnosis of current PD was received by 127 patients (6.2%). After adjusting for potential confounders (age, gender, major depressive disorder [MDD], generalized anxiety disorder, and substance use disorders), patients with PD were about twice as likely to present with current suicidal ideation, as compared to those without PD (adjusted odds ratio [AOR]=1.84; 95% confidence interval [CI]: 1.06,3.18; P=.03). After adjusting for PD and the above-mentioned potential confounders, patients with MDD had a sevenfold increase in the odds of suicidal ideation, as compared to those without MDD (AOR=7.00; 95% CI: 4.42,11.08; P<.0001). Primary care patients with PD are at high risk for suicidal ideation, and patients with PD and co-occurring MDD are at especially high risk. PD patients in primary care thus should be assessed routinely for suicidal ideation and depression. Depression and Anxiety 23:11,16, 2006. © 2005 Wiley-Liss, Inc. [source] A register study of the impact of stopping third trimester selective serotonin reuptake inhibitor exposure on neonatal healthACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2010W. Warburton Warburton W, Hertzman C, Oberlander TF. A register study of the impact of stopping third trimester selective serotonin reuptake inhibitor exposure on neonatal health. Objective:, To determine whether risk for adverse neonatal outcomes are reduced by stopping SSRI use before the end of pregnancy. Method:, Using population health data, maternal health and prenatal SSRI prescriptions were linked to neonatal birth records (N = 119 547) (1998,2001). Neonates SSRI-exposed in the last 14 days (L14) of gestation were compared with infants who had gestational exposure, but not during the last 14 days (NL14). Propensity score matching was used to control for potential confounders (total exposure, maternal health characteristics). Results:, Increased risk for neonatal respiratory distress was present where L14 exposure occurred compared with risk where exposure stopped before L14. However, controlling for potential maternal and neonatal confounders, differences disappeared. Conclusion:, Controlling for maternal illness severity, reducing exposure to SSRI's at the end of pregnancy had no significant clinical effect on improving neonatal health. These findings raise the possibility that some adverse neonatal outcomes may not be an acute pharmacological condition such as toxicity or withdrawal. [source] The current status of urban-rural differences in psychiatric disordersACTA PSYCHIATRICA SCANDINAVICA, Issue 2 2010J. Peen Peen J, Schoevers RA, Beekman AT, Dekker J. The current status of urban,rural differences in psychiatric disorders. Objective:, Reviews of urban,rural differences in psychiatric disorders conclude that urban rates may be marginally higher and, specifically, somewhat higher for depression. However, pooled results are not available. Method:, A meta-analysis of urban,rural differences in prevalence was conducted on data taken from 20 population survey studies published since 1985. Pooled urban,rural odds ratios (OR) were calculated for the total prevalence of psychiatric disorders, and specifically for mood, anxiety and substance use disorders. Results:, Significant pooled urban,rural OR were found for the total prevalence of psychiatric disorders, and for mood disorders and anxiety disorders. No significant association with urbanization was found for substance use disorders. Adjustment for various confounders had a limited impact on the urban,rural OR. Conclusion:, Urbanization may be taken into account in the allocation of mental health services. [source] Gender differences in bipolar disorder type I and IIACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2009K. Suominen Objective:, We investigated gender differences in bipolar disorder (BD) type I and II in a representative cohort of secondary care psychiatric in- and out-patients. Method:, In the prospective, naturalistic Jorvi Bipolar Study of 191 secondary care psychiatric in- and out-patients, 160 patients (85.1%) could be followed up for 18 months with a life chart. Results:, After adjusting for confounders, no marked differences in illness-related characteristics were found. However, female patients with BD had more lifetime comorbid eating disorders (P < 0.001, OR = 5.99, 95% CI 2.12,16.93) but less substance use disorders (P < 0.001, OR = 0.29, 95% CI 0.16,0.56) than males. Median time to recurrence after remission was 3.1 months longer among men than women, female gender carrying a higher hazard of recurrence (P = 0.006, HR = 2.00, 95% CI 1.22,3.27). Conclusion:, Men and women with type I and II BD have fairly similar illness-related clinical characteristics, but their profile of comorbid disorders may differ significantly, particularly regarding substance use and eating disorders. In medium-term follow-up, females appear to have a higher hazard of recurrence than males. [source] Maternal fever at birth and non-verbal intelligence at age 9 years in preterm infantsDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 3 2003Olaf Dammann MD MS To test the hypothesis that characteristics of perinatal infection are associated with long-term cognitive limitations among preterm infants, we analyzed data from 294 infants (142 females, 152 males) ,1500g birthweight and <37 completed weeks of gestation who were examined at age 9 years. We identified 47 children (20 females, 27 males) who had a non-verbal Kaufman Assessment Battery for Children (K-ABC) scale standard value below 70, i.e. more than 2 SDs below the age-adjusted mean. The 247 children (122 females, 125 males) with a score ,70 served as control participants. Maternal nationality and education, and low gestational age were significantly associated with a K-ABC non-verbal standard value <70. Both neonatal brain damage (intraventricular hemorrhage) and long-term sequelae (cerebral palsy [CP], diagnosed at age 6 years) were significantly associated with a below-normal non-verbal K-ABC score. Maternal fever at birth was present in five cases (11%) and eight controls (3%; odds ratio 3.6, 95% confidence interval 1.1 to 11.4). Clinical chorioamnionitis and preterm labor and/or premature rupture of membranes (as opposed to toxemia and other initiators of preterm delivery) were also more common among cases than control participants. When adjusting for potential confounders such as gestational age, maternal education and nationality, and CP, the risk estimate for maternal fever remained unchanged (3.8, 0.97 to 14.6). We conclude that perinatal infection might indeed contribute to an increased risk for long-term cognitive deficits in preterm infants. [source] Early neurodevelopmental markers predictive of mortality in infants infected with HIV-1DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2003Antolin Llorente PhD One-hundred and fifty-seven vertically infected HIV-1 positive infants (85 males, 72 females) underwent longitudinal assessment to determine whether early neurodevelopmental markers are useful predictors of mortality in those infants who survive to at least 4 months of age. Survival analysis methods were used to estimate time to death for quartiles of 4-month scores (baseline) on the Bayley Scales of Infant Development (BSID). Cox proportional hazards progression was used to estimate relative hazard (RH, 95% CI) of death for BSID scores and potential confounders. Thirty infants with BSID scores at 4 months of age died during follow-up. Survival analysis revealed greater mortality rates in infants with BSID (Mental Developmental Index and Psychomotor Developmental Index) scores in the lower quartile(p=0.004,p=0.036). Unadjusted univariate analyses revealed increased mortality associated with baseline CD4+ 29%, gestational age <37 weeks, smaller head circumference, advanced HIV and higher plasma viral load. BSID scores independently predicted mortality after adjusting for treatment, clinical category, gestational age, plasma viral load and CD4+ percentage. [source] Platelet hyperactivity in clinical depression and the beneficial effect of antidepressant drug treatment: how strong is the evidence?ACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2004R. Von Känel Objective:, Platelet hyperactivity is thought to contribute to the increased coronary artery disease (CAD) risk in depression. This study reviewed the evidence for hyperactive platelets and for effects of antidepressant drug treatment on platelet ,stickiness' in clinical depression. Method:, By means of PubMed electronic library search, 34 studies in English were identified (1983,2003) and critically reviewed. Results:, In depression, flow cytometry studies allowing detection of subtle platelet activation states consistently found at least one platelet activation marker to be increased, while the bulk of platelet aggregation studies did not suggest increased platelet aggregability. Platelets seem to be more activated in depressed patients with CAD than in depressed individuals without CAD. The selective serotonin reuptake inhibitors normalized platelet hyperactivity in four studies. Conclusion:, Data on platelet activity in depression are inconclusive. To resolve this issue and its clinical implications, studies in larger sample sizes controlling for confounders of platelet functioning and prospectively designed are needed. [source] Charlson Index Is Associated with One-year Mortality in Emergency Department Patients with Suspected InfectionACADEMIC EMERGENCY MEDICINE, Issue 5 2006Scott B. Murray MD Abstract Objectives: A patient's baseline health status may affect the ability to survive an acute illness. Emergency medicine research requires tools to adjust for confounders such as comorbid illnesses. The Charlson Comorbidity Index has been validated in many settings but not extensively in the emergency department (ED). The purpose of this study was to examine the utility of the Charlson Index as a predictor of one-year mortality in a population of ED patients with suspected infection. Methods: The comorbid illness components of the Charlson Index were prospectively abstracted from the medical records of adult (age older than 18 years) ED patients at risk for infection (indicated by the clinical decision to obtain a blood culture) and weighted. Charlson scores were grouped into four previously established indices: 0 points (none), 1,2 points (low), 3,4 points (moderate), and ,5 points (high). The primary outcome was one-year mortality assessed using the National Death Index and medical records. Cox proportional-hazards ratios were calculated, adjusting for age, gender, and markers of 28-day in-hospital mortality. Results: Between February 1, 2000, and February 1, 2001, 3,102 unique patients (96% of eligible patients) were enrolled at an urban teaching hospital. Overall one-year mortality was 22% (667/3,102). Mortality rates increased with increasing Charlson scores: none, 7% (95% confidence interval [CI] = 5.4% to 8.5%); low, 22% (95% CI = 19% to 24%); moderate, 31% (95% CI = 27% to 35%); and high, 40% (95% CI = 36% to 44%). Controlling for age, gender, and factors associated with 28-day mortality, and using the "none" group as a reference group, the Charlson Index predicted mortality as follows: low, odds ratio of 2.0; moderate, odds ratio of 2.5; and high, odds ratio of 4.7. Conclusions: This study suggests that the Charlson Index predicts one-year mortality among ED patients with suspected infection. [source] Brachial-ankle pulse wave velocity and cardiovascular risk factors in the non-diabetic and newly diagnosed diabetic Chinese: Guangzhou Biobank Cohort Study-CVDDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2010Lin Xu Abstract Background Increased arterial stiffness is an important cause of cardiovascular disease (CVD). We examined determinants of arterial stiffness in subjects across strata of glycaemic status. Methods A total of 1249 subjects from a sub-study of the Guangzhou Biobank Cohort Study (GBCS-CVD) had brachial-ankle pulse wave velocity (baPWV) measured by automatic oscillometric method. Major cardiovascular risk factors including glycosylated haemoglobin A1c (HbA1c), high sensitivity C-reactive protein (hsCRP), fasting triglyceride, low- and high-density lipoprotein cholesterol and both fasting and post 2-h oral glucose-load glucose, systolic and diastolic blood pressure were assessed. Results In all, 649, 479 and 121 subjects were classified into normoglycaemia, impaired glucose metabolism (IGM) and newly diagnosed diabetes groups, respectively. Both age and systolic blood pressure were significantly associated with increased baPWV in all three groups (all p < 0.001). In both normoglycaemic and IGM groups, hsCRP and HbA1c were positively associated with baPWV (p from 0.04 to < 0.001), whereas current smoking and triglyceride were associated with baPWV in the normoglycaemic and IGM group, respectively (p = 0.04 and 0.001). No gender difference in baPWV was observed in the normoglycaemic or IGM groups. However, in the newly diagnosed diabetes group, men had higher baPWV than women (p = 0.01). Conclusions In the normoglycaemic and IGM subjects, after adjusting for age, blood pressure and other confounders, increasing HbA1c was associated with increased baPWV, suggesting a pathophysiological role of chronic glycaemia that can contribute to vascular disease risk in persons without diabetes. Copyright © 2010 John Wiley & Sons, Ltd. [source] Interactive effect of central obesity and hypertension on cognitive function in older out-patients with Type 2 diabetesDIABETIC MEDICINE, Issue 12 2008E. Kim Abstract Aim Central obesity, hypertension and diabetes mellitus have been related individually to cognitive dysfunction. We aimed to study the interactive effects of these co-occurring risk factors on cognitive decline, which remain unclear in older patients with diabetes. Methods We assessed metabolic profiles and neuropsychological functions in 60 older out-patients with Type 2 diabetes to examine the associations of central obesity with cognitive functions, while controlling for other confounding factors in these subjects. Results Waist circumference was associated with poor performance in digits forward (r2 = 0.11, P = 0.02), choice reaction time (r2 = 0.08, P = 0.04) and cognitive reaction time (r2 = 0.07, P < 0.05) even after adjustment for potential confounders including age, gender, education and HbA1c. There were also significant interactions between central obesity and hypertension with respect to performance of digits forward (P = 0.04) and delayed verbal cued recall (P = 0.03). Conclusion Our findings suggest that, in addition to glycaemic control, central obesity and hypertension influence cognitive functions, such as attention and psychomotor speed in older patients with Type 2 diabetes. [source] The prevalence of co-morbid depression in adults with Type 2 diabetes: a systematic review and meta-analysisDIABETIC MEDICINE, Issue 11 2006S. Ali Abstract Aim, To conduct a systematic literature review in order to estimate the prevalence and odds ratio of clinically relevant depression in adults with Type 2 diabetes compared with those without. Methods,medline, embase and psycinfo databases were searched using MeSH terms and free text to identify relevant controlled studies. Published reference lists were also examined. Study selection and appraisal were conducted independently by two reviewers and a meta-analysis was performed to synthesize and analyse the data. Results, Ten controlled studies including a total of 51 331 people were published between January 1980 and May 2005. The prevalence of depression was significantly higher in patients with Type 2 diabetes compared with those without [17.6 vs. 9.8%, OR = 1.6, 95%, confidence interval (CI) 1.2,2.0]. However, in most studies, patients with diabetes differed from those without on variables known to be associated with an increased risk of depression. The prevalence of depression was higher in females with diabetes (23.8%) compared with males (12.8%); however, the odds ratio for depression in patients with Type 2 diabetes compared with those without was higher in males (OR = 1.9, 95% CI 1.7,2.1) than females (OR = 1.3, 95% CI 1.2,1.4). Failure to report potential confounders prevented a more rigorous meta-analysis of risk. Conclusion, We identified raised rates of depression in people with Type 2 diabetes, however, there is a need for well-controlled and better-reported studies to inform the development of effective treatments for depression in these patients. [source] A longitudinal observational study of insulin therapy and glycaemic control in Scottish children with Type 1 diabetes: DIABAUD 3DIABETIC MEDICINE, Issue 11 2006Scottish Study Group for the Care of the Young with Diabetes Abstract Objective/background, Our objective was to investigate glycaemic control in children with Type 1 diabetes in Scotland and to analyse the effect of changing ,conventional' insulin regimen strategies on outcome. DIABAUD 2 (1997,1998) (D2) demonstrated that average glycaemic control in young people with Type 1 diabetes in Scotland was poor, with mean HbA1c of 9.0%. Over 90% were then treated with a twice-daily insulin regimen. The aim of DIABAUD 3 (2002,2004) (D3) was to determine if control had improved, and to examine changes in insulin regimen and effects on glycaemic control. Methods, In DIABAUD 3, data were collected prospectively on children aged < 15 years. in nine out of 15 centres throughout Scotland. HbA1c on 986 subjects was measured in a single Diabetes Control and Complications Trial-aligned laboratory. The results were compared with those from DIABAUD 2, for the same nine centres. Multiple regression comparison was performed to adjust for imbalance in relevant confounders (e.g. age, duration, height and weight, insulin dose and centre). Results, For D3, the age range was 1.1,14.9 years (62% aged 10,14 years), mean (± sd) HbA1c 9.2% ± 1.5 (compared with D2, 9.0% ± 1.5). Only 9.7% achieved the target of HbA1c < 7.5%. The number of subjects in D3 on twice-daily injections was 51% (compared with 94% in D2), 43% on three-times-daily injections (2% in D2) and 2.3% on four or more (1.9% in D2): HbA1c did not differ in these groups. In both the D2 and D3 cohorts, HbA1c rose with age. After adjustment for other variables in the combined datasets, insulin regimen was not a significant predictor of HbA1c (F = 0.19, d.f. = 3, 1774; P = 0.90). Conclusion, The glycaemic control in young people in Scotland remains poor and above the national target. Over 4 years, moderate intensification of insulin therapy (i.e. from two to three injections each day, usually reflecting splitting of the evening dose) across the population failed to improve the average HbA1c and reduce the increase seen with age. A national programme away from ,conventional' to an ,intensive' regimen of insulin therapy is required. [source] | |||||||||||||||||||||||||||||||||||||||||||