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Used Logistic Regression (used + logistic_regression)
Terms modified by Used Logistic Regression Selected AbstractsThe transferability of distribution models across regions: an amphibian case studyDIVERSITY AND DISTRIBUTIONS, Issue 3 2009Flavio Zanini ABSTRACT Aim, Predicting species distribution is of fundamental importance for ecology and conservation. However, distribution models are usually established for only one region and it is unknown whether they can be transferred to other geographical regions. We studied the distribution of six amphibian species in five regions to address the question of whether the effect of landscape variables varied among regions. We analysed the effect of 10 variables extracted in six concentric buffers (from 100 m to 3 km) describing landscape composition around breeding ponds at different spatial scales. We used data on the occurrence of amphibian species in a total of 655 breeding ponds. We accounted for proximity to neighbouring populations by including a connectivity index to our models. We used logistic regression and information-theoretic model selection to evaluate candidate models for each species. Location, Switzerland. Results, The explained deviance of each species' best models varied between 5% and 32%. Models that included interactions between a region and a landscape variable were always included in the most parsimonious models. For all species, models including region-by-landscape interactions had similar support (Akaike weights) as models that did not include interaction terms. The spatial scale at which landscape variables affected species distribution varied from 100 m to 1000 m, which was in agreement with several recent studies suggesting that land use far away from the ponds can affect pond occupancy. Main conclusions, Different species are affected by different landscape variables at different spatial scales and these effects may vary geographically, resulting in a generally low transferability of distribution models across regions. We also found that connectivity seems generally more important than landscape variables. This suggests that metapopulation processes may play a more important role in species distribution than habitat characteristics. [source] Richness patterns, species distributions and the principle of extreme deconstructionGLOBAL ECOLOGY, Issue 2 2009Levi Carina Terribile ABSTRACT Aim, To analyse the global patterns in species richness of Viperidae snakes through the deconstruction of richness into sets of species according to their distribution models, range size, body size and phylogenetic structure, and to test if environmental drivers explaining the geographical ranges of species are similar to those explaining richness patterns, something we called the extreme deconstruction principle. Location, Global. Methods, We generated a global dataset of 228 terrestrial viperid snakes, which included geographical ranges (mapped at 1° resolution, for a grid with 7331 cells world-wide), body sizes and phylogenetic relationships among species. We used logistic regression (generalized linear model; GLM) to model species geographical ranges with five environmental predictors. Sets of species richness were also generated for large and small-bodied species, for basal and derived species and for four classes of geographical range sizes. Richness patterns were also modelled against the five environmental variables through standard ordinary least squares (OLS) multiple regressions. These subsets are replications to test if environmental factors driving species geographical ranges can be directly associated with those explaining richness patterns. Results, Around 48% of the total variance in viperid richness was explained by the environmental model, but richness sets revealed different patterns across the world. The similarity between OLS coefficients and the primacy of variables across species geographical range GLMs was equal to 0.645 when analysing all viperid snakes. Thus, in general, when an environmental predictor it is important to model species geographical ranges, this predictor is also important when modelling richness, so that the extreme deconstruction principle holds. However, replicating this correlation using subsets of species within different categories in body size, range size and phylogenetic structure gave more variable results, with correlations between GLM and OLS coefficients varying from ,0.46 up to 0.83. Despite this, there is a relatively high correspondence (r = 0.73) between the similarity of GLM-OLS coefficients and R2 values of richness models, indicating that when richness is well explained by the environment, the relative importance of environmental drivers is similar in the richness OLS and its corresponding set of GLMs. Main conclusions, The deconstruction of species richness based on macroecological traits revealed that, at least for range size and phylogenetic level, the causes underlying patterns in viperid richness differ for the various sets of species. On the other hand, our analyses of extreme deconstruction using GLM for species geographical range support the idea that, if environmental drivers determine the geographical distribution of species by establishing niche boundaries, it is expected, at least in theory, that the overlap among ranges (i.e. richness) will reveal similar effects of these environmental drivers. Richness patterns may be indeed viewed as macroecological consequences of population-level processes acting on species geographical ranges. [source] Multiple pathways for woody plant establishment on floodplains at local to regional scalesJOURNAL OF ECOLOGY, Issue 2 2003David J. Cooper Summary 1The structure and functioning of riverine ecosystems is dependent upon regional setting and the interplay of hydrologic regime and geomorphologic processes. We used a retrospective analysis to study recruitment along broad, alluvial valley segments (parks) and canyon segments of the unregulated Yampa River and the regulated Green River in the upper Colorado River basin, USA. We precisely aged 811 individuals of Populus deltoides ssp. wislizenii (native) and Tamarix ramosissima (exotic) from 182 wooded patches and determined the elevation and character of the germination surface for each. We used logistic regression to relate recruitment events (presence or absence of cohort) to five flow and two weather parameters. 2Woody plant establishment occurred via multiple pathways at patch, reach and segment scales. Recruitment occurred through establishment on (1) vertically accreting bars in the unregulated alluvial valley, (2) high alluvial floodplain surfaces during rare large flood events, (3) vertically accreting channel margin deposits in canyon pools and eddies, (4) vertically accreting intermittent/abandoned channels, (5) low elevation gravel bars and debris fans in canyons during multi-year droughts, and (6) bars and channels formed prior to flow regulation on the dammed river during controlled flood events. 3The Yampa River's peak flow was rarely included in models estimating the likelihood that recruitment would occur in any year. Flow variability and the interannual pattern of flows, rather than individual large floods, control most establishment. 4Regulation of the Green River flow since 1962 has had different effects on woody vegetation recruitment in canyons and valleys. The current regime mimics drought in a canyon setting, accelerating Tamarix invasion whereas in valleys the ongoing geomorphic adjustment of the channel, combined with reduced flow variability, has nearly eliminated Populus establishment. 5A single year's flow or a particular pattern of flows over a sequence of years, whether natural or man-made, produces different recruitment opportunities in alluvial and canyon reaches, in diverse landforms within a particular river reach, and for Populus and Tamarix. The design of flows to restore riparian ecosystems must consider these multiple pathways and adjust the seasonal timing, magnitude and interannual frequency of flows to match the desired outcome. [source] Surface wear of incoloy and darvic bands on Atlantic Puffin adults and chicksJOURNAL OF FIELD ORNITHOLOGY, Issue 2 2006André R. Breton ABSTRACT Bands are a common marking method in bird studies and capture-mark-reencounter (CMR) models are often used to analyze banding data. Common to this family of models are two assumptions: marks do not fall off or become unreadable and individuals within groups remain equally detectable. When data fail to meet these assumptions, results of CMR analyses may be biased. In studies of long-lived seabirds exposed to coarse nesting substrates, band wear is especially problematic. We compared surface wear from abrasion against rocks on incoloy and darvic bands applied to a long-lived seabird, the Atlantic Puffin (Fratercula arctica). In 2003 and 2004, surface wear on bands applied to chicks and adults was scored at five colonies in the Gulf of Maine. We used logistic regression to analyze two subsets of these data by fitting the probability of being worn (one or more characters difficult to read or obliterated) to band age, bird age, and band type. In both analyses, an evidence ratio provided exclusive support for the model that included all factors. Immature puffins largely avoid colonies and remain at sea until their second or third summer after hatching. Consequently, probabilities of being worn were delayed on both band types by 4 yr on bands applied to chicks compared to adults. Based on our estimates, 25% and 87% of darvic bands applied to chicks and adults, respectively, were worn after 5 yr. Wear was reduced by 71% and 87% annually on incoloy compared to darvic bands applied to adults and chicks, respectively. To uphold assumptions of CMR models, we recommend incoloy bands over darvic in studies spanning more than about 5 yr of long-lived seabirds exposed to coarse substrates. SINOPSIS Las anillas colocadas en las patas son un método común de marcar aves y se han establecido modelos (recuento de aves marcadas , siglas en inglés CMR) para analizar los datos obtenidos de esta forma. Hay dos postulados que deben aceptarse en estos modelos: que las anillas no se pierden o que se puedan leer y que los individuos marcados y no-marcados tienen la misma probabilidad de ser contados. Cuando los datos no cumplen con las dos condiciones previamente mencionadas el análisis de CMR puede contener sesgo. En estudios de ave marinas que viven por mucho tiempo, el desgaste de las anillas crea problemas. Comparamos el desgaste y daño de anillas de metal (niquel-cromio y acero) y anillas de plástico (policloruro de vinilo) colocadas en individuos de Fratercula arctica. Durante el 2003 y 2004, estudiamos el desgaste y daño de anillas colocadas a pichones y adultos del ave en cinco colonias de estas en el Golfo de Maine. Utilizamos una regresión logística para analizar dos conjuntos de datos sobre la probabilidad de desgaste (uno o más caracteres en la anilla difíciles de leer) a la edad de la anilla (tiempo en la pata del ave), edad del ave y tipo de anilla. Las aves inmaduras, evitan los grupos en las colonias y permanecen en el mar hasta el segundo o tercer verano. Como resultado, la probabilidad de que ambos tipos de anillas hubieran estado desgastadas o dañadas en los juveniles se dilato por unos cuatro años, al ser este grupo comparado con los adultos. El 25% y el 87% de las anillas plásticas colocadas en pichones y adultos, respectivamente, estaban desgastadas a los cinco años. El desgaste en las anillas de metal se redujo en un 71% y 87% anual al compararse con las plásticas colocadas en adultos y pichones, respectivamente. Para cumplir con los postulados de los modelos CMR, recomendamos el uso de anillas de metal en aquellos estudios pautados para más de cinco años particularmente en aves marinas que utilizan o se exponen a sustratos duros. [source] Body mass index in adults with intellectual disability: distribution, associations and service implications: a population-based prevalence studyJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 4 2008S. Bhaumik Abstract Background Previous studies of weight problems in adults with intellectual disability (ID) have generally been small or selective and given conflicting results. The objectives of our large-scale study were to identify inequalities in weight problems between adults with ID and the general adult population, and to investigate factors associated with obesity and underweight within the ID population. Methods We undertook a population-based prevalence study of 1119 adults with ID aged 20 and over on the Leicestershire Learning Disability Register who participated in a programme of universal health checks and home interviews with their carers. We performed a cross-sectional analysis of the register data and compared the observed and expected prevalences of body mass index categories in the ID and general populations using indirect standardisation for age. We used logistic regression to evaluate the association of a range of probable demographic, physical, mental and skills attributes with obesity and underweight. Results In those aged 25 and over, the standardised morbidity ratio (SMR) for obesity was 0.80 (95% CI 0.64,1.00) in men and 1.48 (95% CI 1.23,1.77) in women. The SMR for underweight was 8.44 (95% CI 6.52,10.82) in men and 2.35 (95% CI 1.72,3.19) in women. Among those aged 20 and over, crude prevalences were 20.7% for obesity, 28.0% for overweight, 32.7% for normal weight and 18.6% for underweight. Obesity was associated with living independently/with family, ability to feed/drink unaided, being female, hypertension, Down syndrome and the absence of cerebral palsy. Underweight was associated with younger age, absence of Down syndrome and not taking medication. Conclusion Obesity in women and underweight in both men and women was more common in adults with ID than in the general population after controlling for differences in the age distributions between the two populations. The associated factors suggest opportunities for targeting high-risk groups within the ID population for lifestyle and behaviour modification. [source] Alcohol Availability and Intimate Partner Violence Among US CouplesALCOHOLISM, Issue 1 2009Christy M. McKinney Objectives:, We examined the relation between alcohol outlet density (the number of alcohol outlets per capita by zip code) and male-to-female partner violence (MFPV) or female-to-male partner violence (FMPV). We also investigated whether binge drinking or the presence of alcohol-related problems altered the relationship between alcohol outlet density and MFPV or FMPV. Methods:, We linked individual and couple sociodemographic and behavioral data from a 1995 national population-based sample of 1,597 couples to alcohol outlet data and 1990 US Census sociodemographic information. We used logistic regression for survey data to estimate unadjusted and adjusted odds ratios between alcohol outlet density and MFPV or FMPV along with 95% confidence intervals (CIs) and p -values. We used a design-based Wald test to derive a p -value for multiplicative interaction to assess the role of binge drinking and alcohol-related problems. Results:, In adjusted analysis, an increase of one alcohol outlet per 10,000 persons was associated with a 1.03-fold increased risk of MFPV (p -value for linear trend = 0.01) and a 1.011-fold increased risk of FMPV (p -value for linear trend = 0.48). An increase of 10 alcohol outlets per 10,000 persons was associated with 34% and 12% increased risk of MFPV and FMPV respectively, though the CI for the association with FMPV was compatible with no increased risk. The relationship between alcohol outlet density and MFPV was stronger among couples reporting alcohol-related problems than those reporting no problems (p -value for multiplicative interaction = 0.01). Conclusions:, We found that as alcohol outlet density increases so does the risk of MFPV and that this relationship may differ for couples who do and do not report alcohol-related problems. Given that MFPV accounts for the majority of injuries related to intimate partner violence, policy makers may wish to carefully consider the potential benefit of limiting alcohol outlet density to reduce MFPV and its adverse consequences. [source] Injury Risk Among Medically Identified Alcohol and Drug AbusersALCOHOLISM, Issue 1 2001Ted R. Miller Background: Although nonfatal injury prevalence is higher among substance abusers than in the general population, few studies have estimated the injury risk for clinically recognized substance abusers. The extant studies, moreover, analyze rates of visits for injury treatment rather than rates of injury events. This study estimates the excess risk of medically treated and hospitalized nonoccupational injury for people under age 65 with medically identified substance abuse problems and private health care coverage. Method: We conducted a retrospective cohort study by using medical claims data from Medstat Systems, Inc., with a longitudinal database of health care claims for 1.5 million people with health care coverage from 70 large corporations. Claims histories for anyone who had an alcohol-related or drug-related primary or secondary diagnosis during 1987 to 1989 were analyzed. A random sample was selected from the remaining people without a substance abuse diagnosis in their medical records. Injury rates were compared among groups. We used logistic regression to estimate odds of medically treated and hospitalized injury, controlling for demographics. Results: Medically identified substance abusers had an elevated risk of injury in a 3-year period; alcohol and drug abusers had the highest risk (58%), followed by drug-only abusers (49%), alcohol-only abusers (46%), and controls (38%). Alcohol and drug abusers were almost four times as likely to be hospitalized for an injury in a 3-year period when compared with controls. Injury risks were elevated substantially more for female then male substance abusers. Conclusions: This study greatly improves on available information about the risk of injury for drug and multiple-substance abusers. Medically identified substance abusers, especially adult women, have a higher probability of injury, more hospitalized injuries, and more injury episodes per person injured than nonabusers. More aggressive identification and subsequent treatment of female substance abusers appear warranted. [source] Self-reported antenatal adherence to medical treatment among pregnant women with Crohn's diseaseALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2010M. J. Nielsen Aliment Pharmacol Ther 2010; 32: 49,58 Summary Background, Adherence to medical treatment among women with Crohn's disease (CD) prior to and during pregnancy has never been reported. Aim, To examine both the predictors and prevalence rates of non-adherence to maintenance medical treatment among women with CD prior to and during pregnancy Methods, Among a population of 1.6 million inhabitants, we identified a total of 132 women with CD who had given birth during 2000,2005. Questionnaires were used to investigate predictors and extent of adherence. The validity of self-reported use of medication was assessed using data from the Danish Prescription Database. We used logistic regression to estimate prevalence odds ratios for non-adherence according to smoking status and other predictors. Results, Eighty percent of the patients returned the questionnaire. A total of 58 (54%) women reported to have been on medical treatment, 50 of whom had fulfilled a prescription on relevant medication. Adherence to medical treatment was 72%. Fear of a negative effect on fertility/foetus was a reason for non-adherence by 18.8% prior to, and by 45.5% during, pregnancy. Among smokers, 30.8% were non-adherent compared with 11.5% among nonsmokers (prevalence odds ratio 3.41, 95% CI 0.8,14.7). Conclusions, Despite fear of a negative effect on fertility/foetus, adherence to medical treatment is high in women with CD. There is no substantial variation in adherence prior to and during pregnancy. Smoking prior to pregnancy is a predictor of non-adherence. [source] Post-fire tree establishment patterns at the alpine treeline ecotone: Mount Rainier National Park, Washington, USAJOURNAL OF VEGETATION SCIENCE, Issue 1 2009Kirk M. Stueve Abstract Questions: Does tree establishment: (1) occur at a treeline depressed by fire, (2) cause the forest line to ascend upslope, and/or (3) alter landscape heterogeneity? (4) What abiotic and biotic local site conditions are most important in structuring establishment patterns? (5) Does the abiotic setting become more important with increasing upslope distance from the forest line? Location: Western slopes of Mount Rainier, USA. Methods: We performed classification analysis of 1970 satellite imagery and 2003 aerial photography to delineate establishment. Local site conditions were calculated from a LIDAR-based DEM, ancillary climate data, and 1970 tree locations in a GIS. We used logistic regression on a spatially weighted landscape matrix to rank variables. Results: Considerable establishment after 1970 caused forest line elevation to increase over 150 m in specific locations. Landscape heterogeneity increased with distance from the 1970 forest line. At a broad spatial context, we found establishment was most common near existing trees (0-50 m) and at low elevations (1250-1350 m). Slope aspect (W, NW, N, NE, and E), slope angle (40-60°), and other abiotic factors emerged as important predictors of establishment with increasing upslope distance from the forest line to restricted spatial extents. Conclusions: Favorable climatic conditions likely triggered widespread tree establishment. Readily available seed probably enhanced establishment rates near sexually mature trees, particularly in the less stressful environment at low elevations. The mass effect of nearly ubiquitous establishment in these areas may have obscured the importance of the abiotic setting to restricted spatial extents. Topographic variability apparently produced favorable sites that facilitated opportunistic establishment with increasing upslope distance from the forest line, thereby enabling additional trees to invade the alpine tundra. [source] Have studies of urinary tract infection and preterm delivery used the most appropriate methods?PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 3 2003Marie S. O'Neill Summary Published investigations of the association between urinary tract infection (UTI) and preterm delivery used logistic regression or chi-squared tests. Because both exposure and outcome are time dependent, these methods were not optimal and did not account for person,time under observation, potentially an important feature given the variability of women's entry to prenatal care as well as of gestational lengths. Previous researchers probably classified as exposed some women whose UTI occurred after their pregnancies exceeded 37 weeks. We applied the previous analytical methods to 1990,93 births from two Durham, NC, USA, hospitals (n = 4053) and demonstrate survival methods as an alternative. Two logistic regression models were fitted with differing exposure definitions: model 1 in which exposed = UTI diagnosed after 20 weeks' gestation; and model 2 in which exposed = UTI diagnosed between 20 weeks' and 37 weeks' gestation. Model 3 used proportional hazards regression with person,time after 20 weeks and before UTI diagnosis as unexposed, and person,time after diagnosis as exposed. Models were fit with and without five time-constant potential confounders. Model 1 yielded an adjusted odds ratio (OR) of 0.8 [95% confidence interval (CI) 0.5, 1.2], and model 2, which did not include UTI diagnoses after 37 weeks, an adjusted OR of 0.9 [95% CI 0.6, 1.4]. The Cox model hazard ratio (HR) for preterm delivery was 1.1 (adjusted) [95% CI 0.7, 1.7]. As these results indicated some bias, but not remarkable differences, we conducted a sensitivity analysis using 100 samples of 80% of the original data set, with replacement to determine how large the differences might be in other, similar data sets. The Cox method consistently produced higher effect estimates than either logistic model. The two samples with the greatest differences between the Cox and logistic model estimates yielded an OR of 1.47 [95% CI 0.95, 2.29] for model 1 vs. HR of 2.06 [95% CI 1.39, 3.06] for model 3, and an OR of 1.41 [95% CI 0.88, 2.25] for model 2 vs. HR of 1.79 [95% CI 1.17, 2.71] for model 3 respectively. Previous published results on UTI and preterm delivery require cautious interpretation. Data on UTI timing should be gathered to allow appropriate analyses; survival methods account for person,time under observation and ensure that studied exposures precede effects. [source] Evaluating uses of data mining techniques in propensity score estimation: a simulation study,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 6 2008DrPH, Soko Setoguchi MD Abstract Background In propensity score modeling, it is a standard practice to optimize the prediction of exposure status based on the covariate information. In a simulation study, we examined in what situations analyses based on various types of exposure propensity score (EPS) models using data mining techniques such as recursive partitioning (RP) and neural networks (NN) produce unbiased and/or efficient results. Method We simulated data for a hypothetical cohort study (n,=,2000) with a binary exposure/outcome and 10 binary/continuous covariates with seven scenarios differing by non-linear and/or non-additive associations between exposure and covariates. EPS models used logistic regression (LR) (all possible main effects), RP1 (without pruning), RP2 (with pruning), and NN. We calculated c-statistics (C), standard errors (SE), and bias of exposure-effect estimates from outcome models for the PS-matched dataset. Results Data mining techniques yielded higher C than LR (mean: NN, 0.86; RPI, 0.79; RP2, 0.72; and LR, 0.76). SE tended to be greater in models with higher C. Overall bias was small for each strategy, although NN estimates tended to be the least biased. C was not correlated with the magnitude of bias (correlation coefficient [COR],=,,0.3, p,=,0.1) but increased SE (COR,=,0.7, p,<,0.001). Conclusions Effect estimates from EPS models by simple LR were generally robust. NN models generally provided the least numerically biased estimates. C was not associated with the magnitude of bias but was with the increased SE. Copyright © 2008 John Wiley & Sons, Ltd. [source] Recommendations for the Assessment and Reporting of Multivariable Logistic Regression in Transplantation LiteratureAMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2010A. C. Kalil Multivariable logistic regression is an important method to evaluate risk factors and prognosis in solid organ transplant literature. We aimed to assess the quality of this method in six major transplantation journals. Eleven analytical criteria and four documentation criteria were analyzed for each selected article that used logistic regression. A total of 106 studies (6%) out of 1,701 original articles used logistic regression analyses from January 1, 2005 to January 1, 2006. The analytical criteria and their respective reporting percentage among the six journals were: Linearity (25%); Beta coefficient (48%); Interaction tests (19%); Main estimates (98%); Ovefitting prevention (84%); Goodness-of-fit (3.8%); Multicolinearity (4.7%); Internal validation (3.8%); External validation (8.5%). The documentation criteria were reported as follows: Selection of independent variables (73%); Coding of variables (9%); Fitting procedures (49%); Statistical program (65%). No significant differences were found among different journals or between general versus subspecialty journals with respect to reporting quality. We found that the report of logistic regression is unsatisfactory in transplantation journals. Because our findings may have major consequences for the care of transplant patients and for the design of transplant clinical trials, we recommend a practical solution for the use and reporting of logistic regression in transplantation journals. [source] Neurologic signs and symptoms in fibromyalgiaARTHRITIS & RHEUMATISM, Issue 9 2009Nathaniel F. Watson Objective To determine the type and frequency of neurologic signs and symptoms in individuals with fibromyalgia (FM). Methods Persons with FM (n = 166) and pain-free controls (n = 66) underwent systematic neurologic examination by a neurologist blinded to disease status. Neurologic symptoms lasting at least 3 months were assessed with a standard questionnaire. We used logistic regression to evaluate the association of neurologic symptoms and examination findings with FM status. Within the FM group we examined the correlation between self-reported symptoms and physical examination findings. Results Age- and sex-adjusted estimates revealed that compared with the control group, the FM group had significantly more neurologic abnormalities in multiple categories, including greater dysfunction in cranial nerves IX and X (42% versus 8%) and more sensory (65% versus 25%), motor (33% versus 3%), and gait (28% versus 7%) abnormalities. Similarly, the FM group had significantly more neurologic symptoms than the control group in 27 of 29 categories, with the greatest differences observed for photophobia (70% versus 6%), poor balance (63% versus 4%), and weakness (58% versus 2%) and tingling (54% versus 4%) in the arms or legs. Poor balance or coordination, tingling or weakness in the arms or legs, and numbness in any part of the body correlated with appropriate neurologic examination findings in the FM group. Conclusion This blinded, controlled study demonstrated neurologic physical examination findings in persons with FM. The FM group had more neurologic symptoms than did the controls, with moderate correlation between symptoms and signs. These findings have implications for the medical evaluation of patients with FM. [source] Central bone marrow lesions in symptomatic knee osteoarthritis and their relationship to anterior cruciate ligament tears and cartilage lossARTHRITIS & RHEUMATISM, Issue 1 2008Gabriela Hernández-Molina Objective Medial and lateral compartment bone marrow lesions (BMLs) have been tied to cartilage loss. We undertook this study to assess 2 types of BMLs in the central region of the knee (type 1 BMLs, which are related anatomically to anterior cruciate ligament [ACL]/posterior cruciate ligament [PCL] insertions, and type 2 BMLs, which encompass both the central region and either the medial or the lateral compartment) and determine their relationship to cartilage loss and ACL tears. Methods Magnetic resonance imaging (MRI) of the knee was performed at baseline and at followup (15 and/or 30 months) in 258 subjects with symptomatic osteoarthritis (OA). At baseline, we assessed ACL tears and central BMLs located at or between the tibial spines or adjacent to the femoral notch. Cartilage loss was present if the score in any region of the tibiofemoral joint increased by ,1 units at the last available followup, using a modified Whole-Organ MRI Score. We used logistic regression adjusted for alignment, body mass index, Kellgren/Lawrence score, sex, and age. Results One hundred thirty-nine knees (53.8%) had central BMLs, of which 129 had type 1 BMLs (96 abutted the ACL and had no coexistent type 2 features) and 25 had type 2 BMLs (often overlapped with type 1). Type 1 lesions were associated with ACL tears (odds ratio [OR] 5.9, 95% confidence interval [95% CI] 2.2,16.2) but not with cartilage loss (OR 1.6, 95% CI 0.8,3.1), while medial type 2 BMLs were related to medial cartilage loss (OR 6.1, 95% CI 1.0,35.2). Conclusion Central BMLs that abutted the ACL were highly prevalent and strongly related to ACL pathology, suggesting a role of enthesopathy in OA. Only BMLs with medial extension were related to ipsilateral cartilage loss. [source] Using the Optimal Robust Receiver Operating Characteristic (ROC) Curve for Predictive Genetic TestsBIOMETRICS, Issue 2 2010Qing Lu Summary Current ongoing genome-wide association (GWA) studies represent a powerful approach to uncover common unknown genetic variants causing common complex diseases. The discovery of these genetic variants offers an important opportunity for early disease prediction, prevention, and individualized treatment. We describe here a method of combining multiple genetic variants for early disease prediction, based on the optimality theory of the likelihood ratio (LR). Such theory simply shows that the receiver operating characteristic (ROC) curve based on the LR has maximum performance at each cutoff point and that the area under the ROC curve so obtained is highest among that of all approaches. Through simulations and a real data application, we compared it with the commonly used logistic regression and classification tree approaches. The three approaches show similar performance if we know the underlying disease model. However, for most common diseases we have little prior knowledge of the disease model and in this situation the new method has an advantage over logistic regression and classification tree approaches. We applied the new method to the type 1 diabetes GWA data from the Wellcome Trust Case Control Consortium. Based on five single nucleotide polymorphisms, the test reaches medium level classification accuracy. With more genetic findings to be discovered in the future, we believe a predictive genetic test for type 1 diabetes can be successfully constructed and eventually implemented for clinical use. [source] Mania profile in a community sample of prepubertal children in TurkeyBIPOLAR DISORDERS, Issue 4 2008Rasim Somer Diler Background:, Mania in youth is increasingly recognized and accompanied by substantial psychiatric and psychosocial morbidity. There are no data on prepubertals in the general population and we aimed to search for mania symptoms and its clinical correlations in a community sample of prepubertal Turkish children. Methods:, Among all children (n = 56,335) aged 7,11 in Adana, Turkey, 2,468 children (48% girls) were randomly included. Parents completed Child Behavior Checklist (CBCL) 4,18 and Parent-Young Mania Rating Scale (P-YMRS). Cut-off scores of 17 and 27 on total P-YMRS were defined as efficient (probable-mania group) and specific (mania group), respectively, for bipolar profile. We searched for clinical correlations and used logistic regression to show how well each CBCL subscale predicted the presence of mania and probable-mania, after adjusting for any demographic differences. Results:, Parent-Young Mania Rating Scale scores were ,17 but <27 (probable-mania) in 155 (6.3%) children and ,27 (mania) in 32 (1.3%) children. Elevated mood, increased activity levels, and poor insight were the most frequent manic symptoms in our sample. Children with probable-mania and mania had higher scores on all CBCL subscales and the CBCL-Pediatric Bipolar Disorder (CBCL-PBD) profile (sum of attention, aggression, and anxiety/depression subscales). Logistic regression analysis revealed only thought problems on CBCL that predicted probable-mania and mania. Conclusion:, Our study shows that mania profile is common in the community sample of Turkish prepubertal children and does not support the thought that mania is rare outside the US. We need further population-based studies that will use diagnostic interviews and multiple informants. [source] Association between lactate in vaginal fluid and time to spontaneous onset of labour for women with suspected prelabour rupture of the membranesBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 12 2006E Wiberg-Itzel Objectives, To assess whether lactate determination in vaginal fluid is associated with, and can predict, onset of labour for women with suspected prelabour rupture of the membranes (PROM). Design, Prospective observational study. Setting, Labour ward at Soder Hospital, Stockholm, Sweden. Population, Women with suspected PROM after 34 weeks of gestation, who later had spontaneous onset of labour (n= 179). Methods, All women underwent a speculum examination and a test for determining lactate concentration in vaginal fluid. We used logistic regression to estimate the association between lactate concentration in vaginal fluid and time to onset of labour. Main outcome measures, Time from examination to onset of labour (cervix ,4 cm), within 24 hours and 48 hours. Results, The median time interval between examination and spontaneous onset of labour was 8.4 hours for women with ,high' lactate (,4.5 mmol/l) and 54 hours for those with ,low' lactate concentrations (<4.5 mmol/l). Among 86 women with high lactate concentrations, 76 (88%) had started labour within 24 hours compared with 20 of 93 (22%) women with low lactate concentrations (OR 27.7, 95% CI 12.2,63.3). After checking for the effect of visible amniotic fluid, the corresponding odds were still substantially increased (OR 13.5, 95% CI 5.3,34.3). Conclusions, High lactate concentration (,4.5 mmol/l) in vaginal fluid can be used to predict whether a woman with suspected PROM will commence spontaneous onset of labour within 24 or 48 hours. [source] Breast-feeding and a subsequent diagnosis of measlesACTA PAEDIATRICA, Issue 4 2009SA Silfverdal Abstract Background: Breast-feeding protects against many infectious diseases and may also influence immunization outcomes. Aim: This study investigated if breast-feeding protects against clinical measles and if it modified the effect of immunization. Methods: We used logistic regression with data for 10 207 individuals from the 1970 British Cohort study (BCS70). Breast-feeding data were collected at five years of age, and information on clinical measles infection, as well as socio-economic measures was collected at the age of ten years. Breast feeding was categorized as: breast-fed <1 month (n = 1611), breast-fed for 1,3 months (n = 1016), breast-fed for more than three months (n = 1108), breast-feeding of uncertain duration (n = 21) and never breast-fed (n = 6451). Results: Breast-feeding for more than three months was negatively associated with a diagnosis of clinical measles infection after adjustment for crowding, social class, measles vaccination, parity and sex with an odds ratio (95% confidence interval) of 0.69 (0.60,0.81) compared with those who never breast-fed. Measles vaccination was highly associated with low risk for measles with: 0.14 (0.13,0.16). Age at acute measles infection was not associated with breastfeeding. Breast-feeding did not notably alter measles immunization efficacy. Conclusion: Immunization against measles provides effective protection against the disease. A more modest reduction in the risk of a measles diagnosis is associated with breast-feeding. The associations with a diagnosis of measles for breast-feeding and measles immunization are independent of each other. [source] Cost-effectiveness analysis of triple test in second-trimester maternal serum screening for Down's syndrome: an experience from Taiwan with decreasing birth rate but increasing population of old pregnant womenJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 2 2008Hsiao-Lin Hwa PhD Objectives, We intended to assess the cost-effectiveness of adding unconjugated oestriol (uE3) in maternal serum screening for Down's syndrome in Taiwan, where there is a decreasing birth rate but an increasing trend of old women having pregnancies. Methods, We used logistic regressions to estimate the risk of Down's syndrome with maternal age and different combinations of biomarkers. Cost-effectiveness analysis was presented in terms of the average and incremental cost-effectiveness ratios. Sensitivity analyses with different parameters were performed. Results, Given a cut-off point of 1:270 for the confirmation of Down's syndrome with amniocentesis, the average cost per case averted for maternal age above 35 years only, double test [alpha-fetoprotein (AFP) and human chorionic gonadotrophin (hCG)] and triple test (AFP, hCG and uE3) were estimated as $14 561, $42 367 and $37 424. The additional costs per case averted for double test and triple test (compared with maternal age above 35 years) were $135 950 and $77 394, respectively. The additional cost per case averted for triple test was $15 199 compared with double test. Conclusions, The performance of triple test is not only more effective in detecting Down's syndrome cases but also more cost-effective than double test in this study. [source] | ||||||||||||||||