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Cross-sectional Population (cross-sectional + population)
Selected AbstractsRisk Factors for Fear of Falling: A Cross-Sectional Population-Based StudyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2009Arnaud Rossat BS (Econ) No abstract is available for this article. [source] Prevalence of the metabolic syndrome in the island of Gran Canaria: comparison of three major diagnostic proposalsDIABETIC MEDICINE, Issue 12 2005M. Boronat Abstract Aims The present study was conducted to estimate the prevalence of the metabolic syndrome in a Canarian population, and to compare its frequency as defined by the most commonly used working definitions. Methods Cross-sectional population-based study. One thousand and thirty adult subjects were randomly selected from the local census of Telde, a city located on the island of Gran Canaria. Participants completed a survey questionnaire and underwent physical examination, fasting blood analyses, and a 75-g standardized oral glucose tolerance test. The prevalence of the metabolic syndrome was estimated according to the definitions proposed by the World Health Organization (WHO), the European Group for the Study of Insulin Resistance (EGIR) and the National Cholesterol Education Program (NCEP), the latter with the original (6.1 mmol/l) and the revised criterion (5.6 mmol/l) for abnormal fasting glucose. Results The adjusted prevalence of the metabolic syndrome was 28.0, 15.9, 23.0 and 28.2%, using the WHO, EGIR, NCEP and revised NCEP criteria, respectively. The measure of agreement (, statistic) was 0.57 between the WHO and the original NCEP definitions, and 0.61 between the WHO and the revised NCEP definitions. After excluding diabetic subjects, the agreement between the EGIR and WHO proposals was fairly good (, = 0.70), whereas concordance of the EGIR with the original and the revised NCEP definitions was moderate (, = 0.47 and 0.46, respectively). Conclusions Whichever the considered diagnostic criteria, the prevalence of the metabolic syndrome in this area of the Canary Islands is greater than that observed in most other European populations. [source] Probabilities of alcohol high-risk drinking, abuse or dependence estimated on grounds of tobacco smoking and nicotine dependenceADDICTION, Issue 6 2003Ulrich John ABSTRACT Aims, To estimate probabilities of alcohol high-risk drinking, alcohol abuse and alcohol dependence on grounds of smoking-behaviour related variables and single nicotine dependence criteria. Design, Cross-sectional population-based study. Setting, Adult population of a region in north Germany. Participants, Cigarette smokers (n = 2437) among a random sample of 4075 females and males aged 18,64, drawn in 1996. Measurement, Smoking, nicotine dependence according to the Diagnostic and Statistical Manual of Psychiatric Disorders (DSM-IV) and the Fagerström Test for Nicotine Dependence (FTND); increasing alcohol-related harm (ARH): high-risk drinking, DSM-IV alcohol abuse, remitted and current alcohol dependence diagnosed by the Composite International Diagnostic Interview (CIDI). Findings, Having smoked 30 cigarettes or more per day, onset of smoking at the age of 17 or younger, nicotine dependence and single nicotine dependence criteria revealed odds ratios higher than 4.0 for alcohol dependence. For alcohol dependence, a logistic regression model showed an increased odds ratios for male gender, smoking for 25 years or more, no attempt to quit or cut down, continuation of smoking despite problems, craving for nicotine, withdrawal experience 1 day or longer, smoking first cigarette in the morning 5 minutes or less after waking. The probability of increasing ARH was more likely in males, smokers for 25 years or more, no attempt to quit or cut down, continuation of smoking despite problems and smoking first cigarette in the morning 5 minutes or less after waking. Conclusions, Gender and single nicotine dependence criteria show particularly high probabilities of alcohol dependence and increasing ARH. Interventions need to take these connections into account. [source] Impaired Fasting Glucose Is Associated with Increased Arterial Stiffness in Elderly People without Diabetes Mellitus: The Rotterdam StudyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2006Nicole M. Van Popele MD OBJECTIVES: To study the association between impaired fasting glucose (IFG) and arterial stiffness in older adults. DESIGN: Cross-sectional population-based study. SETTING: The Rotterdam Study, a Dutch population-based cohort study. PARTICIPANTS: Two thousand nine hundred eighty-seven subjects aged 60 and older. MEASUREMENTS: Arterial stiffness assessed by measuring common carotid arterial distensibility and glucose status classified into three categories: normal fasting glucose (NFG) (fasting glucose <6.1 mmol/L), IFG (fasting glucose 6.1,6.9 mmol/L), and diabetes mellitus (DM). RESULTS: In the total cohort, common carotid distensibility decreased with increasing impairment of glucose metabolism. Subjects younger than 75 with IFG were comparable with subjects with NFG with respect to arterial stiffness. Subjects aged 75 and older with IFG had stiffer arteries than subjects with NFG, reaching the same arterial stiffness as subjects with DM. For subjects younger than 75, mean difference in distensibility coefficient between subjects with NFG and with IFG was 0.1 (95% confidence interval (CI)=,0.04,0.05, P=.88) and between subjects with NFG and with DM was 1.2 (95% CI=0.7,1.7, P<.001). For subjects aged 75 and older, the mean difference between these groups was 0.7 (95% CI=0.2,1.2, P=.007) and 0.8 (0.3,1.4; P=.002), respectively. In the total cohort, fasting glucose was strongly associated with carotid distensibility (,-coefficient=,0.29, P<.001). CONCLUSION: IFG is related to arterial stiffness in elderly subjects. An advanced stage of arterial stiffness, comparable with that of subjects with DM, is only reached at the age of 75. [source] Glycated Hemoglobin Levels and Intellectual Activity in an Aged PopulationJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 12 2005Hidenori Amano MHSc Objectives: To examine the association between glycated hemoglobin (GHb) and aspects of daily activities in an elderly population. Design: Cross-sectional population-based survey. Setting: Nangai village, an agricultural community with a population of about 5,000 located in Akita prefecture in the north of Japan. Participants: Nine hundred thirty-five people aged 65 and older. Measurements: GHb percentages, self-reported measures of activities of daily living (ADLs) and instrumental activities of daily living (IADLs), intellectual activity (IA), and social role (SR). Results: An exploratory analysis indicated that nondiabetic subjects in the lowest tertile of GHb tend to have lower IA than those in the middle tertile, if they were aged 70 and older. No consistent association appeared between GHb and ADLs, IADLs, or SR. Linear and logistic regression analyses, controlling for other risk factors, indicated significantly lower IA scores in the low and high GHb tertiles (P<.001 and P=.04, respectively) than in the middle in nondiabetic subjects aged 70 and older and without stroke history or IADL impairments. The value of GHb related to the maximal IA score was 5.0% to 5.2% as the middle tertile; or 5.2%, assuming a logistic regression model including a squared term with GHb as a continuous variable. A similar relationship was observed in the whole nondiabetic sample aged 70 and older but not in the younger counterpart. Conclusion: There is an inverted U-shaped relationship between GHb and intellectual activity in older people without diabetes mellitus. One possible interpretation is that suboptimal blood glucose could contribute to intellectual inactivity in older people. [source] Adipocytokines and the metabolic syndrome among older persons with and without obesity: the InCHIANTI studyCLINICAL ENDOCRINOLOGY, Issue 1 2010Sari Stenholm Summary Objectives, Adipose tissue-derived inflammation may contribute to metabolic alterations and eventually to the metabolic syndrome (MetS). The purpose of this study was to: (1) examine the role of adipocytokines in the association between obesity and the MetS and (2) to determine whether the association is different in obese and non-obese persons. Design, Cross-sectional population-based InCHIANTI study. Subjects, A total of 944 community-dwelling adults aged 65 years and older living in Tuscany, Italy. Measurements, Obesity was defined as body mass index ,30 kg/m2 and MetS as ,3 of the ATP-III criteria. Circulating levels of C-reactive protein, interleukin (IL)-6, IL-1 receptor antagonist (IL-1ra), IL-18, tumour necrosis factor (TNF)-, R1, adiponectin, resistin and leptin were measured. Additionally, insulin resistance was determined using the homeostasis model assessment (HOMA-IR). Results, The prevalence of the MetS was 32%. Both overall and abdominal obesity were significantly associated with the MetS after adjusting for inflammatory cytokines, adipokines and lifestyle factors. After adjusting for multiple confounders and HOMA-IR, IL-1ra, TNF-, R1 and adiponectin (P < 0·05) remained significantly associated with the MetS. Having multiple cytokines in the highest tertile increased the likelihood of having the MetS in both obese (P for trend 0·002) and non-obese persons (P for trend 0·001) independent of insulin resistance. Conclusions, Non-obese and obese individuals who develop an intense pro-inflammatory state may be more prone to develop the MetS than those with lower levels of inflammation. [source] The relationship between depression and diabetes mellitus: findings from the Hertfordshire Cohort StudyDIABETIC MEDICINE, Issue 6 2009R. I. G. Holt Abstract Aims, To assess the relationship between depression scores and diabetes, glucose and insulin in a cross-sectional population-based study. Methods, One thousand, five hundred and seventy-nine men and 1418 women from the Hertfordshire Cohort Study were assessed for diabetes. Plasma glucose and insulin concentrations were measured at 0, 30 and 120 min during a standard 75-g oral glucose tolerance test. Depressive and anxiety symptoms were measured using the Hospital Anxiety and Depression Scale (HADS). Results, Overall, 431 (14.6%) were diagnosed with diabetes [232 men (14.9%) and 199 women (14.3%)]. One hundred and eight (47%) men and 74 (37%) women had known diabetes. The remainder were previously undiagnosed. Fifty-nine (3.7%) men and 65 (4.6%) women had possible depression (HAD-D scores 8,10) and 17 (1.1%) men and 20 (1.4%) women had probable depression (HAD-D scores , 11). Probable depression was associated with an adjusted odds ratio for diabetes of 3.89 [95% confidence interval (CI) 1.28,11.88] in men and 1.51 (95% CI 0.47,4.84) in women. In men without previously diagnosed diabetes, fasting insulin (P = 0.035), 2-h glucose concentrations (P = 0.028) and insulin resistance (P = 0.032) were significantly associated with HAD-D scores. With the exception of 2-h glucose concentrations (P = 0.034), the associations were not significant in women. Conclusions, These data support the hypothesis that depression may increase the risk for diabetes. The relationship between depression score and metabolic variables extends across the whole population and is not confined to those with either diagnosed depression or diabetes. This relationship should lead clinicians to consider screening for diabetes in those with depression and vice versa. [source] The metabolic syndrome and changing relationship between blood pressure and insulin with age, as observed in Aboriginal and Torres Strait Islander peoplesDIABETIC MEDICINE, Issue 11 2005A. E. Schutte Abstract Aims To determine the prevalence of the metabolic syndrome (MS) among Aboriginal and Torres Strait Islander peoples. A further objective was to investigate the relationships between fasting insulin and blood pressure (BP) within these groups with increasing age. Methods A cross-sectional population-based study included 369 Torres Strait Islanders (residing in Torres Strait and Far North Queensland), and 675 Aborigines from central Australia. Data necessary for classification of MS was collected, including fasting and 2-h glucose and insulin, urinary albumin and creatinine, anthropometric measurements, BP, serum lipids. Results The ATPIII criteria classified 43% of Torres Strait Islanders and 44% of Aborigines with MS, whereas 32 and 28%, respectively, had the MS according to WHO criteria. Agreement between the two criteria was only modest (kappa coefficient from 0.28 to 0.57). Factor analyses indicated no cluster including both insulin and BP in either population. Significant correlations (P < 0.05) [adjusted for gender, body mass index (BMI) and waist circumference] were observed between BP and fasting insulin: a positive correlation for Torres Strait Islanders aged 15,29 years, and an inverse correlation for Aborigines aged 40 years and older. Conclusion Torres Strait Islanders and Aborigines had very high prevalences of the MS. Specific population characteristics (high prevalences of central obesity, dyslipidaemia, renal disease) may make the WHO definition preferable to the ATPIII definition in these population groups. The poor agreement between criteria suggests a more precise definition of the metabolic syndrome that is applicable across populations is required. This study showed an inverse relationship with age for the correlation of BP and fasting insulin. [source] First positive reactions to cannabis constitute a priority risk factor for cannabis dependenceADDICTION, Issue 10 2009Yann Le Strat ABSTRACT Aim To assess the association between first reactions to cannabis and the risk of cannabis dependence. Design A cross-sectional population-based assessment in 2007. Setting A campus in a French region (Champagne-Ardennes). Participants A total of 1472 participants aged 18,21 years who reported at least one life-time cannabis consumption, of 3056 students who were screened initially [the Susceptibility Addiction Gene Environment (SAGE) study]. Measurements Positive and negative effects of first cannabis consumptions, present cannabis dependence and related risk factors were assessed through questionnaires. Findings The effects of first cannabis consumptions were associated dose-dependently with cannabis dependence at age 18,21 years, both according to the transversal approach of the SAGE study and to the prospective cohort of the Christchurch Health and Development Study (CHDS) assessed at the age of 25 years. Participants of the SAGE study who reported five positive effects of their first cannabis consumption had odds of life-time cannabis dependence that were 28.7 (95% confidence interval: 14.6,56.5) higher than those who reported no positive effects. This association remains significant after controlling for potentially confounding factors, including individual and familial variables. Conclusions This study suggests an association between positive reactions to first cannabis uses and risk of life-time cannabis dependence, this variable having a central role among, and through, other risk factors. [source] Anxiety and depression among abstainers and low-level alcohol consumers.ADDICTION, Issue 9 2009The Nord-Trøndelag Health Study ABSTRACT Aims The aim of this study was to examine the levels of anxiety and depression among individuals consuming low levels of alcohol. Design Prospective and cross-sectional population-based study. Setting and participants This study employed data from the Nord-Trøndelag Health Survey (HUNT-2, n = 38 930). Measurements Alcohol consumption was measured by self-report of usual alcohol consumption during a 2-week period. Low-level alcohol consumption was defined as self-reported abstainers and non-abstainers currently consuming no alcohol. Anxiety and depression were measured using the Hospital Anxiety and Depression Rating Scale. Potential explanatory variables included somatic illness and symptoms, health-related behaviour, socio-economic status and social activity. In a subsample (n = 20 337), we also looked at the impact of previous heavy drinking among abstainers ('sick-quitting'). Findings A U-shaped association between alcohol consumption and the risk of anxiety and depression was found. Abstention was related to increased odds for both case-level anxiety [1.34, 95% confidence interval (CI) 1.19,1.52] and depression (1.52, 95% CI 1.30,1.77). This association was accounted for partly by adjustments for socio-economic status, social network, somatic illness, age (depression only), gender (anxiety only) and ,sick-quitting'. We also identified significant differences between participants who label themselves as abstainers compared to those who report no usual alcohol consumption, but who do not label themselves as abstainers. Conclusions The risk of case-level anxiety and depression is elevated in individuals with low alcohol consumption compared to those with moderate consumption. Individuals who label themselves as abstainers are at particularly increased risk. This increased risk cannot fully be explained by somatic illness, social activity or ,sick-quitting'. [source] The co-occurrence of headache and musculoskeletal symptoms amongst 51 050 adults in NorwayEUROPEAN JOURNAL OF NEUROLOGY, Issue 5 2002K. Hagen We have evaluated the association between headache and musculoskeletal symptoms in a large cross-sectional population-based study. Between 1995 and 1997, all 92 566 adults in Nord-Trøndelag County in Norway were invited to participate in a health survey. A total of 51 050 (55%) responded to questions concerning headache and musculoskeletal symptoms. Both migraine and non-migrainous headache were strongly associated with musculoskeletal symptoms. However, frequency of headache had a higher impact than headache diagnosis on this association. Thus, the prevalence of chronic headache (headache >14 days/month) was more than four times higher (OR = 4.6; 95% CI 4.0,5.3) in the group of individuals with musculoskeletal symptoms than in those without. Individuals with neck pain were more likely to suffer from headache as compared with those with musculoskeletal symptoms in other restricted areas. In conclusion, there was a strong association between chronic headache and musculoskeletal symptoms, which may have implications for the choice of treatment. [source] Is Headache Related to Asthma, Hay Fever, and Chronic Bronchitis?HEADACHE, Issue 2 2007The Head-HUNT Study Objectives.,To examine the relationship between migraine and nonmigrainous headache and asthma, hay fever, and chronic bronchitis in a large cross-sectional population-based study. Background.,Associations between prevalence of migraine and asthma or allergy have been demonstrated in clinic-based and epidemiologic studies whereas studies on chronic bronchitis are scarce. Methods.,A total of 51,383 subjects completed a headache questionnaire and constituted the "Head-HUNT" Study. Of these 50,401 (98.1%) answered the questions about asthma and chronic bronchitis, and 47,029 (91.5%) answered the question about hay fever. Associations were assessed in multivariate analyses, estimating prevalence odds ratios (ORs) with 95% confidence intervals (CI). Results.,Both migraine and nonmigrainous headache were approximately 1.5 times more likely among those with current asthma, asthma related symptoms, hay fever, and chronic bronchitis than those without. The association increased with increasing headache frequency. Conclusions.,This large questionnaire-based study confirms that migraine and other headaches are associated with respiratory and allergic disorders. The magnitude of the association between headache and asthma, hay fever, and chronic bronchitis tended to be in the same order. Headache frequency seems to have a greater impact on the association with respiratory or allergic conditions than headache diagnoses. Whether it is a causal relationship is uncertain, but the results underline the importance of considering comorbid disorders among patients with frequent headache. [source] Endogenous testosterone levels and smoking in men.INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 3 2007The fifth Tromsø study Summary Smoking is a risk factor of coronary heart disease (CHD), while the role of testosterone in the development of CHD is controversial. The reported effects of cigarette smoking on testosterone levels in men are conflicting, and smoking may be an important confounding factor when evaluating the relationship between testosterone levels and CHD. Thus, the objective of the present study was to examine the associations of smoking status and number of cigarettes smoked per day with total and free testosterone levels in a cross-sectional population-based study of 3427 men participating in the fifth Tromsø study. Total testosterone, luteinizing hormone, follicle-stimulating hormone and sex hormone-binding globulin levels were measured with immunoassay while free testosterone levels were calculated. Waist circumference was also measured and two standardized questionnaires were completed, including smoking status and number of cigarettes smoked. The data were analysed with analysis of variance and covariance and multiple regression analysis. Smoking men had significantly higher levels of total and free testosterone compared with men who never smoked (p < 0.001 and <0.01 respectively). Both total and free testosterone levels increased significantly with increasing number of cigarettes smoked daily (p < 0.001). Smoking men had 15% higher total and 13% higher free testosterone levels compared with men who never smoked. Thus, smoking seems to be an important confounding factor when evaluating testosterone levels, and could possibly mask borderline hypogonadism. [source] The association between physical activity and hot flash severity, frequency, and duration in mid-life womenAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2009William A. Romani The value of physical activity to reduce vasomotor symptoms has yet to be determined conclusively. As a result, we used a cross-sectional population-based design to examine the association between self reported physical activity level and hot flash symptoms in 45,54-year-old women. Participants (n = 603) completed a detailed survey to report physical activity level at work, home, and leisure as well as a detailed history of the frequency and severity of hot flash symptoms. Results showed that higher levels of physical activity were significantly associated with increasing odds of moderate or severe hot flashes (P for trend = 0.02). These findings suggest that there is a positive relation between physical activity and moderate or severe hot flash symptoms but no relation between physical activity and the reporting of any hot flashes, daily hot flashes, or hot flashes experienced for greater than 1 year. Am. J. Hum. Biol., 2009. © 2008 Wiley-Liss, Inc. [source] Socioeconomic and lifestyle determinants of body fat distribution in young working males from Cracow, PolandAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2008Agnieszka Suder The aim of the study was to determine the degree of explanation of the central adiposity variation, presented by waist circumference (WC), waist-hip ratio (WHR), and the sum of the three trunk skinfold thicknesses (subscapular, abdominal, suprailiac) (TTS) through the socioeconomic status (SES) and lifestyle. The material included cross-sectional population-based research of 259 healthy working males aged 20,30 from the city of Cracow, Poland. Objective anthropometric measurements, the results of motor fitness tests, and social and lifestyle data from a questionnaire were analyzed. The independent variables were: age, SES (the birthplace, place of residence until the age of 14, social class, educational level, and the type of work done), and lifestyle elements (smoking habits, dietary habits, family obesity resemblance, sport activity in the past, leisure time physical activity (LTPA), and the level of motor fitness). Three separate full models were created using stepwise straightforward regression with WC, WHR, and TTS as dependent variables. The highest autonomous influence on WC was ascribed to age, level of motor fitness, and family obesity resemblance. Variation in WHR was explained by age, level of motor fitness, upper-middle class, LTPA, and village as the birthplace. Level of motor fitness, place of residence until the age of 14 (city), age, smoking fewer than 20 cigarettes a day, and family obesity resemblance had greatest influence on TTS. The findings indicated the importance, besides age, of lifestyle elements connected with motor fitness and LTPA in determining body fat distribution in young working males. Am. J. Hum. Biol., 2008. © 2007 Wiley-Liss, Inc. [source] Association of interleukin-6 and interleukin-10 genotypes with radiographic damage in rheumatoid arthritis is dependent on autoantibody statusARTHRITIS & RHEUMATISM, Issue 8 2007I. Marinou Objective Recent evidence has highlighted a major genetic contribution to radiographic damage in rheumatoid arthritis (RA). The objective of this study was to determine whether genetic variants in the loci for interleukin-1 (IL-1), IL-6, IL-10, protein tyrosine phosphatase N22 (PTPN22), and selenoprotein S are associated with radiographic damage. Methods Modified Larsen scores of radiographic damage were determined in a cross-sectional population of patients with RA (n = 964). Rheumatoid factor (RF) and anti,cyclic citrullinated peptide (anti-CCP) were also assayed. The Kruskal-Wallis nonparametric test was used to compare median radiographic damage scores across genotype groups, followed by the Cuzick nonparametric test for trend to assess gene-dose effects. Results An allele-dose association of IL-6 ,174G with increasing radiographic damage was present (P = 0.005), but only in patients who were RF positive (P = 0.004) or anti-CCP positive (P = 0.01). Patients with the IL-10 ,592CC genotype had more extensive radiographic damage than did those with the AC or AA genotype (P = 0.006), but this was observed only among patients who were RF negative (P = 0.002) or anti-CCP negative (P = 0.002). However, RF status and anti-CCP status were not associated with the IL-6 or IL-10 genotype. No other genetic associations were detected, apart from a marginal association of PTPN22 +1858T with increased radiographic damage. Conclusion The reported associations of IL-6 ,174G with high IL-6 production and IL-10 ,592 with low IL-10 production and our own results support a role of genetically determined dysregulated cytokine production in disease severity. The lack of association of these genotypes with RF and anti-CCP antibody status suggests that they act downstream of autoantibody production. We conclude that IL-6 and IL-10 genotypes may be useful in predicting disease severity in autoantibody-positive and autoantibody-negative patients, respectively. [source] Unwanted sexual advances at work: variations by employment arrangement in a sample of working AustraliansAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 2 2009Anthony D. LaMontagne Abstract Objective: We tested the hypothesis that the risk of experiencing unwanted sexual advances at work (UWSA) is greater for precariously-employed workers in comparison to those in permanent or continuing employment. Methods: A cross-sectional population-based telephone survey was conducted in Victoria (66% response rate, N=1,101). Employment arrangements were analysed using eight differentiated categories, as well as a four-category collapsed measure to address small cell sizes. Self-report of unwanted sexual advances at work was modelled using multiple logistic regression in relation to employment arrangement, controlling for gender, age, and occupational skill level. Results: Forty-seven respondents reported UWSA in our sample (4.3%), mainly among women (37 of 47). Risk of UWSA was higher for younger respondents, but did not vary significantly by occupational skill level or education. In comparison to Permanent Full-Time, three employment arrangements were strongly associated with UWSA after adjustment for age, gender, and occupational skill level: Casual Full-Time OR = 7.2 (95% Confidence Interval 1.7-30.2); Fixed-Term Contract OR = 11.4 (95% CI 3.4-38.8); and Own-Account Self-Employed OR = 3.8 (95% CI 1.2-11.7). In analyses of females only, the magnitude of these associations was further increased. Conclusions: Respondents employed in precarious arrangements were more likely to report being exposed to UWSA, even after adjustment for age and gender. Implications: Greater protections from UWSA are likely needed for precariously employed workers. [source] Personal exposure to mobile communication networks and well-being in children,A statistical analysis based on a functional approachBIOELECTROMAGNETICS, Issue 4 2009Anja Kühnlein Abstract The MobilEe-study was the first cross-sectional population-based study to investigate possible health effects of mobile communication networks on children using personal dosimetry. Exposure was assessed every second resulting in 86,400 measurements over 24 h for each participant. Therefore, a functional approach to analyze the exposure data was considered appropriate. The aim was to categorize exposure taking into account the course of the measurements over 24 h. The analyses were based on the 480 maxima of each 3 min time interval. Exposure was classified using a nonparametric functional method. Heterogeneity of a sample of functional data was assessed by comparing the functional mode and mean of the distribution of a functional variable. The partition was built within a descending hierarchical method. The resulting exposure groups were compared with categories derived from a standard method, which used the average exposure over 24 h and set the cut-off at the 90th percentile. The functional classification resulted in a splitting of the exposure data into two groups. Plots of the mean curves showed that the groups could be interpreted as children with "low exposure" (88%) and "higher exposure" (12%). These groups were comparable with categories of the standard method. No association between the categorized exposure and well-being was observed in logistic regression models. The functional classification approach yielded a plausible partition of the exposure data. The comparability with the standard approach might be due to the data structure and should not be generalized to other exposures. Bioelectromagnetics 30:261,269, 2009. © 2009 Wiley-Liss, Inc. [source] Vibration exposure and disease in a shipyard: A 13-year revisitAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2004Martin Cherniack MD Abstract Background In a 1988 study of shipyard workers, a progressive association was observed between cumulative exposure to vibration and the vascular and neurological symptoms of the hand-arm vibration syndrome (HAVS). In 2001, after a decade of exposure reduction and ageing of the workforce, a second study at the same site was initiated. Methods In 2001, 214 subjects were selected; they represented four current weekly vibration exposure time intervals,0 hr, >0,<,5 hr, ,5,<,20 hr, ,20 hr. The 1988 and 2000 cross-sectional populations were compared on the basis of exposure duration and current symptoms. Results In 2001, the study population was 9.6 years older than the 1988 group. Current weekly exposure hours were similar in the low and medium exposure groups 2001 and 1988, but exposure was reduced by an average of 9.7 hr per week in the highest exposure group (,20 hr) in 2001. Symptom severity was regressed polychotomously on estimated exposure (log cumulative hours); the OR was weaker in 2001 than in 1988 for sensorineural symptoms,1.44 [CI 1.04,1.98] versus 2.35 [CI 1.48,3.73]. This was also true for vascular symptoms,1.70 [CI 1.06,2.71] versus 3.99 [CI 2.27,7.01]. Vascular symptoms were more prevalent in the highest lifetime vibration exposure group in 1988 (68.7 vs. 43.2% in 2001); sensorineural symptoms were more prevalent in the least vibration exposed group in 2001 (52.6 vs. 20.7% in 1988). Conclusions The prevalence of vascular symptoms associated with cumulative vibratory exposure was significantly greater in 1988, but neurological symptoms were more common at lower exposure levels in 2001. The presumption that reducing exposure duration alone is sufficient, in the absence of change in vibration magnitude, is not supported by the results of this study. Am. J. Ind. Med. 45:500,512, 2004. © 2004 Wiley-Liss, Inc. [source] | |||||||||||||