Molecular epidemiologic studies suggest genetic factors in the etiology of smoking behavior. Dopamine receptor genes, transporter genes (serotonin and dopamine), and other genes related to metabolism of nicotine are plausible functional candidate genes. Research examining the role of allelic variation in those genes is being actively pursued with respect to nicotine dependence as well as personality char-acteristics and mental disorders. Some of these genes were reported to be connected with schizophrenia. Although nicotine dependence itself is one of the mental disorders according to the fourth edition of Diagnostic and Statistical Manual of Mental Disorders and the World Health Organization's International Statistical Classification of Diseases and Related Health Problems-10 nomenclature, the high comor-bidity between nicotine dependence and other mental disorders such as schizophrenia or affective disorders has been noted. Therefore, the relationship between those mental disorders and tobacco addiction should be cleared up considering the interactive effect of genetic and environmental factors. J Epidemiol 2003;13:183-192.
Background: Two methods for selecting controls in nested case-control studies - matching on Xand counter matching on X - are compared when interest is in interaction between a risk factor X measured in the full cohort and another risk factor Z measured only in the case-control sample. This is important because matching provides efficiency gains relative to random sampling when X is uncommon and the interaction is positive (greater than multiplicative), whereas counter matching is generally efficient compared to random sampling. Methods: Matching and counter matching were compared to each other and to random sampling of controls for dichotomous X and Z Comparison was by simulation, using as an example a published study of radiation and other risk factors for breast cancer in the Japanese atomic-bomb survivors, and by asymptotic relative efficiency calculations for a wide range of parameters specifying the prevalence of X and Z as well as the levels of correlation and interaction between them. Focus was on analyses utilizing general models for the joint risk of X and Z. Results: Counter-matching performed better than matching or random sampling in terms of efficiency for inference about interaction in the case of a rare risk factor X and uncorrelated risk factor Z. Further, more general, efficiency calculations demonstrated that counter-matching is generally efficient relative to matched case-control designs for studying interaction. Conclusions: Because counter-matched designs may be analyzed using standard statistical methods and allow investigation of confounding of the effect of X, whereas matched designs require a non-stan- dard approach when fitting general risk models and do not allow investigating the adjusted risk of X, it is concluded that counter-matching on X can be a superior alternative to matching on X in nested case- control studies of interaction when X is known at the time of case-control sampling. J Epidemiol 2003;13:193-202.
BACKGROUND: Little is known about the impact of social demographic factors on post-discharge mortality among the hospitalized elderly. METHODS: A one-year prospective study was conducted in a random sample of 646 male patients aged 65 or older who were discharged from a university affiliated Veterans Administration Hospital at Little Rock, AR, USA. Within 48 hours of admission, each subject completed a standardized diagnostic evaluation. Mortality was recorded for all causes. Associations between patient characteristics at hospital discharge and mortality were identified utilizing univariable and multivariable (Cox proportional hazard regression) statistical techniques. RESULTS: The mean (SD) age was 73(±6) years. Within one year of hospital discharge, 83 patients (13%) died. Multiple social demographic factors were significantly associated with mortality in univariable analysis. After controlling for age, Katz index of ADL score, Charlson co-morbidity index and length of hospitalization, risk of one-year post-discharge mortality remained significantly associated with marital status, race, education, and occupational class. When all of the social demographic factors were included in a stepwise procedure, marital status, education and occupational class were selected as the strongest predictors of mortality. The adjusted hazard ratios (95% confidence interval) of mortality associated with non-married status, education <6 years, and history of having a blue-collar occupation were 2.01 (1.29-3.15), 1.86 (1.05-3.32), and 2.16 (1.03-4.54) respectively. CONCLUSION: The results suggest that social demographic factors are independent determinants of mortality among elderly patients. These factors should be used as important indices in identifying patients at higher risk of death in clinical assessments and in prevention programs for elderly patients after hospital discharge. J Epidemiol 2003; 13 :203-210.
Background: In Inner Mongolia, China, more than 300, 000 people are chronically exposed to arsenic via their drinking water. We have previously reported that the prevalence of arsenical dermatosis was as high as 40% in the Hetao Plain area. However, the association between exposure to arsenic in drinking water and adverse health effects has not been fully examined. The purpose of this study was to examine the association between exposure to arsenic and prevalence of subjective symptoms. Methods: A cross-sectional study was carried out in 431 residents of an arsenic-affected village and 189 residents of an arsenic-free village in 1996. Health-related interviews and physical examinations were conducted. The odds ratio for each subjective symptom was estimated, comparing residents of arsenic-free and affected villages. Results: An arsenic level of 50+ jig/L was found in 90.6% of wells in the arsenic-affected village. Adjusted odds ratios of subjective symptoms, including coughs (odds ratio [OR]=12.8, 95% confidence interval [CI]: 6.4-25.6), stomachaches (OR=5.8, 95% CI: 3.6-9.4), palpitations (OR=3.6, 95% CI: 1.5-8.2), urination problems (OR=14.7, 95% Cl: 3.3-65.5) and spontaneous abortions (OR=2.7, 95% CI: 0.8-8.4), were markedly higher amongst residents of the arsenic-affected village, including those without arsenic dermatosis. Conclusions: The present study shows a high prevalence of subjective symptoms amongst residents of an arsenic-affected village. Symptoms occurred in people with and without arsenic dermatosis. Our findings suggest that symptoms other than dermatosis should be considered when a clinical diagnosis of arsenic toxicosis is made. J Epidemiol 2003;13:211-215.
Background: Although epidemiologic studies including the Japan Public Health Center-based Prospective Study on Cancer and Cardiovascular Disease (JPHC study) have frequently used the basic health examination participants as study subjects, their background characteristics have rarely been investigated. The aim of this study is to clarify the background characteristics of participants and to discuss their impact on epidemiologic studies. Methods: Subjects were 43, 140 (Cohort I) and 34, 892 (Cohort II) respondents aged 40-59 years who completed a self-administered questionnaire in 1990 or 1993-94 by the JPHC Study. Respondents whose data of the basic health examination were also available were defined as participants. We com-pared their sociodemographic factors, personal medical history, and lifestyle-related factors with those of non-participants. Results: Participants tended to be older and less educated. They were more likely to engage in agri- culture, forestry and fisheries or to be self-employed persons, or homemakers. Male participants smoked less and were more likely to drink alcohol beverage moderately. Female participants smoked and drank less but tended to participate more in sports and physical exercise in their leisure time. Both male and female participants tended to eat fruits and green vegetables more often than non-partici-pants. In short, participants had a different socioeconomic status from non-participants and a favorable lifestyle profile, especially among women. These findings were principally consistent between the two cohorts. Conclusion: These differences between participants and non-participants in the basic health exami- nation might cause a selection bias that limits the application of the results to only participants in the basic health examination. J Epidemiol 2003;13:216-225.
Background: Although the fact that smoking habits have adverse effects on health, whether the high proportion of smokers elevates the prevalence of symptoms relating to the smoking in a community is still unknown. Methods: An ecologic study about whole Japan was conducted. Age-adjusted smoking prevalence was calculated using the National Nutrition Survey data from 1986 through 1995 by prefecture and sex. Age-adjusted respiratory symptom prevalence were observed using the National Life-style Survey data in 1995. Correlation among 46 and/or 43 prefectures was examined by sex. Results: There was a negative correlation between smoking prevalence and wheezing prevalence among males (r=-0.301). Among females, positive correlations were observed on the symptoms of nasal obstruction (r=0.355), nasal discharge (r=0.344), sore throat (r=0.481), cough (r=0.350), sputum (r=0.594), wheezing (r=0.451), palpitation (r=0.363), dyspnea (r=0.587), and frontal chest pain (r=0.472). Conclusions: Smoking prevalence was deeply related to respiratory symptoms among females in Japan. J Epidemiol2003;13:226-231.