David R. Ragland

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BACKGROUND Physical activity is recommended by physicians to patients with non-insulin-dependent diabetes mellitus (NIDDM), because it increases sensitivity to insulin. Whether physical activity is effective in preventing this disease is not known. METHODS We used questionnaires to examine patterns of physical activity and other personal characteristics(More)
OBJECTIVE To determine the effect of comorbidity and stage of disease on 3-year survival in women with primary breast cancer. DESIGN Longitudinal, observational study. SETTING Metropolitan Detroit. PATIENTS 936 women ages 40 to 84 years. MEASUREMENTS Data on stage of breast cancer, treatment type, and comorbidity were obtained from Metropolitan(More)
STUDY DESIGN This study critically reviewed current conceptualizations of occupational disability resulting from low back pain (LBP). It proposes a new classification system for back pain built on a phase-model of disability. OBJECTIVES The goal was to develop a classification system that overcomes the shortcomings of existing classification schemes and(More)
BACKGROUND The etiologic role of biomechanical factors for low back injury (LBI) needs to be confirmed in prospective studies that control for psychosocial factors. METHODS Complete baseline information on 1,233 vehicle operators was gathered during medical examinations and by questionnaire. First LBI during 7.5 years of follow-up was ascertained from(More)
STUDY DESIGN Back and neck pain was studied cross-sectionally in 1,449 urban transit drivers by linking medical data, self-reported ergonomic factors, and company records on job history. OBJECTIVES The goal was to examine the relation between physical workload, ergonomic factors, and the prevalence of back and neck pain. SUMMARY OF BACKGROUND DATA(More)
BACKGROUND The influence of occupation and the worksite has emerged as an important area of study in research on alcohol consumption. Occupational and nonoccupational factors were studied in relation to alcohol consumption using data from a 1983-1985 cross-sectional study of transit operators. METHODS A total of 1.853 operators underwent a medical(More)
BACKGROUND To understand the consequences of driving cessation in older adults, the authors evaluated depression in former drivers compared with active drivers. METHODS Depression (as assessed using the Center for Epidemiological Studies Depression Scale), driving status, sociodemographic factors, health status, and cognitive function were evaluated for a(More)
OBJECTIVE A growing body of literature is documenting the health effects of racial discrimination. The authors investigated the association between racial discrimination and alcohol-related behavior in a sample of urban transit operators. METHODS Using data from a 1993-1995 cross-sectional study of transit operators in San Francisco, California, the(More)
Dichotomizing a continuous outcome variable casts that variable in traditional epidemiologic terms (that is, disease, no disease). One consequence is overall reduced statistical power. A more fundamental concern is that the magnitude of various measures of association (for example, prevalence ratio, odds ratio) and statistical power depend on the cutpoint(More)