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Medical Biomathematics and Biometrics Commons™
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Full-Text Articles in Medical Biomathematics and Biometrics
Prevalence, Incidence, And Persistence Of Major Depressive Symptoms In The Cardiovascular Health Study, Stephen M. Thielke Md, Ms, Paula Diehr Phd
Prevalence, Incidence, And Persistence Of Major Depressive Symptoms In The Cardiovascular Health Study, Stephen M. Thielke Md, Ms, Paula Diehr Phd
Paula Diehr
PURPOSE: To explore the association of major depressive symptoms with advancing age, sex, and self-rated health among older adults. DESIGN AND METHODS: We analyzed 10 years of annual assessments in a longitudinal cohort of 5888 Medicare recipients in the Cardiovascular Health Study. Self-rated health was assessed with a single question, and subjects categorized as healthy or sick. Major depressive symptoms were assessed using the Center for Epidemiologic Studies Short Depression Scale, with subjects categorized as nondepressed (score < 10) or depressed (> or =10). Age-, sex-, and health-specific prevalence of depression and the probabilities of transition between depressed and nondepressed states were estimated. RESULTS: The …
The Number Of Sick Persons In A Cohort, Paula Diehr
The Number Of Sick Persons In A Cohort, Paula Diehr
Paula Diehr
To see if the number of sick persons in a cohort was approximately constant over time, we calculated the number of sick persons in a “research” cohort of older adults followed for up to 14 years, and also in a synthetic birth cohort. Methods: In the research cohort, we calculated the actual number of persons in each health state over time, using eight different definitions of “sick”. For the birth cohort, we estimated the number of sick persons each year after birth. Results: The number of sick persons in the research cohort was approximately constant for 14 years, for all …
Probabilities Of Transition Among Health States For Older Adults, Paula Diehr
Probabilities Of Transition Among Health States For Older Adults, Paula Diehr
Paula Diehr
GOAL: To estimate the probabilities of transition among self-rated health states for older adults, and examine how they vary by age and sex. METHODS: We used self-rated health (excellent, very good, good, fair, poor, dead) collected in two longitudinal studies of older adults (mean age 75) to estimate the probability of transition in 2 years. We used the estimates to project future health for selected cohorts. FINDINGS: These older adults were most likely to be in the same health state 2 years later, but a substantial proportion changed in both directions. Transition probabilities varied by initial health state, age and …
Survival Versus Years Of Healthy Life; Which Is More Powerful As A Study Outcome?, Paula Diehr
Survival Versus Years Of Healthy Life; Which Is More Powerful As A Study Outcome?, Paula Diehr
Paula Diehr
Studies of interventions that are intended to improve patients' health are often evaluated with survival as the primary outcome, even when a measure adjusted for quality of survival, such as years of healthy life (YHL), would seem more appropriate. The purpose of this article is to determine whether studies based on survival are more or less powerful than studies based on YHL in clinical trials where either measure might be appropriate. We used data from the Cardiovascular Health Study (CHS) to estimate the sample size that would be needed in studies of 156 different health conditions, for the two outcome …
Predicting Future Years Of Healthy Life For Older Adults, Paula Diehr
Predicting Future Years Of Healthy Life For Older Adults, Paula Diehr
Paula Diehr
Cost-effectiveness studies often need to compare the cost of a program to the lifetime benefits of the program, but estimates of lifetime benefits are not routinely available, especially for older adults. We used data from two large longitudinal studies of older adults (ages 65-100) to estimate transition probabilities from one health state to another, and used those probabilities to estimate the mean additional years of healthy life that an older adult of specified age, sex, and health status would experience. We found, for example, that 65-year-old women in excellent health can expect 16.8 years of healthy life in the future, …
Effect Size And Power For Clinical Trials Using Years Of Healthy Life As The Primary Endpoint, Paula Diehr
Effect Size And Power For Clinical Trials Using Years Of Healthy Life As The Primary Endpoint, Paula Diehr
Paula Diehr
Some clinical trials perform repeated measurements on patients over time, plot those measures against time, and summarize the results in terms of the area under the curve. If the measured variable is health status, the summary outcome is sometimes referred to as years of healthy life (YHL), or quality-adjusted life years (QALY). This paper investigates some theoretical and practical aspects of randomized trials designed to assess measures such as YHL. We first derived algebraic expressions for the effect size of YHL measures under several theoretical models of the treatment's effect on health. We used these expressions to examine how the …