Biomedical subjects

K P Kleinman

Publications and source records attributed to K P Kleinman.

7 recordsLinked to original sources

PubMed2000

Erectile dysfunction and coronary risk factors: prospective results from the Massachusetts male aging study.

BACKGROUND: Erectile dysfunction (ED), a wide spread and troublesome condition among middle-aged men, is partly vascular in origin. In the Massachusetts Male Aging Study, a random-sample cohort study, we investigated the relationship between baseline risk factors for coronary heart disease and subsequent ED, on the premise that subclinical arterial insufficiency might be manifested as ED. METHODS: Men ages 40-70, selected from state census lists, were interviewed in 1987-1989 and reinterviewed in 1995-1997. Data were collected and blood was drawn in participants' homes. ED was assessed from responses to a privately self-administered questionnaire. Analysis was restricted to 513 men with no ED at baseline and no diabetes, heart disease, or related medications at either time. RESULTS: Cigarette smoking at baseline almost doubled the likelihood of moderate or complete ED at followup (24% vs. 14%, adjusted for age and covariates, P = 0.01). Cigar smoking and passive exposure to cigarette smoke also significantly predicted incident ED, as did overweight (body-mass index > or =28 kg/m(2)) and a composite coronary risk score. Weaker prospective associations were seen for hypertension and dietary intake of cholesterol and unsaturated fat. CONCLUSIONS: Erectile dysfunction and coronary heart disease share some behaviorally modifiable determinants in men who, like our sample, are free of manifest ED or predisposing illness. Open questions include whether modification of coronary risk factors can prevent ED and whether ED may serve as a sentinel event for coronary disease.

Adult↗

PubMed2000

Socioeconomic factors and incidence of erectile dysfunction: findings of the longitudinal Massachussetts Male Aging Study.

Despite the well-documented relationship of socioeconomic factors (SEF) to various health problems, the relationship of SEF to erectile dysfunction (ED) is not well understood. As such, the goals of this paper are: (1) to determine whether incident ED is more likely to occur among men with low SEF; and (2) to determine whether incident ED varies by SEF after taking into consideration other well-established ED risk factors that are also associated with SEF such as smoking, diabetes, and high blood pressure. We used data from 797 participants in the longitudinal population-based Massachusetts Male Aging Study (baseline 1987-1989, follow-up 1995-1997) who were free of ED at baseline and had complete data on ED and all risk factors. ED was determined by a self-administered questionnaire and its relationship to SEF was assessed using logistic regression. We first analyzed the age-adjusted relationship of education, income, and occupation to incidence of ED. The results show that men with low education (O.R. = 1.46, 95% C.I. = 1.02-2.08) or men in blue-collar occupations (O.R. = 1.68, 95% C.I. = 1.16-2.43) are significantly more likely to develop ED. For the multivariate model, due to multicollinearity among education, income, and occupation, we ran three separate models. After taking into consideration all the other risk factors--age, lifestyle and medical conditions--the effect of occupation remained significant. Men who worked in blue-collar occupations were one and a half times more likely to develop ED compared to men in white-collar occupations (O.R. = 1.55, 95% C.I. = 1.06-2.28).

Aged↗

PubMed2000

A new surrogate variable for erectile dysfunction status in the Massachusetts male aging study.

Erectile dysfunction (ED) is the subject of a vast clinical literature, but little information has been gathered from random samples of the general public. The Massachusetts Male Aging Study (MMAS) addressed this important aspect of men's health. The MMAS was conducted in two waves, with baseline data collection in 1987-1989 and follow-up in 1995-1997. Subsequent to the baseline MMAS survey, a consensus developed that subjective measures are optimal for defining ED. Unfortunately, the baseline questionnaire did not ask subjects directly about their erectile functioning. Thus, we previously assigned the MMAS subjects a degree of impotence at baseline using a series of related questions, employing a discriminant formula constructed from a separate sample of urology clinic patients. At follow-up the men classified themselves directly in addition to answering the original series of related questions. In the present article, we report the results of a new discriminant function, based on the MMAS men at follow-up. We also compare the two methods and discuss our reasons for preferring the internally calibrated method.

Cross-Sectional Studies↗

PubMed2000

Incidence of erectile dysfunction in men 40 to 69 years old: longitudinal results from the Massachusetts male aging study.

PURPOSE: We estimated the incidence of erectile dysfunction in men 40 to 69 years old at study entry during an average 8.8-year followup, and determined how risk varied with age, socioeconomic status and medical conditions. MATERIALS AND METHODS: Data from a randomly sampled population based longitudinal study of Massachusetts men were analyzed. A total of 1,709 men completed the baseline interview during 1987 to 1989 and 1,156 survivors completed followup from 1995 to 1997. The analysis sample consisted of 847 men without erectile dysfunction at baseline and with complete followup information. Erectile dysfunction was assessed by discriminant analysis of 13 questions from a self-administered sexual function questionnaire and a single global self-rating question. RESULTS: The crude incidence rate for erectile dysfunction was 25.9 cases per 1,000 man-years (95% confidence interval [CI] 22.5 to 29.9). The annual incidence rate increased with each decade of age and was 12.4 cases per 1,000 man-years (95% CI 9.0 to 16.9), 29.8 (24.0 to 37.0) and 46.4 (36.9 to 58.4) for men 40 to 49, 50 to 59 and 60 to 69 years old, respectively. The age adjusted risk of erectile dysfunction was higher for men with lower education, diabetes, heart disease and hypertension. Population projections for men 40 to 69 years old suggest that 17,781 new cases of erectile dysfunction in Massachusetts and 617,715 in the United States (white males only) are expected annually. CONCLUSIONS: Although prevalence estimates and cross-sectional correlates of erectile dysfunction have recently been established, incidence estimates were lacking. Incidence is necessary to assess risk, and plan treatment and prevention strategies. The risk of erectile dysfunction was about 26 cases per 1,000 men annually, and increased with age, lower education, diabetes, heart disease and hypertension.

Adult↗

PubMed1998

A semi-parametric Bayesian approach to generalized linear mixed models.

The linear mixed effects model with normal errors is a popular model for the analysis of repeated measures and longitudinal data. The generalized linear model is useful for data that have non-normal errors but where the errors are uncorrelated. A descendant of these two models generates a model for correlated data with non-normal errors, called the generalized linear mixed model (GLMM). Frequentist attempts to fit these models generally rely on approximate results and inference relies on asymptotic assumptions. Recent advances in computing technology have made Bayesian approaches to this class of models computationally feasible. Markov chain Monte Carlo methods can be used to obtain 'exact' inference for these models, as demonstrated by Zeger and Karim. In the linear or generalized linear mixed model, the random effects are typically taken to have a fully parametric distribution, such as the normal distribution. In this paper, we extend the GLMM by allowing the random effects to have a non-parametric prior distribution. We do this using a Dirichlet process prior for the general distribution of the random effects. The approach easily extends to more general population models. We perform computations for the models using the Gibbs sampler.

Bayes Theorem↗

PubMed1998

A Bayesian framework for intent-to-treat analysis with missing data.

In longitudinal clinical trials, one analysis of interest is an intention-to-treat analysis, which groups subjects according to the randomized treatment regardless of whether they stayed on that treatment or not. When in addition to going off the randomized treatment subjects may also drop out of the study and be lost to follow-up, it is unclear what an intention-to-treat analysis should be. If measurements are made after treatment drop-out on a random sample of subjects who drop the treatment, then Hogan and Laird (1996, Biometrics 52, 1002-1017) present a random effects model, well suited to this type of analysis, which fits a two-piece linear spline to the data with the knot at the time the assigned treatment is dropped. This article presents a Bayesian approach to fitting a similar two-piece linear spline model and shows how the model can be applied to data that have no off-treatment observations.

Acquired Immunodeficiency Syndrome↗

PubMed1998

A semiparametric Bayesian approach to the random effects model.

In longitudinal random effects models, the random effects are typically assumed to have a normal distribution in both Bayesian and classical models. We provide a Bayesian model that allows the random effects to have a nonparametric prior distribution. We propose a Dirichlet process prior for the distribution of the random effects; computation is made possible by the Gibbs sampler. An example using marker data from an AIDS study is given to illustrate the methodology.

Acquired Immunodeficiency Syndrome↗