Journal of chronic diseases最新文献

This paper presents at an instructive level detailed design, decision and computational aspects of p-values and power for clinical trials in which interim looks at accumulating data are planned. Background theory and an application are presented. In addition, a definition of the term p-value, appropriate for a trial in which interim looks are planned is proposed. The definition is intuitively consistent with that for a fixed sample size trial. That is, the p-value reflects the strength of the data against the null hypothesis. For trials incorporating group sequential methods, the p-value at a particular look reflects the conditional nature of the data collected through that look on the data collected through earlier looks.

A cross-sectional study was conducted to identify predictors of tardive dyskinesia (TD) in a group of 180 psychiatric outpatients maintained on neuroleptic medications. The estimated prevalence of this involuntary movement disorder was 33% in the total study population. Using multiple logistic regression, we found that TD was independently related to five factors: being 55 yr of age and older; being male; using depot (injectable) neuroleptics; having 6 or more years of neuroleptic exposure; and having less than 6 months of psychiatric hospitalization. In addition, the effect of depot medication was much greater in white males than it was in other race-sex groups. We observed no other interaction effects between pairs of predictor variables, nor did we find significant independent effects of race, denture use, DSM III diagnosis, current neuroleptic dose and potency, percent time on neuroleptics, and recent use of antiparkinsonian drugs or lithium. This study is serving as a pilot investigation for a large prospective incidence study that has already begun among patients at risk of developing TD in the same source population.

Cross-sectional and prospective associations between lung function and potential determinants were examined in the Framingham Study. Personal characteristics of interest were body height and weight, hand grip strength, smoking habits, history of respiratory symptoms and disease, and hematocrit.

Baseline pulmonary function was the most powerful indicator of future FEV₁ and cigarette smoking was the most important correctable influence. In addition to baseline FEV₁, FVC and smoking habits, the important predictors of future lung function were age, relative weight, respiratory symptoms and hematocrit. There was a higher follow-up FEV₁ in those who quit smoking compared to those who continued even after adjustment for other associated variables. Relative weight and hematocrit were associated with FEV₁ measured 14 years after baseline (directly for relative weight and inversely for hematocrit).

Several methods have been proposed for standardizing risks, risk ratios, and risk differences based on the results of logistic regression. These methods provide an alternative to direct standardization, a particularly useful approach when there are many covariates. In this paper, methods for calculating approximate confidence limits for these standardized measures are presented. A simple example, in which published data are used, illustrates the techniques and allows comparison with confidence limits calculated from the directly standardized risk ratio.

Six thousand six hundred thirty two subjects, employed in 420 small and medium-sized companies in the Paris region were examined in a cross-sectional study. Their alcohol consumption, as obtained by interview was found to be higher among males than among females, among workers than among managers, executives, and clerks. Alcohol consumption was positively associated with age, body mass index, coffee and cigarette consumption, occupational exposure to noise and working nights or alternating shifts. A positive, continuous, relationship was observed, for men and women, between alcohol intake and both systolic and diastolic blood pressure. This association was highly significant in the multivariate analysis (multiple linear regression) where alcohol intake, following age and body mass index, was the third predictive factor of blood pressure level in the stepwise regression. The positive association between alcohol consumption and prevalence of arterial hypertension was aggravated by the poor control of hypertension which was found among drinkers. Awareness of hypertension, compliance with an antihypertensive treatment and its efficacy, were negatively associated withg alcohol intake. The findings stress the importance of alcohol consumption which was found to be a major risk factor for arterial hypertension and noncompliance with antihypertensive treatment in this population.