Several authors have reported hypertension, smoking and hypercholesterolemia as independent risk factors to ischaemic heart disease (IHD). However few of them have investigated the existence of a linear gradient related to the levels of these exposures and IHD. The effect of different levels of these exposures and IHD after adjusting for known confounders of effect, is assessed. The project was designed as a case-control study and the data were collected over one year from March/93 to February/94. The sample was composed of a total of 833 individuals of both genders aged 30-69 living in the city of S. Paulo, SP (Brazil), 280 of whom were compared with 553 controls (285 neighbourhood controls and 268 hospital controls). Logistic regression was the statistical method wold for the analysis of the data. The results showed a linear gradient for known duration of hypertension and daily number of cigarettes consumed. Although the variables duration of hypercholesterolemia and duration of the habit smoking presented statistically significant odds ratio in the respective strata there was no indication of a linear gradient. Some methodological issues are presented to explain this absence of a linear gradient for known duration of hypercholesterolemia and duration of the smoking habit. It is concluded that the dose response effect detected for known duration of hypertension and daily number of cigarettes consumed were independent of the presence of major risk factors ischaemic heart disease.
Myocardial ischemia; Case-control studies; Risk factors
