Background and Aim: Estimation of the odds ratio (OR) with logistic regression is a widely used approach to identify the risk factors of hypertension. Based on a cut-off point for blood pressure, this method decreases the efficiency and precision of the analysis. An alternative is to calculate OR with linear regression analysis, which is a more precise approach. The purpose of this study was to determine the prevalence of systolic and diastolic hypertension and the risk factors for hypertension by comparing the OR found with logistic and linear regression.

  Materials and Methods: In a cross-sectional study in 2005, 3997 persons in Shiraz were selected by random multistage sampling. The relationship between blood pressure and explanatory variables of interest including sex, age and body mass index was investigated by calculating the OR with both logistic and linear regression without dichotomizing. The data produced with both methods were compared through SPSS V.13 and S-PLUS 2000.

  Results: The age range of all patients included in our analysis was 18-99 years the prevalence of systolic hypertension was 10.8% and that of diastolic hypertension was 7.4%. Both OR calculation procedures detected a significant association with an increased risk of systolic and diastolic hypertension for sex, age and body mass index. Linear regression was more precise and had smaller confidence intervals than logistic regression.