An examination of the short-run relationship between blood pressure and physician utilization among hypertensive patients

Abstract

Background. Pharmacoeconomic studies of hypertension therapy have primarily focused on the long-term reductions in cardiovascular morbidity and mortality associated with blood pressure lowering, and the subsequent long-term savings associated with these reductions. There is a dearth of information regarding the impact of antihypertensive treatment on short-term costs. Methods. The objective of the analysis was to assess the relationship between blood pressure and physician utilization across three cross-sectional short-term periods (one year, two years, and three years). The sample included patients >18 years of age who had been diagnosed with hypertension prior to 2003. A two-stage multivariable modeling approach was used in the analysis. In the first stage, average SBP in a period was regressed against factors associated with blood pressure. Fitted estimates of average SBP from the first stage were used in the second stage model, which regressed count of physician days against the fitted SBP measure, as well as demographic and clinical variables of interest. Generalized linear models were used in both stages. Sensitivity analyses were conducted to test the assumptions made in the baseline model. Results. Across all three periods, there was a positive and significant (p<0.001) relationship between average systolic blood pressure and count of physician visits, controlling for other factors. Each 10 mmHg increase in average SBP was associated with approximately 0.24 more physician days over the one year period, 0.37 more physician days over the two year period, and 0.48 more physician days over the three year period in a hypothetical patient. Deviance from the mean SBP of the population was a significant predictor of physician visits (p<0.05) across the three periods. Sensitivity analyses indicated that the results were robust to changes in assumptions related to inclusion/exclusion criteria and blood pressure measurement used. Conclusion. The results of the analysis indicate that patients with higher blood pressure had a greater number of physician visits across the three short-term periods compared to patients with lower blood pressure. Future pharmacoeconomic analyses of hypertension and other chronic conditions should consider the potential short-term benefits of newer therapies, and managed care organizations should consider such benefits in formulary decision-making.