When should hypertension be treated? The different perspectives of Canadian family physicians and patients.

BACKGROUND

Hypertension guidelines from different organizations often specify different treatment thresholds, and none explicitly state how these thresholds were chosen. This study was undertaken to determine the treatment thresholds of family physicians and hypertensive patients for mild, uncomplicated essential hypertension. A subject's treatment threshold can be determined by eliciting the minimum reduction in cardiovascular risk that he or she feels outweighs the inconvenience, costs and side effects of antihypertensive therapy (the minimal clinically important difference [MCID]).

METHODS

The study subjects consisted of a random sample of family physicians and a consecutive sample of hypertensive patients without overt cardiovascular disease from Ottawa and Edmonton. To determine participants' MCIDs, we used a survey employing hypothetical scenarios (each depicting a different baseline cardiovascular risk) and a probability trade-off tool.

RESULTS

Of 94 family physicians and 146 patients approached for the study, 72 and 74 participated respectively. There was marked variability in the MCIDs of both groups. In general, patients were less likely to want antihypertensive therapy than physicians, particularly when baseline cardiovascular risks were low: 49% v. 64% (p = 0.06), 68% v. 92% (p < 0.001) and 86% v. 100% (p = 0.001) for 5-year cardiovascular risks of 2%, 5% and 10% respectively. Moreover, patients expressed larger MCIDs (i.e., wanted greater benefits before accepting therapy) than physicians. However, a subgroup of patients (15% to 26%, depending on the scenario) wanted treatment even if there was no anticipated benefit. Multivariate analysis showed that no sociodemographic factors strongly predicted the MCIDs of either group.

INTERPRETATION

Guidelines that set treatment thresholds on the basis of physician or expert opinion may not accurately reflect the preferences of hypertensive patients. There is a need for patient decision aids and attention to patient preferences when initiation of antihypertensive therapy is considered for the prevention of cardiovascular disease. Further research is needed to define treatment thresholds for other chronic conditions and in other groups.