Are Observational Studies More Informative Than Randomized Controlled Trials in Hypertension?

Abstract

Cardiovascular (CV) disease is the major cause of death and disability in United States, as well as in Europe1,2: It contributes substantially to the escalating costs of health care. Over the past 10 years, the control of CV risk factors has improved especially at the older age strata,3 but most of this success does not seem to be related to a reduced impact of hypertension.4,5 As recently pointed out,6,7 the reduction of hypertension-associated CV morbidity and mortality is almost exclusively a consequence of the results of randomized controlled trials (RCTs), especially those comparing active medications versus placebo.8 Unfortunately, despite this success, arterial hypertension remains the leading CV risk factor, to which 13% of global death is attributable.9 Uncontrolled blood pressure (BP) is one of the most frequent problems encountered in the prevention of CV diseases.10 Hypertension control has improved over time, but it is evident that this improvement is still insufficient.11 Half of the patients do not achieve normalization of BP values, a rate that is especially high in elderly subjects,12 an evidence based on analyses of effectiveness of antihypertensive therapy and of population-based cohorts.3,13 Although most RCTs on antihypertensive medications present positive results, only a minority of them report the proportion of optimal BP control achieved with the treatment (Table 1). Overall, with a few exceptions,23,27,33 efficacy of antihypertensive therapy also does not seem optimal in the studies declaring proportion of achieved target BP. View this table: Table 1. List of 19 Major Trials on Antihypertensive Therapy With Average Initial and Final Blood Pressure Values (When Reported) RCTs largely offset a number of biases encountered in the real-world physician’s decision making, are unavoidable in analyses of even large clinical databases, …