Hypertension is the most important risk factor of mortality, accounting for about 12% of all deaths worldwide. Time and again, lowering BP has proved to be beneficial in randomized controlled trials.
Still, a number of questions remain about the effects of antihypertensive therapy in patient groups that are excluded from most clinical trials. One should be cautious about extrapolating the findings of general population studies to special patient groups, especially if observational studies suggest a reversed risk factor pattern in these groups. Prime examples are the elderly and patients with CKD, in whom BP and the risk of death are often inversely related.
Two recently published studies have added to our knowledge of the effect of antihypertensive therapy in these groups. The Hypertension in the Very Elderly trial (HYVET) studied the effect of antihypertensive therapy on fatal or non-fatal stroke, all-cause mortality, cardiovascular mortality, and congestive heart failure in 3,845 hypertensive patients older than 80 years of age.
Patients were treated to a goal BP of 150/80 mm Hg by administering either indapamide followed by titrated doses of perindopril, or placebo. Treated patients experienced a reduction in all end points. It is unclear if the findings of the HYVET study can be applied to elderly patients with higher degrees of comorbidity (only 11% of those enrolled in HYVET had CVD), or if further BP lowering can result in additional benefits (since the BP goal in HYVET was higher than the currently recommended target for the general population).
Finally, it is unclear if the same benefits could be achieved with other types of antihypertensive regimens.
The second study was a sub-analysis of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), which studied the ef-fect of perindopril with added indapamide, on the risk of stroke in 1,757 patients with prior cerebrovascular disease and CKD.
Results showed a significant reduction in the incidence of recurrent strokes in treated patients. It remains unclear, however, if antihypertensive therapy in CKD could have benefits for other outcomes such as mortality and if these results can be applied to dialysis patients or to patients with CKD without prior cerebrovascular disease.
The contradiction between the results of observational studies of the general population and studies examining specific populations such as CKD patients can only be resolved by more similarly well conducted clinical trials.