A population-based study of need for changes and continuing rates of antihypertensive drugs

BACKGROUND: Antihypertensive drugs are frequently changed because of ineffi cacy and adverse effects. The aim of this study was to compare the incidenc e of changes of the new classes of drugs from the classical beta -blockers and diuretics. We also have calculated the probability of continuing with e ach class of drug. MATERIAL AND METHOD: Clinical reports of hypertensive patients of a general practice centre were examined. All changes of treatment and their causes w ere registered between october 1997 and september 1999. The incidences for global changes and also for intolerance and ineficacy changes were calculat ed for each drug. Relative risks for beta -blockers, diuretics, ACE inhibit ors of anhidride carbonic enzyme and angiotensine II-receptor-antagonists w ere analized, The cumulated probability for continuing therapy was also stu died. RESULTS: 27.6% out of 786 courses of treatment were changed, 51.4% due to i ntolerance and 29,8% due to inefficacy. The probability for continuing was 88% after 3 months, 81% after 6 months, 71% after one year and 54% after 2 years. The probability for discontinuing because of intolerance was higher in the first 3 months (51%), but afterwards it remained stable along the ti me. CONCLUSIONS: Anthypertensive drugs are discontinued more frequently than wh at it would be desirable and their continuing rates are low. Differences ob served among each class of drugs are not argument enough for changing the g eneral recommendation of using beta -blockers and diuretics as first choice drugs for initial treatment of hypertension.