Long-term survival in the randomized trial of drug treatment in mild to moderate hypertension of the Oslo study 1972–3

• Thiazide treatment of mild to moderate hypertension may have had an adverse effect on MI mortality.
• After 15 years follow-up changes in treatment practices may have improved prognosis.
• Equal mortality in groups the last 10 years possibly due to the equal use of antihypertensive treatment.
• Cerebrovascular 40-year mortality was non-significantly reduced.
• No difference in 40-year total mortality between treatment groups.

BackgroundIn the Oslo cardiovascular study of 1972–3 a 5-year randomized trial in mild to moderate hypertension was performed. Several changes in treatment practices have been recommended since that time. We followed the mortality patterns up to 40 years.MethodsInvited to the Oslo study screening were 25,915 middle-aged men and 16,203 (63%) participated. Reexaminations were done to select suitable participants into the trial. Men had blood pressure 150–179/95–109 mm Hg and the active group (n = 406) was treated with thiazides, alpha-methyldopa and propranolol versus untreated controls (n = 379). Cox regression analysis was used for statistical analyses.ResultsThere was no trend towards reduction in total mortality by treatment. A nominally significant increase in risk of death at first myocardial infarction was observed in the trial treatment group across the follow-up period, HR = 1.51 (1.01–2.25); (P = 0.042). The excess risk developed rapidly during the first 15 years, but the gap between the groups diminished to a large extent during the next 15 years, but the curves stayed at a certain distance for the last 10 years. Cerebrovascular death tended to be non-significantly reduced, HR = 0.85 (0.52–1.41).ConclusionsDrug treatment of mild hypertensive men initiated in the 1970s did not reduce mortality at first MI or total mortality. However, during the period (late 1980s and whole 1990s), when large changes in hypertension treatment practices occurred into regimes with more use of combination therapies including metabolically neutral drugs at lower doses, beneficial effects on MI mortality could be observed.