Increased treatment of hypertension does not explain the decline in stroke mortality in the United States, 1970-1980.

The steady decline in mortality from stroke in the United States accelerated markedly in the 1970s. It has been widely assumed that an increase in the rate of treatment of hypertension is the most likely explanation for this major public health achievement. An analysis of available information, however, suggests that improvements in the community control of hypertension in the United States in the period 1970-1980 have contributed in only a minor way. There were 45,357 fewer deaths from stroke in 1980 among those aged 35-74 years than might have been expected if the death rates had stayed the same as in 1970. Data from the National Health and Nutrition Surveys indicate that six million more people received antihypertensive medication in 1980 than in 1970. Results from a pooled analysis of randomized controlled trials of the treatment of hypertension suggest that between 6% and 16% of the reduction in stroke mortality was due to the increased treatment of hypertension. Epidemiological observations indicate that between 16% and 25% of the overall decline in stroke mortality can be attributed to the treatment of hypertension, suggesting that clinical trials probably underestimate the community-wide benefits of treatment. These results also suggest that at least three quarters of the decline in stroke mortality in the United States in the period 1970-1980 is due to factors other than antihypertensive treatment.