Association between chlorthalidone treatment of systolic hypertension and long-term survival

Abstract

Context: In the Systolic Hypertension in the Elderly Program (SHEP) trial, conducted between 1985 and 1990, antihypertensive therapy with chlorthalidone-based stepped-care therapy resulted in a lower rate of cardiovascular events than placebo but effects on mortality were not significant.

Objective: To study the gain in life expectancy of participants randomized to active therapy at the 22-year follow-up.

Design, setting, and participants: A National Death Index ascertainment of death in the long-term follow-up of a randomized, placebo-controlled, clinical trial (SHEP) of patients aged 60 years or older with isolated systolic hypertension. Recruitment was between March 1, 1985, and January 15, 1988. After the end of a 4.5-year randomized phase of the SHEP trial, all participants were advised to receive active therapy. The time interval between the beginning of recruitment and the ascertainment of death by National Death Index (December 31, 2006) was approximately 22 years (21 years 10 months).

Main outcome measures: Cardiovascular death and all-cause mortality.

Results: At the 22-year follow-up, life expectancy gain, expressed as the area between active (n = 2365) and placebo (n = 2371) survival curves, was 105 days (95% CI, -39 to 242; P = .07) for all-cause mortality and 158 days (95% CI, 36-287; P = .009) for cardiovascular death. Each month of active treatment was therefore associated with approximately 1 day extension in life expectancy. The active treatment group had higher survival free from cardiovascular death vs the placebo group (hazard ratio [HR], 0.89; 95% CI, 0.80-0.99; P = .03) but similar survival for all-cause mortality (HR, 0.97; 95% CI, 0.90-1.04; P = .42). There were 1416 deaths (59.9%) in the active treatment group and 1435 deaths (60.5%) in the placebo group (log-rank P = .38, Wilcoxon P = .24). Cardiovascular death was lower in the active treatment group (669 deaths [28.3%]) vs the placebo group (735 deaths [31.0%]; log-rank P = .03, Wilcoxon P = .02). Time to 70th percentile survival was 0.56 years (95% CI, -0.14 to 1.23) longer in the active treatment group vs the placebo group (11.53 vs 10.98 years; P = .03) for all-cause mortality and 1.41 years (95% CI, 0.34-2.61; 17.81 vs 16.39 years; P = .01) for survival free from cardiovascular death.

Conclusion: In the SHEP trial, treatment of isolated systolic hypertension with chlorthalidone stepped-care therapy for 4.5 years was associated with longer life expectancy at 22 years of follow-up.