Effect of intensive versus standard clinic-based blood pressure management on ambulatory blood pressure - results from the sprint abpm study

Abstract

The Systolic Blood Pressure Intervention Trial (SPRINT) was a 2-arm, multicenter, randomized clinical trial designed to test whether a treatment program aimed at reducing systolic blood pressure (SBP) to a lower goal than currently recommended will reduce cardiovascular disease. The goal of the SPRINT Ambulatory BP Ancillary Study was to evaluate the effect of intensive (SBP <120 mmHg) versus standard (SBP <140 mmHg) clinic-based BP targets on ambulatory BP, specifically nighttime SBP (primary outcome). Ambulatory BP was measured within 3 weeks of the 27 month follow-up visit in 876 participants at 15 SPRINT clinic sites. Spacelabs 90207 monitors were programmed to record BP every 30 minutes. Clinic BP was obtained after 5 minutes of rest using an automated device (Model 907, Omron Healthcare); the mean of three BP measurements was used for analyses. Average age at the time of ABPM was 71.5 years, 29% were female, 28% were black, and the average eGFR was 69.7 ml/min/1.73m2. Clinic and ambulatory BP (in mmHg) at the time of ABPM and group differences (standard-treatment minus intensive-treatment) are shown in the table. Additionally, Bland-Altman plots indicated poor concordance between office and daytime ambulatory BP with a Pearson correlation of 0.54 and limits of agreement of approximately -20 to 30 mmHg. In conclusion, a treatment regimen targeting office based SBP less than 120 mmHg lowers 24hr, daytime, and nighttime ambulatory BP and BP variability, but does not alter diurnal BP pattern (night/day BP ratio). Ambulatory BP monitoring confirms a large and significant BP difference between randomized groups despite the intervention being based on clinic BP. The difference in BP between intensive and standard clinic based BP targets was greater when measured with clinic than with 24 hour ambulatory BP, and daytime compared to nighttime BP. Given the poor agreement between clinic and 24 hour BP, ambulatory BP monitoring may be required to assess the effect of targeted hypertension therapy on out of office BP. Further studies are needed to assess whether targeting hypertension therapy based on ambulatory BP would reduce adverse outcomes compared to targeting clinic BP.