Associations Between Systolic Interarm Differences in Blood Pressure and Cardiovascular Disease Outcomes and Mortality: Individual Participant Data Meta-Analysis, Development and Validation of a Prognostic Algorithm: The INTERPRESS-IPD Collaboration

Abstract

Systolic inter-arm differences in blood pressure have been associated with all-cause mortality and cardiovascular disease. We undertook individual participant data meta-analyses to 1) quantify independent associations of systolic inter-arm difference with mortality and cardiovascular events; 2) develop and validate prognostic models incorporating inter-arm difference, and 3) determine whether inter-arm difference remains associated with risk after adjustment for common cardiovascular risk scores. We searched for studies recording bilateral blood pressure and outcomes, established agreements with collaborating authors, and created a single international dataset (the INTERPRESS-IPD Collaboration). Data were merged from 24 studies (53,827 participants). Systolic inter-arm difference was associated with all-cause and cardiovascular mortality: continuous hazard ratios 1.05 (95% confidence interval 1.02 to; 1.08) and 1.06 (95% confidence interval 1.02 to 1.11) respectively per 5 mmHg systolic inter-arm difference. Hazard ratios for all-cause mortality increased with inter-arm difference magnitude from a ≥5 mmHg threshold (hazard ratio 1.07; 95% confidence interval 1.01 to 1.14). Systolic inter-arm differences per 5 mmHg were associated with cardiovascular events in people without pre-existing disease, after adjustment for ASCVD (hazard ratio 1.04; 95% confidence interval 1.00 to 1.08), Framingham (hazard ratio 1.04; 95% confidence interval 1.01 to 1.08), or QRISK2 (hazard ratio 1.12; 95% confidence interval 1.06 to 1.18) cardiovascular risk scores. Our findings confirm that systolic inter-arm difference is associated with increased all-cause mortality, cardiovascular mortality, and cardiovascular events. Blood pressure should be measured in both arms during cardiovascular assessment. A systolic inter-arm difference of 10 mmHg is proposed as the upper limit of normal.