DIGIT PREFERENCE OF SYSTOLIC OR DIASTOLIC BLOOD PRESSURE AND THE ASSOCIATION WITH CARDIOVASCULAR EVENTS IN PATIENTS WITH TREATED HYPERTENSION IN PRIMARY CARE

Objective: Digit preference, the rounding of blood pressure (BP) values more frequently than expected by chance, is associated with fewer antihypertensive prescriptions and increased cardiovascular (CV) event risk. This study investigated how BP digit preference, specifically the recorded exact systolic and diastolic values (SBP, DBP) of 140 and 90 mmHg in patients with treated hypertension in primary care are associated with future CV events. Design and method: From the Swedish Primary Care Cardiovascular Database, 74,751 hypertensive patients (41,728 women) from 48 primary care centers were included. Two analyses were performed for patients with the most recent measurement of a SBP 136–144 mmHg or DBP 86–94 mmHg recorded during 2007–2008. The SBP was categorized as 136–139, 140mmHg, and 141–144 mmHg; DBP as 86–89, 90, and 91–94 mmHg. Cox proportional hazards regression models assessed associations with CV events (ischemic heart disease, cerebrovascular disease, and CV death) during 2009–2013, adjusting for age, sex, income, diabetes, ischemic heart disease, and cerebrovascular disease. Results: A total of 12,945 SBP and 8,73,7 DBP measurements were analyzed: 136–139 mmHg (19.7%), 140 mmHg (62.8%), and 141–144 mmHg (17.5%); and:86–89 mmHg (25.4%), 90 mmHg (63.8%), and 91–94 mmHg (10.9%). For SBP, compared to 140 mmHg, the risk of CV events was lower in the 136–139 mmHg group (HR=0.86; 95% CI: 0.75–0.98; p=0.03) and in the 141–144 mmHg group (HR=0.81; 95% CI: 0.70–0.93; p=0.002). For DBP, no significant associations were observed: 86–89 mmHg (HR=0.89; 95% CI: 0.77–1.04; p=0.15) and 91–94 mmHg (HR=1.05; 95% CI: 0.84–1.30; p=0.68) compared to 90 mmHg. Sex stratified analyses revealed no significant differences. Conclusions: An exact SBP of 140 mmHg and DBP of 90 mmHg are more common than expected by chance. The 140 mmHg group showed increased CV event risk, possibly due to inaccurate BP measurement, misinterpretation of BP levels, or suboptimal treatment decisions, indicating potential issues in quality of care.