Impact of a system-wide quality improvement initiative on blood pressure control: a cohort analysis

Objective To assess the impact of a quality improvement programme on blood pressure (BP) control and determine whether medication intensification or repeated measurement improved control. Design Retrospective cohort comparing visits in 2015 to visits in 2016 (when the programme started). Subjects Adults with ≥1 primary care visit between January and June in 2015 and 2016 and a diagnosis of hypertension in a large integrated health system. Measures Elevated BP was defined as a BP ≥140/90 mm Hg. Physician response was defined as: nothing; BP recheck within 30 days; or medication intensification within 30 days. Our outcome was BP control (<140/90 mm Hg) at the last visit of the year. We used a multilevel logistic regression model (adjusted for demographic and clinical variables) to identify the effect of the programme on the odds of BP control. Results Our cohort included 111 867 adults. Control increased from 72% in 2015 to 79% in 2016 (p<0.01). The average percentage of visits with elevated blood pressure was 31% in 2015 and 25% in 2016 (p<0.01). During visits with an elevated BP, physicians were more likely to intensify medication in 2016 than in 2015 (43% vs 40%, p<0.01) and slightly more likely to obtain a BP recheck (15% vs 14%, p<0.01). Among patients with ≥1 elevated BP who attained control by the last visit in the year, there was 6% increase from 2015 to 2016 in the percentage of patients who received at least one medication intensification during the year and a 1% increase in BP rechecks. The adjusted odds of the last BP reading being categorised as controlled was 59% higher in 2016 than in 2015 (95% CI 1.54 to 1.64). Conclusion A system-wide initiative can improve BP control, primarily through medication intensification.