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.