Blood Pressure Control Among Black and White Adults Following a Quality Improvement Program in a Large Integrated Health System

IMPORTANCE: A higher percentage of non-Hispanic Black (hereinafter, Black) adults vs non-Hispanic White (hereinafter, White) adults with hypertension have uncontrolled blood pressure (BP) contributing to racial and ethnic disparities in cardiovascular disease. In 2010, Kaiser Permanente Southern California began implementing quality improvement (QI) strategies aimed at reducing this disparity. OBJECTIVE: To examine the change in BP control between Black and White patients before and after the implementation of a QI program. DESIGN, SETTING, AND PARTICIPANTS: A QI quasi-experimental, difference-in-difference analysis was conducted of Kaiser Permanente Southern California patients 18 years or older included in the population care management hypertension registry. The study was conducted from December 31, 2008, to December 31, 2019. Data analysis was performed from November 20, 2020, to November 7, 2022. INTERVENTIONS: Quality improvement program implementation began in 2010. MAIN OUTCOMES AND MEASURES: Blood pressure control (systolic BP <140 mm Hg and diastolic BP <90 mm Hg) was assessed using the last outpatient BP measurement in each calendar year. Changes in BP control between Black and White patients from before (2008-2009) to after (2016-2019) implementation of the QI program were examined using a difference-in-difference analysis. Blood pressure control disparities from 2008 through 2019 by age, sex, race and ethnicity, and factors associated with BP control were examined. RESULTS: The number of patients with hypertension increased from 624 094 in 2008 (mean [SD] age, 61.8 [13.5] years; 330 551 [53.0%] female patients; 89 407 [14.3%] Black and 284 116 [45.5%] White patients) to 855 257 in 2019 (mean [SD] age, 64.5 [13.6] years; 444 422 [52.0%] female patients; 107 054 [12.5%] Black and 331 932 [38.8%] White patients). Blood pressure control increased an absolute 4.6% (95% CI, 4.3%-4.8%) among Black patients and 2.1% (95% CI, 2.0%-2.2%) among White patients from before to after the QI program implementation (difference-in-difference: 2.5%; 95% CI, 2.2%-2.8%). The largest reduction in BP control disparity between Black and White female patients was for those aged 50 to 64 years (difference-in-difference: 3.8%; 95% CI, 3.2%-4.4%) and for those aged 18 to 49 years between Black and White male patients (difference-in-difference: 4.2%; 95% CI, 3.0%-5.5%). The proportion of BP control among Black male patients aged 18 to 49 years was the lowest throughout 2008-2019 compared with male and female patients in other age and racial and ethnic groups. In 2019, uncontrolled BP was more common among Black vs White patients (prevalence ratio: 1.13; 95% CI, 1.12-1.14). CONCLUSIONS AND RELEVANCE: This QI program noted that disparities in BP control between Black and White patients were decreased but not eliminated following implementation of QI strategies aimed at reducing disparities in BP control. These findings suggest that more focused interventions may be needed to increase BP control among Black individuals.