Blood pressure control rates were significantly higher in summer (75.2%) than winter (73.1%), a 2.1-percentage-point difference (P=0.002), indicating seasonal variation affects quality measurement.
Observational
Yes
Does a rolling Q4 average account for seasonal variation and improve measured blood pressure control rates compared to the HEDIS final-reading method in an ambulatory network?
Seasonal blood pressure variation significantly impacts quality metrics, suggesting that multi-reading or seasonally adjusted methods like a rolling Q4 average provide a more accurate assessment of BP control than a single year-end reading.
Effect estimate: Difference 2.1 percentage points
Absolute Event Rate: 75.2% vs 73.1%
p-value: p=0.002
Blood pressure (BP) control is a core quality metric in value-based care (VBC). The Healthcare Effectiveness Data and Information Set (HEDIS) Controlling High Blood Pressure (CBP) measure uses the final BP reading of the calendar year, a method that overlooks well-documented seasonal variation—BP declines in summer and rises in winter. We evaluated the impact of this pattern on measured performance in a large health system. We conducted a retrospective analysis of monthly BP control rates (July 2019 to December 2025) across the Jefferson Health-Lehigh ambulatory network, totaling 78 months and approximately 7.6 million patient-months. Summer (June to August) and winter (December to February) rates were compared using paired t -tests and ordinary least square regression with seasonal adjustment. Year-end performance was assessed using both the HEDIS final-reading (December rate) and a rolling Q4 average (October to December mean). Standard VBC quality improvement initiatives with Q4 intensification were in place. BP control rates were significantly higher in summer (75.2%; 95% confidence interval CI: 73.5%–77.0%) than winter (73.1%; 95% CI: 71.2%–75.1%), a 2.1-percentage-point difference (paired t = 5.13, P = 0.002). This pattern was consistent across all 7 years. Within-year peak-to-trough amplitude averaged 2.8 percentage points in nonpandemic years. The rolling Q4 average exceeded the December-only rate in all years, with differences of 0.06–0.59 percentage points, reclassifying 60–520 additional patients as controlled annually. Seasonal BP variation is robust and inadequately addressed by current quality measures. Multi-reading or seasonally adjusted methods would improve measurement accuracy and fairness. Engagement with NCQA and CMS to pilot redesigned measures is recommended.
Stephens et al. (Sat,) conducted a observational in High Blood Pressure. Summer season vs. Winter season was evaluated on Blood pressure control rates (Difference 2.1 percentage points, p=0.002). Blood pressure control rates were significantly higher in summer (75.2%) than winter (73.1%), a 2.1-percentage-point difference (P=0.002), indicating seasonal variation affects quality measurement.