Association Between Individual Primary Care Physician Merit-based Incentive Payment System Score and Measures of Process and Patient Outcomes.

Importance: The Medicare Merit-based Incentive Payment System (MIPS) influences reimbursement for hundreds of thousands of US physicians, but little is known about whether program performance accurately captures the quality of care they provide. Objective: To examine whether primary care physicians' MIPS scores are associated with performance on process and outcome measures. Design, Setting, and Participants: Cross-sectional study of 80 246 US primary care physicians participating in the MIPS program in 2019. Exposures: MIPS score. Main Outcomes and Measures: The association between physician MIPS scores and performance on 5 unadjusted process measures, 6 adjusted outcome measures, and a composite outcome measure. Results: The study population included 3.4 million patients attributed to 80 246 primary care physicians, including 4773 physicians with low MIPS scores (≤30), 6151 physicians with medium MIPS scores (>30-75), and 69 322 physicians with high MIPS scores (>75). Compared with physicians with high MIPS scores, physicians with low MIPS scores had significantly worse mean performance on 3 of 5 process measures: diabetic eye examinations (56.1% vs 63.2%; difference, -7.1 percentage points [95% CI, -8.0 to -6.2]; P < .001), diabetic HbA1c screening (84.6% vs 89.4%; difference, -4.8 percentage points [95% CI, -5.4 to -4.2]; P < .001), and mammography screening (58.2% vs 70.4%; difference, -12.2 percentage points [95% CI, -13.1 to -11.4]; P < .001) but significantly better mean performance on rates of influenza vaccination (78.0% vs 76.8%; difference, 1.2 percentage points [95% CI, 0.0 to 2.5]; P = .045] and tobacco screening (95.0% vs 94.1%; difference, 0.9 percentage points [95% CI, 0.3 to 1.5]; P = .001). MIPS scores were inconsistently associated with risk-adjusted patient outcomes: compared with physicians with high MIPS scores, physicians with low MIPS scores had significantly better mean performance on 1 outcome (307.6 vs 316.4 emergency department visits per 1000 patients; difference, -8.9 [95% CI, -13.7 to -4.1]; P < .001), worse performance on 1 outcome (255.4 vs 225.2 all-cause hospitalizations per 1000 patients; difference, 30.2 [95% CI, 24.8 to 35.7]; P < .001), and did not have significantly different performance on 4 ambulatory care-sensitive admission outcomes. Nineteen percent of physicians with low MIPS scores had composite outcomes performance in the top quintile, while 21% of physicians with high MIPS scores had outcomes in the bottom quintile. Physicians with low MIPS scores but superior outcomes cared for more medically complex and socially vulnerable patients, compared with physicians with low MIPS scores and poor outcomes. Conclusions and Relevance: Among US primary care physicians in 2019, MIPS scores were inconsistently associated with performance on process and outcome measures. These findings suggest that the MIPS program may be ineffective at measuring and incentivizing quality improvement among US physicians.