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

Abstract

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.

Figure 1.. Association Between Process Measures and MIPS Scores

Plots present the unadjusted primary care physician process measure performance by Medicare Merit-based Incentive Payment System (MIPS) categories. Upper and lower boundaries of boxes indicate 25th and 75th percentiles; whiskers, 10th and 90th percentiles; horizontal lines within the boxes, 50th percentile (median); and diamonds, mean. MIPS categories were defined as low (≤30), medium (>30-75), and high (>75), which aligns with MIPS program thresholds for payment adjustments (physicians with scores <30 received penalties and those with a score of 30 received no adjustment, while those with scores >30-75 received positive adjustments and those with scores >75 were eligible for an “exceptional performance” bonus). Ns listed below each MIPS category indicate the number of physicians included in the plot. The 90th, 75th, and 50th percentiles were 100% for influenza immunization and the 90th through 25th percentiles were 100% for tobacco screening, suggesting that these measures were “topped out.”

Figure 2.. Association Between Adjusted Clinical Outcome Measures and MIPS Scores

Plots present the adjusted physician clinical outcome measure performance by Medicare Merit-based Incentive Payment System (MIPS) categories. Upper and lower boundaries of boxes indicate 25th and 75th percentiles; whiskers, 10th and 90th percentiles; horizontal lines within the boxes, 50th percentile (median); and diamonds, mean. For each physician, outcome measure performance was defined as the number of patients with an ambulatory care–sensitive admission, emergency department visits not resulting in an inpatient admission, and number of all-cause inpatient admissions per 1000 attributed and eligible patients in the year. Adjusted clinical outcome represents the expected rate for a physician had the physician treated the average case-mix of patients. Adjustment based on patient-level logistic regression adjusting for enrollee age, sex, Hierarchical Condition Category risk score, and Hospital Referral Region. Empirical Bayes shrinkage estimator applied to account for the variation in a physician’s panel size (see eMethods in Supplement 1). MIPS categories defined as low (≤30), medium (>30-75), and high (>75), which aligns with MIPS program thresholds for payment adjustments (physicians with scores <30 received penalties and those with a score of 30 received no adjustment, while those with scores >30-75 received positive adjustments and those with scores >75 were eligible for an “exceptional performance” bonus). Details on outcome definitions are available in eTable 1 in Supplement 1. Ns listed below each MIPS category indicate the number of physicians included in the plot.

Figure 3.. Distribution of Adjusted Clinical Outcome Quintiles by MIPS Score Categories

Medicare Merit-based Incentive Payment System (MIPS) score categories align with MIPS program thresholds for payment adjustments (physicians with scores <30 received penalties and those with a score of 30 received no adjustment, while those with scores >30-75 received positive adjustments and those with scores >75 were eligible for an “exceptional performance” bonus). Composite outcome defined as the weighted average of physicians’ observed-to-expected outcomes across 6 measures (4 ambulatory care–sensitive measures, emergency department visits not resulting in an inpatient admission, and number of all-cause inpatient admissions) for which weights were the inverse standard deviation of the measure. Observed-to-expected outcomes constructed using patient-level logistic regression adjusted for patient age, sex, Hierarchical Condition Category quintile, and hospital referral region (details available in the eMethods in Supplement 1).