Dataset Information

Association of the Mandatory Medicare Bundled Payment With Joint Replacement Outcomes in Hospitals With Disadvantaged Patients.

ABSTRACT:

Importance

Medicare's Comprehensive Care for Joint Replacement (CJR) model rewards or penalizes hospitals on the basis of meeting spending benchmarks that do not account for patients' preexisting social and medical complexity or high expenses associated with serving disadvantaged populations such as dual-eligible patients (ie, those enrolled in both Medicare and Medicaid). The CJR model may have different implications for hospitals serving a high percentage of dual-eligible patients (termed high-dual) and hospitals serving a low percentage of dual-eligible patients (termed low-dual).

Objective

To examine changes associated with the CJR model among high-dual or low-dual hospitals in 2016 to 2017.

Design, setting, and participants

This cohort study comprised 3 analyses of high-dual or low-dual hospitals (n = 1165) serving patients with hip or knee joint replacements (n = 768 224) in 67 treatment metropolitan statistical areas (MSAs) selected for CJR participation and 103 control MSAs. The study used Medicare claims data and public reports from 2012 to 2017. Data analysis was conducted from February 1, 2019, to August 31, 2019.

Exposures

The CJR model holds participating hospitals accountable for the spending and quality of care during care episodes for patients with hip or knee joint replacement, including hospitalization and 90 days after discharge.

Main outcomes and measures

The primary outcomes were total episode spending, discharge to institutional postacute care facility, and readmission within the 90-day postdischarge period; bonus and penalty payments for each hospital; and reductions in per-episode spending required to receive a bonus for each hospital.

Results

In total, 1165 hospitals (291 high-dual and 874 low-dual) and 768 224 patients with joint replacement (494 013 women [64.3%]; mean [SD] age, 76 [7] years) were included. An episode-level triple-difference analysis indicated that total spending under the CJR model decreased at high-dual hospitals (by $851; 95% CI, -$1556 to -$146; P = .02) and low-dual hospitals (by $567; 95% CI, -$933 to -$202; P = .003). The size of decreases did not differ between the 2 groups (difference, -$284; 95% CI, -$981 to $413; P = .42). Discharge to institutional postacute care settings and readmission did not change among both hospital groups. High-dual hospitals were less likely to receive a bonus compared with low-dual hospitals (40.3% vs 59.1% in 2016; 56.9% vs 76.0% in 2017). To receive a bonus, high-dual hospitals would be required to reduce spending by $887 to $2231 per episode, compared with only $89 to $215 for low-dual hospitals.

Conclusions and relevance

The study found that high- and low-dual hospitals made changes in care after CJR implementation, and the magnitude of these changes did not differ between the 2 groups. However, high-dual hospitals were less likely to receive a bonus for spending cuts. Spending benchmarks for CJR would require high-dual hospitals to reduce spending more substantially to receive a financial incentive.

SUBMITTER: Kim H

PROVIDER: S-EPMC6865278 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:ImportanceThere are marked racial/ethnic differences in hip and knee joint replacement care as well as concerns that value-based payments may exacerbate existing racial/ethnic disparities in care.ObjectiveTo examine changes in joint replacement care associated with Medicare's Comprehensive Care for Joint Replacement (CJR) model among White, Black, and Hispanic patients.Design, setting, and participantsRetrospective cohort study of Medicare claims from 2013 through 2017 among White, Black, and Hispanic patients undergoing joint replacement in 67 treatment (selected for CJR participation) and 103 control metropolitan statistical areas.ExposuresThe CJR model holds hospitals accountable for spending and quality of joint replacement care during care episodes (index hospitalization through 90 days after discharge).Main outcomes and measuresThe primary outcomes were spending, discharge to institutional postacute care, and readmission during care episodes.ResultsAmong 688 346 patients, 442 163 (64.2%) were women, and 87 286 (12.7%) were 85 years or older. Under CJR, spending decreased by $439 for White patients (95% CI, -$718 to -$161; from pre-CJR spending in treatment metropolitan statistical areas of $25 264) but did not change for Black patients and Hispanic patients. Discharges to institutional postacute care decreased for all groups (-2.5 percentage points; 95% CI, -4.7 to -0.4, from pre-CJR risk of 46.2% for White patients; -6.0 percentage points; 95% CI, -9.8 to -2.2, from pre-CJR risk of 59.5% for Black patients; and -4.3 percentage points; 95% CI, -7.6 to -1.0, from pre-CJR risk of 54.3% for Hispanic patients). Readmission risk decreased for Black patients by 3.1 percentage points (95% CI, -5.9 to -0.4, from pre-CJR risk of 21.8%) and did not change for White patients and Hispanic patients. Under CJR, Black-White differences in discharges to institutional postacute care decreased by 3.4 percentage points (95% CI, -6.4 to -0.5, from the pre-CJR Black-White difference of 13.3 percentage points). No evidence was found demonstrating that Black-White differences changed for other outcomes or that Hispanic-White differences changed for any outcomes under CJR.Conclusions and relevanceIn this cohort study of patients receiving joint replacements, CJR was associated with decreased readmissions for Black patients. Furthermore, Black patients experienced a greater decrease in discharges to institutional postacute care relative to White patients, representing relative improvements despite concerns that value-based payment models may exacerbate existing disparities. Nonetheless, differences between White and Black patients in joint replacement care still persisted even after these changes.

Project description:ImportanceMedicare beneficiaries with Alzheimer disease and related dementias (ADRD) are a particularly vulnerable group in whom arthritis is a frequently occurring comorbidity. Medicare's mandatory bundled payment reform-the Comprehensive Care for Joint Replacement (CJR) model-was intended to improve quality and reduce spending in beneficiaries undergoing joint replacement surgical procedures for arthritis. In the absence of adjustment for clinical risk, hospitals may avoid performing elective joint replacements for beneficiaries with ADRD.ObjectiveTo evaluate the association of the CJR model with utilization of joint replacements for Medicare beneficiaries with ADRD.Design setting and participantsThis cohort study used national Medicare data from 2013 to 2017 and multivariable linear probability models and a triple differences estimation approach. Medicare beneficiaries with a diagnosis of arthritis were identified from 67 metropolitan statistical areas (MSAs) mandated to participate in CJR and 104 control MSAs. Data were analyzed from July 2020 to July 2021.ExposuresImplementation of the CJR model in 2016.Main outcomes and measuresOutcomes were separate binary indicators for whether or not a beneficiary underwent hip or knee replacement. Key independent variables were the MSA group, before-CJR and after-CJR phase, ADRD diagnosis, and their interactions. The linear probability models controlled for beneficiary characteristics, MSA fixed effects, and time trends.ResultsThe study included 24 598 729 beneficiary-year observations for 9 624 461 unique beneficiaries, of which 250 168 beneficiaries underwent hip and 474 751 underwent knee replacements. The mean (SD) age of the 2013 cohort was 77.1 (7.9) years, 3 110 922 (66.4%) were women, 3 928 432 (83.8%) were non-Hispanic White, 792 707 (16.9%) were dually eligible for Medicaid, and 885 432 (18.9%) had an ADRD diagnosis. Before CJR implementation, joint replacement rates were lower among beneficiaries with ADRD (hip replacements: 0.38% vs 1.17% for beneficiaries with and without ADRD, respectively; P < .001; knee replacements: 0.70% vs 2.25%; P < .001). After controlling for relevant covariates, CJR was associated with a 0.07-percentage-point decline in hip replacements for beneficiaries with ADRD (95% CI, -0.13 to -0.001; P = .046) and a 0.07-percentage-point decline for beneficiaries without ADRD (95% CI, -0.12 to -0.02; P = .01) residing in CJR MSAs compared with beneficiaries in control MSAs. However, this change in hip replacement rates for beneficiaries with ADRD was not statistically significantly different from the change for beneficiaries without ADRD (percentage point difference: 0.01; 95% CI, -0.08 to 0.09; P = .88). No statistically significant changes in knee replacement rates were noted for beneficiaries with ADRD compared with those without ADRD with CJR implementation (percentage point difference: -0.03, 95% CI, -0.09 to 0.02; P = .27).Conclusions and relevanceIn this cohort study of Medicare beneficiaries with arthritis, the CJR model was not associated with a decline in joint replacement utilization among beneficiaries with ADRD compared with beneficiaries without ADRD in the first 2 years of the program, thereby alleviating patient selection concerns.

Project description:BackgroundTo improve the value and efficiency of care among traditional Medicare enrollees, the Centers for Medicare & Medicaid Services has implemented alternative payment models designed to control health-care spending and improve quality. These models may affect care beyond traditional Medicare enrollees, "spilling over" into other populations. Established in April 2016, the Medicare mandatory bundled payment program, called the Comprehensive Care for Joint Replacement (CJR) model, holds hospitals accountable for spending and quality of care for traditional Medicare joint-replacement patients during care episodes that span from the index hospitalization to 90 days post-discharge. We assessed the extent to which the CJR model was associated with outcomes for patients enrolled in commercial insurance and Medicare Advantage plans.MethodsWith use of Health Care Cost Institute claims data from 2012 through 2017, we assessed the association of the CJR model with total expenditures, discharges to institutional post-acute care, and readmissions among commercial insurance and Medicare Advantage joint-replacement patients. The exposure variable was the implementation of the CJR model in 67 randomly selected metropolitan statistical areas compared with 103 similar areas without CJR implementation. We utilized difference-in-differences models to estimate the spillover effects of the CJR model by comparing outcomes between these areas before and after CJR implementation.ResultsThe study included 174,893 joint-replacement episodes of care in commercial insurance enrollees and 202,070 episodes in Medicare Advantage enrollees. Among both commercial insurance and Medicare Advantage enrollees, CJR implementation was associated with no meaningful changes in total episode expenditures, discharges to institutional post-acute care, or readmissions.ConclusionsWe found no evidence for spillover effects of the CJR model on commercial insurance and Medicare Advantage patients, suggesting that alternative payment models targeting traditional Medicare patients may have limited effects on the cost and quality of care for patients outside of the traditional Medicare system.

Project description:BackgroundWe examined whether the Comprehensive Care for Joint Replacement (CJR) model was associated with changes in the receipt of joint replacement among people with Alzheimer's disease and related dementias (ADRD) as well as spending, health service use, and postsurgical outcomes among people with ADRD who underwent a joint replacement surgery.MethodsRetrospective cohort study using 2013-2017 Medicare claims and Minimum Data Set. We used a difference-in-differences analysis to compare people with ADRD residing in CJR-participating treatment areas versus nonparticipating control areas on the receipt of joint replacement, episode spending during the index hospitalization and subsequent 90-day post-discharge period, discharges to an institutional post-acute care setting, and readmissions within 90 days of hospital discharge.ResultsOur sample included 3,361,950 Medicare enrollees with ADRD (2,156,995 women [64%]; mean [SD] age, 83 [8.0] years; 2,646,405 white [78%], 344,478 black [10%], 224,010 Hispanic [7%]). The receipt of replacement among people with ADRD changed similarly between CJR-participating treatment and control areas after CJR model was implemented, suggesting no association of CJR model with the receipt of replacement. Among people with ADRD who received joint replacement, the CJR model was associated with a $1029 decrease in spending per episode (95% confidence interval [CI] -$1577, -$481, p < 0.001), a 1.62 percentage point decrease in discharges to an institutional post-acute care setting (95% CI -3.17, -0.07, p = 0.04), but no changes in 90-day readmission (95% CI -2.68, 0.00, p = 0.051).ConclusionsDespite concerns that the CJR model could hinder people with ADRD from receiving joint replacement, the receipt of joint replacement did not change among people with ADRD under CJR. The CJR model was associated with decreased spending for people with ADRD who received joint replacements, driven by reduced discharges to an institutional post-acute care setting, without any changes in 90-day readmission.

Project description:ImportanceMuch of the evidence for bundled payments has been drawn from models in the traditional Medicare program. Although private insurers are increasingly offering bundled payment programs, it is not known whether they are associated with changes in episode spending and quality.ObjectiveTo evaluate whether a voluntary bundled payment program offered by a national Medicare Advantage insurer was associated with changes in episode spending or quality of care for beneficiaries receiving lower extremity joint replacement (LEJR) surgery.Design, setting, and participantsCross-sectional study of 23 034 LEJR surgical episodes that emulated a stepped-wedge design by using the time-varying, geographically staggered rollout of the bundled payment program from January 1, 2012, to September 30, 2019. Episode-level multivariable regression models were estimated within practice to compare changes before and after program participation, using episodes at physician practices that had not yet begun participating in the program during a given time period (but would go on to do so) as the control. Data analyses were performed from July 1, 2021, to June 30, 2022.ExposuresPhysician practice participation in the bundled payment program.Main outcomes and measuresThe primary outcome was episode spending (plan and beneficiary). Secondary outcomes included postacute care use (skilled nursing facility and home health care), surgical setting (inpatient vs outpatient), and quality (90-day complications [including deep vein thrombosis, wound infection, fracture, or dislocation] and readmissions).ResultsThe final analytic sample included 23 034 LEJR episodes (6355 bundled episodes and 16 679 control episodes) from 109 physician practices participating in the program. Of the beneficiaries, 7730 were male and 15 304 were female, 3057 were Black, 19 351 were White, 447 were of other race or ethnicity (assessed according to the Centers for Medicare & Medicaid Services beneficiary race and ethnicity code, which reflects data reported to the Social Security Administration), and 179 were of unknown race and ethnicity. The mean (SD) age was 70.9 (7.2) years. Participation in the bundled payment program was associated with a 2.7% (95% CI, 1.3%-4.1%) decrease in spending per episode (mean episodic spending, $21 964 [95% CI, $21 636-$22 296] vs $22 562 [95% CI, $22 346-$22 779]), as well as reductions in skilled nursing facility use after discharge (21.3% for bundled episodes vs 25.0% for control episodes; odds ratio [OR], 0.81 [95% CI, 0.67-0.98]) and increased use of the outpatient surgical setting (14.1% for bundled episodes vs 8.4% for control episodes; OR, 1.79 [95% CI, 1.53-2.09]). The program was not associated with changes in quality outcomes, including 90-day complications (8.8% for bundled episodes vs 8.6% for control episodes; OR, 1.02 [95% CI, 0.86-1.20]) and readmissions (4.3% for bundled episodes vs 4.6% for control episodes; OR, 0.92 [95% CI, 0.75-1.13]).Conclusions and relevanceIn this study of an LEJR bundled payment program offered by a national Medicare Advantage insurer, findings suggest that physician practice participation in the program was associated with a decrease in episode spending without changes in quality. Bundled payments offered by private insurers, including Medicare Advantage plans, are an alternate payment option to fee for service that may reduce spending for LEJR episodes while maintaining quality of care.

Project description:ImportanceThe Medicare comprehensive care for joint replacement (CJR) model, a mandatory bundled payment program started in April 2016 for hospitals in randomly selected metropolitan statistical areas (MSAs), may help reduce postacute care (PAC) use and episode costs, but its impact on disparities between Medicaid and non-Medicaid beneficiaries is unknown.ObjectiveTo determine effects of the CJR program on differences (or disparities) in PAC use and outcomes by Medicare-Medicaid dual eligibility status.Design, setting, and participantsObservational cohort study of 2013-2017, based on difference-in-differences (DID) analyses on Medicare data for 1,239,452 Medicare-only patients, 57,452 dual eligibles with full Medicaid benefits, and 50,189 dual eligibles with partial Medicaid benefits who underwent hip or knee surgery in hospitals of 75 CJR MSAs and 121 control MSAs.Main outcome measuresRisk-adjusted differences in rates of institutional PAC [skilled nursing facility (SNF), inpatient rehabilitation, or long-term hospital care] use and readmissions; and for the subgroup of patients discharged to SNF, risk-adjusted differences in SNF length of stay, payments, and quality measured by star ratings, rate of successful discharge to community, and rate of transition to long-stay nursing home resident.ResultsThe CJR program was associated with reduced institutional PAC use and readmissions for patients in all 3 groups. For example, it was associated with reductions in 90-day readmission rate by 1.8 percentage point [DID estimate=-1.8; 95% confidence interval (CI), -2.6 to -0.9; P<0.001] for Medicare-only patients, by 1.6 percentage points (DID estimate=-1.6; 95% CI, -3.1 to -0.1; P=0.04) for full-benefit dual eligibles, and by 2.0 percentage points (DID estimate=-2.0; 95% CI, -3.6 to -0.4; P=0.01) for partial-benefit dual eligibles. These CJR-associated effects did not differ between dual eligibles (differences in above DID estimates=0.2; 95% CI, -1.4 to 1.7; P=0.81 for full-benefit patients; and -0.3; 95% CI, -1.9 to 1.3; P=0.74 for partial-benefit patients) and Medicare-only patients. Among patients discharged to SNF, the CJR program showed no effect on successful community discharge, transition to long-term care, or their persistent disparities.ConclusionsThe CJR program did not help reduce persistent disparities in readmissions or SNF-specific outcomes related to Medicare-Medicaid dual eligibility, likely due to its lack of financial incentives for reduced disparities and improved SNF outcomes.

Project description:Importance:In 2016, the Centers for Medicare & Medicaid Services introduced mandatory bundled payments for knee and hip replacement surgical procedures among traditional Medicare (TM) patients in randomly selected areas. The association of bundled payments with outcomes among patients enrolled in Medicare Advantage (MA) is not known. Objective:To determine the association of bundled payments for joint replacement surgical procedures with the use of postacute care (PAC) services among MA patients. Design, Setting, and Participants:This cohort study used difference-in-differences analysis to evaluate changes in PAC use among patients enrolled in Medicare who underwent joint replacement operations before and after the introduction of bundled payments (ie, from January 1, 2013, to September 30, 2017). A total of 75 metropolitan statistical areas were randomized to participate in the bundled payment program, with 121 areas serving as controls. Data were analyzed between September 15, 2018, and October 1, 2019. Exposure:Bundled payments for hip and knee joint replacement operations, in which hospitals received a single payment to cover all costs associated with a joint replacement and associated care for the 90 days after surgery. Main Outcomes and Measures:The primary outcomes were discharge to any institutional PAC setting and days spent in institutional PAC within 90 days after surgery. Secondary outcomes included discharge and days spent in specific PAC settings (ie, home health, skilled nursing facility, inpatient rehabilitation). Results:Of 1 536 387 individuals who underwent hip and knee join replacement surgery, 493 977 (32.2%) were enrolled in MA (mean [SD] age, 73.3 [8.4] years; 386 699 [63.5%] women; 55 078 [6.4%] black) and 1 042 410 (67.8%) were enrolled in TM (mean [SD] age, 73.3 [8.7] years, 829 014 [65.2%] women; 82 890 [9.4%] black). Among MA patients, bundled payments were associated with a reduction of 1.5 (95% CI, 1.0-2.0) percentage points in discharge to an institutional PAC setting (P < .001) and an estimated reduction of 0.3 (95% CI, 0.2-0.5) days spent in an institutional PAC setting (P < .001), a 5.6% relative reduction. Among TM patients, bundled payments were associated with a reduction of 2.6 (95% CI, 2.2-2.9) percentage points in institutional PAC discharge (P < .001) and a reduction of 0.8 (95% CI, 0.7-0.9) days spent in an institutional PAC setting (P < .001), a 2.5% relative reduction. These changes were larger in hospitals with greater proportions of TM patients. In hospitals with low concentrations of MA patients, time spent in institutional PAC settings decreased by 0.9 days among TM patients and 0.8 days among MA patients; in hospitals with high MA concentrations, time spent in institutional PAC settings decreased by 0.6 days for TM patients and 0.2 days for MA patients. Conclusions and Relevance:In this study, the first 18 months of the Centers for Medicare & Medicaid Services bundled payment program for joint replacement surgery were associated with reductions in the use of institutional PAC among MA patients. Past evaluations of bundled payments that focused on TM patients may not have measured the full consequences of this alternative payment model.

Project description:ImportanceThe Comprehensive Care for Joint Replacement (CJR) model was designed to reduce the cost and improve the quality of hip or knee replacement among Medicare beneficiaries. Yet whether this model may exacerbate existing racial/ethnic disparities in access to the surgery is unclear.ObjectiveTo examine the association of the CJR model with the receipt of elective hip or knee replacement across White, Black, and Hispanic Medicare beneficiaries.Design, setting, and participantsRetrospective cohort study of Medicare claims from 2013 through 2017 among White, Black, and Hispanic Medicare beneficiaries undergoing elective joint replacement in 65 treatment (selected for CJR participation) and 101 control metropolitan statistical areas (MSAs).ExposuresStarting in April 2016, hospitals in the treatment MSAs were required to participate in the CJR model and were accountable for expenditures occurring during patients' hospitalization for hip or knee replacement and 90 days after the hospital discharge.Main outcomes and measuresBeneficiary-level elective hip or knee replacement receipt in a given year.ResultsAmong 17 243 304 patients, 9 839 996 (57%) were women; 2 107 425 (12%) were age 85 years or older. Of the final sample, 14 632 434 (85%) were White beneficiaries, 1 518 629 (9%) were Black beneficiaries, and 1 092 241 (6%) were Hispanic beneficiaries. The CJR model was associated with an increase of 1.6 elective hip or knee replacements per 1000 beneficiary-years for Hispanic beneficiaries (95% CI, 0.06-2.05) and a decrease of 0.64 replacements for Black beneficiaries (95% CI, -1.25 to -0.02). No evidence was found for any changes for White beneficiaries per 1000 beneficiary-years (0.04 replacements, 95% CI, -0.35 to 0.42 replacements). The Black-White difference in the rate of elective hip or knee replacement per 1000 beneficiary-years further widened by 0.68 replacements (-0.68, 95% CI, -1.20 to -0.15).Conclusions and relevanceIn this cohort study, the CJR model was associated with increased receipt of elective hip or knee replacement among Hispanic beneficiaries, decreased receipt among Black beneficiaries, and no change in receipt among White beneficiaries. The decreased receipt of elective hip or knee replacement among Black beneficiaries may suggest that value-based payment models, including the CJR model, could be monitored for unintended consequences. However, the lack of similar findings among Hispanic beneficiaries suggests that payment models may have differential impacts across racial/ethnic groups.

Project description:ImportanceMedicare's Bundled Payments for Care Improvement (BPCI) initiative for lower extremity joint replacement (LEJR) surgery has been associated with a reduction in episode spending and stable-to-improved quality. However, BPCI may create unintended effects by prompting participating hospitals to increase the overall volume of episodes paid for by Medicare, which could potentially eliminate program-related savings or prompt them to shift case mix to lower-risk patients.ObjectiveTo evaluate whether hospital BPCI participation for LEJR was associated with changes in overall volume and case mix.Design, setting, and participantsObservational study using Medicare claims data and a difference-in-differences method to compare 131 markets (hospital referral regions) with at least 1 BPCI participant hospital (n = 322) and 175 markets with no participating hospitals (n = 1340), accounting for 580 043 Medicare beneficiaries treated before (January 2011-September 2013) and 462 161 after (October 2013-December 2015) establishing the BPCI initiative. Hospital-level case-mix changes were assessed by comparing 265 participating hospitals with a 1:1 propensity-matched set of nonparticipating hospitals from non-BPCI markets.ExposuresHospital BPCI participation.Main outcomes and measuresChanges in market-level LEJR volume in the before vs after BPCI periods and changes in hospital-level case mix based on demographic, socioeconomic, clinical, and utilization factors.ResultsAmong the 1 717 243 Medicare beneficiaries who underwent LEJR (mean age, 75 years; 64% women; and 95% nonblack race/ethnicity), BPCI participation was not significantly associated with a change in overall market-level volume. The mean quarterly market volume in non-BPCI markets increased 3.8% from 3.8 episodes per 1000 beneficiaries before BPCI to 3.9 episodes per 1000 beneficiaries after BPCI was launched. For BPCI markets, the mean quarterly market volume increased 4.4% from 3.6 episodes per 1000 beneficiaries before BPCI to 3.8 episodes per 1000 beneficiaries after BPCI was launched. The adjusted difference-in-differences estimate between the market types was 0.32% (95% CI, -0.06% to 0.69%; P = .10). Among 20 demographic, socioeconomic, clinical, and utilization factors, BPCI participation was associated with differential changes in hospital-level case mix for only 1 factor, prior skilled nursing facility use (adjusted difference-in-differences estimate, -0.53%; 95% CI, -0.96% to -0.10%; P = .01) in BPCI vs non-BPCI markets.Conclusions and relevanceIn this observational study of Medicare beneficiaries who underwent LEJR, hospital participation in Bundled Payments for Care Improvement was not associated with changes in market-level lower extremity joint replacement volume and largely was not associated with changes in hospital case mix. These findings may provide reassurance regarding 2 potential unintended effects associated with bundled payments for LEJR.

Project description:BACKGROUND:In 2016, Medicare implemented Comprehensive Care for Joint Replacement (CJR), a national mandatory bundled-payment model for hip or knee replacement in randomly selected metropolitan statistical areas. Hospitals in such areas receive bonuses or pay penalties based on Medicare spending per hip- or knee-replacement episode (defined as the hospitalization plus 90 days after discharge). METHODS:We conducted difference-in-differences analyses using Medicare claims from 2015 through 2017, encompassing the first 2 years of bundled payments in the CJR program. We evaluated hip- or knee-replacement episodes in 75 metropolitan statistical areas randomly assigned to mandatory participation in the CJR program (bundled-payment metropolitan statistical areas, hereafter referred to as "treatment" areas) as compared with those in 121 control areas, before and after implementation of the CJR model. The primary outcomes were institutional spending per hip- or knee-replacement episode (i.e., Medicare payments to institutions, primarily to hospitals and post-acute care facilities), rates of postsurgical complications, and the percentage of "high-risk" patients (i.e., patients for whom there was an elevated risk of spending - a measure of patient selection). Analyses were adjusted for the hospital and characteristics of the patients and procedures. RESULTS:From 2015 through 2017, there were 280,161 hip- or knee-replacement procedures in 803 hospitals in treatment areas and 377,278 procedures in 962 hospitals in control areas. After the initiation of the CJR model, there were greater decreases in institutional spending per joint-replacement episode in treatment areas than in control areas (differential change [i.e., the between-group difference in the change from the period before the CJR model], -$812, or a -3.1% differential decrease relative to the treatment-group baseline; P<0.001). The differential reduction was driven largely by a 5.9% relative decrease in the percentage of episodes in which patients were discharged to post-acute care facilities. The CJR program did not have a significant differential effect on the composite rate of complications (P=0.67) or on the percentage of joint-replacement procedures performed in high-risk patients (P=0.81). CONCLUSIONS:In the first 2 years of the CJR program, there was a modest reduction in spending per hip- or knee-replacement episode, without an increase in rates of complications. (Funded by the Commonwealth Fund and the National Institute on Aging of the National Institutes of Health.).