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ACO Participation Associated with Improvements in HACs

As the Medicare Shared Savings Program (MSSP) enters its fourth performance year, the growing volume of data has given analysts a better opportunity to assess the initiative’s overall impact on quality and spending. One study published in Health Affairs found that hospitals affiliated with ACOs had better readmission rates from SNFs and more rapid improvement rates than unaffiliated hospitals. Though the authors were unable to identify why ACO-affiliated hospitals outperformed others, they speculated that better communication between providers and effective patient intervention could be important factors. While such practices may help lower readmissions, their effect on other quality metrics is less clear. According to a Definitive Healthcare analysis, hospitals participating in ACOs or with ACO experience show better improvement in hospital-acquired conditions (HAC) scores, but they rank behind hospitals unaffiliated with ACOs or with no or very recent ACO experience in several measures.

Previous studies have shown that ACOs participating in the MSSP tend to improve over time as they get accustomed to the program and adjust their operations to maximize quality and efficiency. One might expect hospitals that joined ACOs early may have superior performance than those that entered the program more recently, but the HAC score data shows no obvious correlation. According to statistics from CMS’ HAC Reduction program, hospitals involved with ACOs in 2010, 2011, and 2012 had worse overall HAC scores for FY 2017 than facilities that joined ACOs in 2013, 2014, 2015. The former group’s scores generally improved over the three-year measurement period, but not at the same rate of those that joined ACOs later, which experienced rapid improvement in SSI Colon/Hysterectomy and total HAC scores. While HAC scores represent a hospital’s relative performance to other facilities rather than an absolute value, the dramatic improvement of the late-joining hospitals suggests they did better in some areas.

Average Hospital HAC Scores - First ACO Involvement 2010-2012
*2016 first reporting year for SSI Colon/Hysterectomy. Source: Definitive Healthcare
Average Hospital HAC Scores, First ACO Involvement 2013-2015
*2016 first reporting year for SSI Colon/Hysterectomy. Source: Definitive Healthcare

If a hospital’s level of experience with ACOs doesn’t correspond to better HAC and VBP scores, does ACO involvement itself make a difference? The data suggests it does. ACO-affiliated hospitals showed improvement in overall HAC scores and several individual metrics, while unaffiliated hospitals’ performance worsened on a relative basis over time. However, the ACO group had much higher scores to begin with, and its ending figures were still not as strong as the non-ACO group.

The ACO group of hospitals made significant gains in the total HAC score, the patient-safety index composite score (PSI 90), and surgical site infection (SSI) rating for colon procedures and hysterectomies. Average scores for central-line-associated blood infections (CLABSI) and catheter-associated urinary tract infections (CAUTI) worsened slightly. The opposite happened for the non-ACO group, which had lower rates of CLABSIs and CAUTIs but worse HAC, SSI, and PSI scores. Given that roughly 36 percent of all short-term acute care and critical-access hospitals have participated in ACOs prior to 2016 and the nature of the HAC scoring system, any improvement in one segment will be reflected in the scores of the others if their performance remains constant. While it’s technically possible that the non-ACO group drove the trend, it’s unlikely because ACO programs put substantial pressure on providers to improve quality and reduce spending and in the case of the MSSP ACOs, have consistently outperformed control groups, according to CMS. Even with the improvement, ACO-affiliated hospitals still have higher relative scores, suggesting that a significant quality difference remains.

Average Hospital HAC Scores - Any ACO Involvement 2010-2015
*2016 first reporting year for SSI Colon/Hysterectomy. Source: Definitive Healthcare
Average Hospital HAC Scores - No ACO Involvment 2010-2015
*2016 first reporting year for SSI Colon/Hysterectomy. Source: Definitive Healthcare

It’s important to note that while the ACO group has higher overall scores, it also has a higher average case mix, 1.48 compared to 1.33. CMS does not adjust HAC scoring for case mix, stating that each of the patient events are so serious that they should not happen to anyone, regardless of existing conditions, morbidity, or risk factors. However, at least one study has found a strong correlation with HAC scores and several hospital characteristics, including case mix. It’s likely that many of the hospitals decided to participate in ACOs specifically because they had a greater need to address spending and quality for their patients, which also translated into greater potential savings. While the change is gradual, it seems clear that expanding a hospital’s ACO involvement, or at least applying accountable care practices to the general population, is associated with better quality outcomes.

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