Hospitals that conduct a high volume of surgical procedures and have a low 30-day mortality rate have lower readmission rates, according to a new study. Even so, about one in seven patients discharged after major surgery is readmitted in the first 30 days, the authors found.
The researchers also showed that strictly following surgical process measures – such as infection control techniques – was only weakly associated with reduced readmissions.
The results are not terribly surprising, according to the authors, Dr. Thomas C. Tsai and his colleagues from Harvard University, Brigham and Women’s Hospital, and the Veterans Affairs Boston Healthcare System. The researchers could not specifically determine why the higher-volume, lower-mortality hospitals had lower readmission rates, but they speculated that these facilities have systems in place to protect surgical patients from bad outcomes that might bring them back to the hospital. Their study was published Sept. 18 in the New England Journal of Medicine (2013;369:1134-42).
The Medicare program now penalizes hospitals for excess readmissions after discharge for heart failure, heart attack, and pneumonia. For fiscal year 2013, which ends on Oct. 1, hospitals will be penalized 1% of their total Medicare billings if readmissions are too high. In fiscal 2014, chronic obstructive pulmonary disease and coronary artery bypass grafting will be added to the list of monitored conditions. The penalty rises to 2% in fiscal year 2014 and 3% in fiscal 2015. In coming years, the Centers for Medicare and Medicaid Services is expected to add more surgical procedures to the readmission penalty list.
The researchers analyzed national Medicare data, which comprised 479,471 discharges from 3,004 hospitals. These hospitals accounted for 90% of the discharges for the six major procedures studied: coronary artery bypass grafting, pulmonary lobectomy, endovascular repair of abdominal aortic aneurysm, open repair of AAA, colectomy, and hip replacement. The authors also analyzed Hospital Quality Alliance (HQA) surgical care scores. The HQA score is calculated based on how well hospitals perform on process measures established by the Surgical Care Improvement Project.
The three measures of surgical quality included the HQA score, procedure volume, and 30-day mortality. The primary outcome measure was a hospital-level composite of the six procedure-specific, risk-adjusted readmission rates at 30 days. The authors compared the characteristics of patients who were readmitted within 30 days with those who were not, and compared the characteristics of hospitals that had composite readmission rates above the median with those that had rates below the median.
The median composite risk-adjusted 30-day readmission rate was 13%. Patients who were readmitted tended to be older (78 years vs. 77 years) and had more comorbidities. The hospitals with readmission rates below the median were more likely to be nonprofit, nonteaching, and located in the West. They also had a higher number of full-time nurses per 1,000 patient-days and a lower proportion of Medicaid patients.
There was no significant difference between urban and rural hospitals.
The authors used multivariate models to gauge the impact of quality measures on readmission rates. After accounting for hospital characteristics, they found that hospitals with the highest volume of procedures had a readmission rate just under the median, compared with those with the lowest procedure volumes, which had a readmission rate of close to 17%.
Hospitals in the lowest quartile for mortality rates had a 13% readmission rate, compared with 14% for those in the highest mortality quartile.
Overall, there was no significant difference in readmissions between the hospitals that performed the best on the HQA score and those that were the poorest performers. That might be because there was only a very small variation in performance on the HQA score – with a median of 99% for high performers and 92% for low performers, said the authors.
Policymakers should be reassured by their consistent findings that readmissions are linked to certain quality measures – volume and mortality, the investigators said. But a direct link is still not definitive, said Dr. Tsai and his colleagues. Previous studies have indicated that volume did help reduce readmissions, while others have shown no relationship.
But those studies were conducted before the widespread use of minimally invasive procedures and process measures aimed at reducing postsurgical complications, the authors said.
The authors reported no relevant conflicts of interest.
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