What Is the Association Between Hospital Volume and Complications After Revision Total Joint Arthroplasty: A Large-database Study
Authors: Ricciardi Benjamin F. , Liu Andrew Y. , Qiu Bowen , Myers Thomas G. , Thirukumaran Caroline P. 
Published: April 2019

Abstract

Background
Studies of primary total joint arthroplasty (TJA) show a correlation between hospital volume and outcomes; however, the relationship of volume to outcomes in revision TJA is not well studied.

Questions/purposes
We therefore asked: (1) Are 90-day readmissions more likely at low-volume hospitals relative to high-volume hospitals after revision THA and TKA? (2) Are in-hospital and 90-day complications more likely at low-volume hospitals relative to high-volume hospitals after revision THA and TKA? (3) Are 30-day mortality rates higher at low-volume hospitals relative to high-volume hospitals after revision THA and TKA?

Methods
Using 29,948 inpatient stays undergoing revision TJA from 2008 to 2014 in the Statewide Planning and Research Cooperative System (SPARCS) database for New York State, we examined the relationship of hospital revision volume by quartile and outcomes. The top 5 percentile of hospitals was included as a separate cohort. Advantages of the SPARCS database include comprehensive catchment of all cases regardless of payer, and the ability to track each patient across hospital admissions at different institutions within the state. The outcomes of interest included 90-day all-cause readmission rates and 30- and 90-day reoperation rates, postoperative complication rates, and 30-day mortality rates. The initial cohort that met the MS-DRG and ICD-9 criteria consisted of 30,354 inpatient stays for revision hip or knee replacements. Exclusions included patients with a missing patient identifier (n = 221), missing admission or discharge dates (n = 5), and stays from hospitals that were closed during the study period (n = 180). Our final analytic cohort comprised 29,948 inpatient stays for revision hip and knee replacements from 25,977 patients who had nonmissing data points for the variables of interest. Outcomes were adjusted for underlying hospital, surgeon, and patient confounding variables. The analytic cohort included observations from 25,977 patients, 138 hospitals, 929 surgeons, 14,130 revision THAs, 11,847 revision TKAs, 15,341 female patients (59% of cohort).

Results
Patients had lower all-cause 90-day readmission rates in the highest 5th percentile by volume hospitals relative to all other lower hospital volume categories. Reoperation rates within the first 90 days, however, were not different among volume categories. All-cause 90-day readmissions were higher in the quartile 4 hospitals excluding the top 5th percentile (17%) versus the top 5th percentile by volume hospitals (12%) (odds ratio [OR]: 1.3; 95% confidence interval [CI], 1.0–1.5; p = 0.030). All-cause 90-day readmissions were higher in the quartile 3 hospitals (18%) relative to the top 5 percentile by volume hospitals (12%) (OR: 1.5; 95% CI, 1.2–1.9; p < 0.001). All-cause 90-day readmissions were higher in quartile 2 hospitals (18%) relative to the top 5 percentile by volume hospitals (12%) (OR: 1.4; 95% CI, 1.1–1.8; p = 0.010). All-cause 90-day readmissions were higher in quartile 1 hospitals (21%) versus the top 5 percentile by volume hospitals (12%) (OR: 1.6; 95% CI, 1.1–2.3; p = 0.010). Postoperative complication rates were higher among only the quartile 1 hospitals compared with institutions in each higher-volume category after revision TJA. The odds of 90-day complications compared with quartile 1 hospitals were 0.49 (95% CI, 0.33–0.72; p = 0.010) for quartile 2, 0.60 (95% CI, 0.40–0.88; p = 0.010) for quartile 3, 0.43 (95% CI, 0.28–0.64; p = 0.010) for quartile 4 excluding top 5 percentile, and 0.36 (95% CI, 0.22–0.59; p = 0.010) for the top 5 percentile of hospitals. There does not appear to be an association between 30-day mortality rates and hospital volume in revision TJA. The odds of 30-day mortality compared with quartile 1 hospitals were 0.54 (95% CI, 0.20–1.46; p = 0.220) for quartile 2, 0.75 (95% CI, 0.30–1.91; p = 0.550) for quartile 3, 0.57 (95% CI, 0.22–1.49; p = 0.250) for quartile 4 excluding top 5 percentile, and 0.61 (95% CI, 0.20–1.81; p = 0.370) for the top 5 percentile of hospitals.

Conclusions
These findings suggest that regionalizing revision TJA services, or concentrating surgical procedures in higher-volume hospitals, may reduce early complications rates and 90-day readmission rates. Disadvantages of regionalization include reduced access to care, increased patient travel distances, and possible capacity issues at receiving centers. Further studies are needed to evaluate the benefits and negative consequences of regionalizing revision TJA services to higher-volume revision TJA institutions.

Level of Evidence
Level III, therapeutic study.