Hospital volume–outcome relationship in total knee arthroplasty: a systematic review and dose–response meta-analysis

PURPOSE: This systematic review and dose–response meta-analysis aimed to investigate the relationship between hospital volume and outcomes for total knee arthroplasty (TKA). METHODS: MEDLINE, Embase, CENTRAL and CINAHL were searched up to February 2020 for randomised controlled trials and cohort studies that reported TKA performed in hospitals with at least two different volumes and any associated patient-relevant outcomes. The adjusted effect estimates (odds ratios, OR) were pooled using a random-effects, linear dose–response meta-analysis. Heterogeneity was quantified using the I(2)-statistic. ROBINS-I and the GRADE approach were used to assess the risk of bias and the confidence in the cumulative evidence, respectively. RESULTS: A total of 68 cohort studies with data from 1985 to 2018 were included. The risk of bias for all outcomes ranged from moderate to critical. Higher hospital volume may be associated with a lower rate of early revision ≤ 12 months (narrative synthesis of k = 7 studies, n = 301,378 patients) and is likely associated with lower mortality ≤ 3 months (OR = 0.91 per additional 50 TKAs/year, 95% confidence interval [0.87–0.95], k = 9, n = 2,638,996, I(2) = 51%) and readmissions ≤ 3 months (OR = 0.98 [0.97–0.99], k = 3, n = 830,381, I(2) = 44%). Hospital volume may not be associated with the rates of deep infections within 1–4 years, late revision (1–10 years) or adverse events ≤ 3 months. The confidence in the cumulative evidence was moderate for mortality and readmission rates; low for early revision rates; and very low for deep infection, late revision and adverse event rates. CONCLUSION: An inverse volume–outcome relationship probably exists for some TKA outcomes, including mortality and readmissions, and may exist for early revisions. Small reductions in unfavourable outcomes may be clinically relevant at the population level, supporting centralisation of TKA to high-volume hospitals. LEVEL OF EVIDENCE: III. REGISTRATION NUMBER: The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO CRD42019131209 available at: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=131209). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00167-021-06692-8.