Influence of hospital volume on revision rate after total knee arthroplasty with cement.
BACKGROUND
The number of total knee replacements has substantially increased worldwide over the past ten years. Several studies have indicated a correlation between high hospital procedure volume and decreased morbidity and mortality following total knee arthroplasty. The purpose of the present study was to evaluate whether there is a correlation between procedure volume and the risk of revision following total knee arthroplasty with use of hospital volume data from the Norwegian Arthroplasty Register.


METHODS
Thirty-seven thousand, three hundred and eighty-one total knee arthroplasties that were reported to the Norwegian Arthroplasty Register from 1994 to 2010 were used to examine the annual procedure volume per hospital. Hospital volume was divided into five categories according to the number of procedures performed annually: one to twenty-four (low volume), twenty-five to forty-nine (medium volume), fifty to ninety-nine (medium volume), 100 to 149 (high volume), and ≥150 (high volume). Cox regression (adjusted for age, sex, and diagnosis) was used to estimate the proportion of procedures without revision and the risk ratio (RR) of revision. Analyses were also performed for two commonly used prosthesis brands combined.


RESULTS
The rate of prosthetic survival at ten years was 92.5% (95% confidence interval, 91.5 to 93.4) for hospitals with an annual volume of one to twenty-four procedures and 95.5% (95% confidence interval, 94.1 to 97.0) for hospitals with an annual volume of ≥150 procedures. We found a significantly lower risk of revision for hospitals with an annual volume of 100 to 149 procedures (relative risk = 0.73 [95% confidence interval, 0.56 to 0.96], p = 0.03) and ≥150 procedures (relative risk = 0.73 [95% confidence interval, 0.54 to 1.00], p = 0.05) compared with hospitals with an annual volume of one to twenty-four procedures. Similar results were found when we analyzed two commonly used prosthesis brands.


CONCLUSIONS
In the present study, there was a significantly higher rate of revision knee arthroplasties at low-volume hospitals as compared with high-volume hospitals.
Kysthospital in Hagavik, Hagaviksbakken 25, 5217 Hagavik, Norway. E-mail address for M. Badawy: mona.badawy@helse-bergen.no. E-mail address for K. Indrekvam: kari.indrekvam@helse-bergen.no.
Mona
M
Badawy
Birgitte
B
Espehaug
Kari
K
Indrekvam
Lars B
LB
Engesæter
Leif I
LI
Havelin
Ove
O
Furnes
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods / Q000706:statistics & numerical data*; D001843:Bone Cements / Q000009:adverse effects*; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D011475:Prosthesis Failure; D012086:Reoperation / Q000706:statistics & numerical data*; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
D001843:Bone Cements