The relationship between the American Society Of Anesthesiologists physical rating and outcome following total hip and knee arthroplasty: an analysis of theNew Zealand Joint Registry.

BACKGROUND: The purpose of this study was to review the results of the first four years of use of the American Society of Anesthesiologists (ASA) physical status rating system in the New Zealand Joint Registry. Our hypothesis was that patients with a higher ASA score would have an increased mortality rate, an increased early revision arthroplasty rate, and poorer clinical outcomes at six months after total hip or knee arthroplasty. METHODS: We prospectively evaluated the preoperative ASA classes for all patients in the registry who underwent primary total hip or knee arthroplasty from 2005 to 2008 with regard to the six-month mortality rate and the Oxford Hip and Knee Scores at six months. Survival curves were constructed with use of revision joint replacement as the end point. RESULTS: Twenty-two thousand six hundred patients who underwent total hip arthroplasties and 18,434 patients who underwent total knee arthroplasties were recorded in the New Zealand Joint Registry. The six-month mortality rate was 0.77% following hip arthroplasty and 0.40% following knee arthroplasty. Significant differences were observed in the mortality rate between all ASA classes following hip arthroplasty (p < 0.001). Similarly, significant differences were observed in the mortality rate between ASA classes after knee arthroplasty, except between ASA classes 1 and 2 and between ASA classes 3 and 4. The mortality rate was significantly higher (p < 0.001) following hip arthroplasty compared with knee arthroplasty. A significant difference (p < 0.001) in Oxford scores was observed when ASA class 1 and ASA class 2 were compared with ASA class 3 and ASA class 4, independent of age and sex, following both hip or knee arthroplasty. A significant difference was observed in the rate of early revision (revision less than two years after the index procedure) following total hip arthroplasty when ASA class 1 (hazard ratio, 1.39 [95% confidence interval (CI), 1.04 to 1.95]; p = 0.015) and ASA class 2 (hazard ratio, 1.24 [95% CI, 1.02 to 1.55]; p = 0.030) were compared with ASA class 3, which was independent of age and sex. No significant difference was observed in the rate of early revision after total knee arthroplasty. CONCLUSIONS: The ASA physical status score can be used as a predictor of postoperative mortality and functional status following both hip and knee arthroplasty and may predict early failure of total hip arthroplasty necessitating revision. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Bilateral total joint arthroplasty: the early results from the New Zealand National Joint Registry.

This study evaluated the mortality rate, major complications, and early outcomes of single anesthetic bilateral total hip and knee arthroplasty compared with unilateral and staged procedures. A total of 37,828 total hip and knee arthroplasties were evaluated with 6-month Oxford 12 scores. Major complications and mortality rates were recorded. Analysis of variance tables were used for statistical analysis. The single anesthetic bilateral group were significantly younger (P < .001), with their age-adjusted postoperative Oxford 12 scores significantly better (P < .001) than the other 2 groups. The surgeons involved, in general, performed more than 25 total knee and hip arthroplasties per year. There was 1 death within the first 6 months occurring in the staged bilateral group and was unrelated to the surgery. The complication rate as reported by patients was low in all groups, and there was no significant difference. The results show that, in selected patients, single anesthetic bilateral total knee or hip arthroplasty is a safe, low-risk procedure with very good patient-generated outcome scores at 6 months when performed by an experienced surgeon.