All-Patient Refined Diagnosis-Related Groups (APR-DRGs) in Primary Arthroplasty

Pay for performance protocols require that outcomes be adjusted for severity of illness. The APR-DRGs are currently utilized to pay and evaluate hospitals and will eventually be utilized to pay and evaluate surgeons. Our objective was to investigate if this system of severity adjustment is predictive of arthroplasty outcomes. Patients (n = 274) undergoing primary arthroplasty were studied. Outcomes (WOMAC, SF-36, and Quality of Well Being (QWB) were administered before and 24 months following surgery. APR-DRG classification, including severity of illness subclass scores and a risk of mortality were obtained. Charlson, ASA, Charnley, length of stay (LOS), hospital charges, and costs were also extracted. Analyses of variance were used to determine the effect between classification and pre- and post-operative outcomes. P<.05 was considered significant. Average LOS increased with increasing severity of illness [1 = 3.78+.13 (SE) days, 2 = 4.14+.15 days, 3 = 4.87+.26 days, p<0.05]. Severity of illness was also associated in a dose-response fashion with pre-operative but not post-operative QWB (p<0.05) and WOMAC total scores (p<0.05). Mortality subclass scores of 2 were associated with lower preoperative QWB (p<0.05) and SF-36 (p<0.01) Patients in the severe mortality category (34.08+1.40) had worse scores on the WOMAC than group 1 (29.67+1.6, p = 0.041) and group 2 (29.49+.97, p = 0.008). Patients in the more severe mortality category ($5,455+322) had significantly (p = 0.007) greater fixed costs compared to group 1 ($4,560+95). The APR-DRGs classification does not show a strong correlation with patient oriented outcomes in arthroplasty patients. However, it does strongly correlate with hospital finances.