Is case-mix adjustment necessary for an expanded dialysis bundle?

Congress has required CMS to expand the Medicare outpatient prospective payment system (PPS) for dialysis services to include as many drugs and diagnostic procedures provided to end stage renal disease (ESRD) patients as possible. One important implementation question is whether dialysis facility case mix should be reflected in payment. We use fiscal year (FY) 2000 cost report and patient billing and clinical data to determine the relationship between costs and case mix, as represented by several patient demographic, diagnostic, and clinical characteristics. Results indicate considerable variability in costs and case mix across facilities and a significant and substantial relationship between case mix and facility cost, suggesting case mix payment adjustment may be important.