Hospital- and patient-related characteristics determining length of hospital stay for hip and knee replacements.

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are among the most prestigious health care technologies. Their popularity has grown rapidly, and an increasing proportion of health care resources is allocated to them. We studied patient- and hospital-related factors that cause variation in a major determinant of hospital costs, the length of hospital stay (LOS) for THA and TKA. We gathered data on 10,288 hip and 5,173 knee patients with primary or secondary arthrosis from the Finnish Arthroplasty Register, which we linked with the Finnish Hospital Discharge Register. Patient- and hospital-related variations in LOS were explained using regression models. Of the patient-related factors, complications caused the greatest prolongation of hospital stay, but patient's age, gender, and charge category also influenced LOS. Hospital-related factors were major causes of LOS variation. In the hospitals the average case-mix-adjusted LOS ranged from less than a week to 3 weeks. The number of arthroplasties performed in hospital was inversely related to LOS. The within-hospital LOS figures for THA and TKA were strikingly similar and persistent.