Quality differences between private for-profit, private non-profit and public hospitals in Norway: a retrospective national register-based study of acute readmission rates following total hip and knee arthroplasties

OBJECTIVES To compare the quality of care-using unplanned acute hospital readmissions as a quality measure-among patients treated at private for-profit hospitals (PFPs), private non-profit hospitals (PNPs) and public hospitals (PUBs) in Norway. DESIGN A retrospective comparative study using the Norwegian Patient Register. Readmissions were evaluated by logistic regressions both using adjustment for various patient-level and other covariates, and a two-stage model using distance as an instrumental variable. SETTING The Norwegian healthcare system. POPULATION All publicly financed patients having primary total hip (37 897 patients) or primary total knee arthroplasty (25 802 patients) at one of the three hospital types from 2009 to 2014. PRIMARY OUTCOME MEASURE 30-day unplanned acute hospital readmission rate. RESULTS We found highest readmission rates among PUBs and lowest among PFPs, for both procedures. However, the patients were on average more than 2 years younger at PFPs. PFPs also treated the least severe patients, while PUBs treated the most severe. Using adjustment for various patient-level and other covariates, compared to PUBs, both PFPs and PNPs had lower odds of readmission following both procedures. However, using the instrumental variable method, the only significant difference found was a lower odds of readmission at PNPs among hip patients when compared with PUBs. No patients in our data set were readmitted to PFPs, those originally treated at PFPs were readmitted to either PNPs or PUBs, and PUBs received most of the readmitted patients across hospital types. CONCLUSIONS Quality differences between hospital types were small; however, PNPs had significantly lower readmission rates compared with PUBs among patients having total hip arthroplasty. PUBs received the larger part of the readmitted patients across hospital types and thus play an essential role in the care of more complex patients and for readmissions, regardless of any quality differences.