Joshi S, et al. - Via an analysis of variation in hospital readmission rates for specific conditions among Medicare beneficiaries, experts quantified the contribution of regression to the mean (RTM) to decreasing readmission rates at hospitals initially penalized under the Hospital Readmissions Reduction Program (HRRP). A total of 3,258 hospitals were involved in the study. For the three target conditions, hospitals with excess readmission ratios (ERRs) of greater than 1.0 during the fiscal year 2013 measurement window showed reductions in ERRs in the following 3 years, whereas hospitals with ERRs of no greater than 1.0 displayed rises. The same outcomes, with ERR variations of comparable magnitude, were observed when the analyses were redone using an alternative measurement window that predated the HRRP and followed up hospitals for 3 years. In ERRs, 74.3% to 86.5% of the improvement for penalized hospitals was explained by RTM by corresponding actual variations in ERRs with expected alterations because of RTM. Thus, during the measurement window for the first year of the HRRP, most of the reductions in readmission rates in hospitals with high rates seemed to be because of RTM. These conclusions appear to call into question the idea of an HRRP policy's impact on readmissions.