Predictors of inpatient rehabilitation after total knee replacement: an analysis of private hospital claims data

To the Editor: Schilling and colleagues1 state that the Australasian Rehabilitation Outcomes Centre (AROC) — the national rehabilitation clinical quality registry for Australia and New Zealand — does not routinely collect data on post‐surgery outcomes for private total knee replacement (TKR) recipients. This statement is factually incorrect. All private inpatient rehabilitation services in Australia are members of AROC and routinely submit data (including functional outcomes as assessed by a functional independence measure) describing all episodes of rehabilitation they provide. More specifically, over the period described by Schilling and colleagues,1 AROC received data on outcomes for 93 278 TKRs receiving private rehabilitation. If we restrict the AROC data to match the study data (patients aged 40–89, single TKR, first admission), AROC received data describing 76 847 privately rehabilitated TKRs.

In rehabilitation, the Australian National Subacute and Non‐Acute Patient Classification2 is routinely used to classify episodes into resource‐homogeneous groups. In interrogating the AROC TKR data, we concur with Schilling et al1 that the average length of stay in rehabilitation has been declining, with this decline accelerating over the past 5 years. Concurrent with the decline in length of stay, the functional change achieved (both absolute and relative) during rehabilitation has been increasing, and has in fact accelerated over the past 5 years. Achieving more functional change in a shorter length of stay shows that services are becoming more efficient while also continuing to produce positive outcomes for their patients.

Moreover, it is also factually incorrect that AROC does not collect data outside of the inpatient setting. In fact, AROC also runs an ambulatory benchmarking initiative, and while coverage is not 100%, it is growing. There are currently 35 private ambulatory rehabilitation services that participate and routinely provide data describing their ambulatory rehabilitation outcomes.

In conclusion, we suggest that while the authors provide an interesting analysis, it is incomplete, given that they did not include function — the key driver of cost and outcomes in rehabilitation — as one of the variables they used.