Effectiveness of Total Hip Arthroplasty for Patients With Osteoarthritis, a Target Trial Emulation Study

The aim of this study is to assess the effect of total hip arthroplasty on hip disability and pain compared to non-surgery in patients with hip osteoarthritis, using target trial emulation to emulate a randomized controlled trial.

The ideal research design to investigate effectiveness of total hip arthroplasty (THA) would be to randomize patients between surgery and (delayed) non-surgery. Such a randomized controlled trial (RCT) is deemed unethical due to the effect size of THA shown in observational studies. In this study a target trial is specified (a randomized controlled trial between THA and non-THA) and the target trial is emulated using observational data of 2 dutch hospitals participating in the value based health care (VBHC) programme for hip osteoarthritis. The objective of this study is to compare the effect of THA surgery on hip disability and pain between patients that did or did not receive THA surgery during the Covid-19 pandemic. It is hypothesized that THA is effective in restoring hip function and reduction of pain compared to the control group. The effect of THA has not been demonstrated by means of an RCT before. This study can contribute to the available evidence by assessing causal effectiveness of THA by means of RCT target trial emulation. As a secondary aim, the assumption of pseudo-random group allocation will be assessed. Logistic regression analysis will be used to test whether group allocation is independent of patient characteristics (age, sex, HOOS-PS baseline, NRS baseline, physical therapy before baseline and follow-up time.