We aimed to compare the performance of EQ-5D-3L and howRu for measuring outcome of hip and knee replacements, using the Oxford Hip Score (OHS) and the Oxford Knee Score (OKS) as gold standard. HowRu is a short generic PROM, with 4 questions, each having 4 responses. It is 37 words in length, compared with 230 for EQ-5D-3L.

METHODS:

Outcome was taken to be the difference between scores pre-surgery and 6-month post-surgery. A large set (59,000) of operations from NHS PROMs database (using EQ-5D-3L), was compared with a small set (116) of similar operations collected by MyClinicalOutcomes (MCO) using howRu.  Both sets completed the OHS (hips) or the OKS (knees).

RESULTS:

For hip replacement, the correlation (95% confidence limits) for change measured by OHS and howRu was r=0.77 (0.66-0.85); OHS and EQ-5D Index r=0.64 (0.63-0.64); OHS and EQ-VAS r=0.33 (0.32-0.34); and EQ-5D Index and EQ-VAS r= 0.31 (0.30-0.32).

For knee replacement, the correlation for change measured by OKS and howRu was r=0.86 (0.75-0.92); OKS and EQ-5D Index r=0.59 (0.58-0.60); OKS and EQ-VAS r=0.32 (0.31-0.33); and EQ-5D Index and EQ-VAS r=0.28 (0.27-0.29).

The magnitude of change (outcome) between pre-op and post-op scores on 0-100 scales (where 100 = best and 0 = worst state for each measure) for hip replacement in the NHS dataset were OHS 42.2; EQ-5D Index 26.0; and EQ-VAS 10.2. For the MCO dataset, OHS 43.9 and howRu