Patient, not surgeon factors influence patient-centric outcomes after knee surgery

Aug 9 2012

By Sarah Guy, MedWire Reporter

Patient factors are more important than anything surgeons can control during total knee replacement surgery in the prediction of patient-reported outcome measures (PROMs), report UK researchers.

Better postoperative PROMs were seen in patients with the best levels of preoperative general health, disability, and depression/anxiety, although the best scores were seen for patients with the best preoperative PROMs scores, writes the team in the British edition of the Journal of Bone and Joint Surgery.

"These findings highlight the fundamental importance of adequate adjustment of the case-mix when comparing institutions and surgeons," say Paul Baker (Newcastle University, UK) and colleagues, who note that PROMs are increasingly used to supplement traditional outcome measures.

"In a climate of financial incentives, failure to recognize and make allowance for these factors could result in surgeons and providers selecting cases to obtain the best results. The danger could be that patients with significant comorbidities, poor mental health scores or reduced functional ability, for whom knee replacement could potentially be life-changing, may be denied surgery," they add.

The team analyzed a cohort of 22,691 patients who underwent total knee replacement surgery between 2008 and 2011 and who completed PROMs questionnaires before, and a minimum of 6 months after their surgery. PROMs includes the Oxford Knee Score (OKS) and EuroQol-5D scores (EQ-5D) to indicate knee-specific and general health outcomes, respectively.

The authors report a mean OKS improvement of 15.1 points (from 19.0 to 34.1, where 48.0 is the best score), and a mean EQ-5D change of 0.303 points (0.409 to 0.712, where 1.000 would denote perfect general health) across the cohort.

After multivariate analysis, only implant brand type (NexGen, Zimmer Inc, Warsaw, Indiana, USA vs "other") and hospital type (independent hospitals and independent surgical treatment centers vs National Health Service hospitals) from the surgeon-related factors significantly and positively, although modestly, affected outcome.

Conversely, the team reports that for every 1-point increase in preoperative OKS, the predicted change in OKS was a decrease by a significant 0.66 points. The corresponding predicted change in EQ-5D after a 1-point preoperative increase was a significant decrease of 0.89 points.

Having a preoperative disability, poor preoperative general health, depression, and moderate-severe anxiety were also all significant predictors for postoperative PROMs.

The increase in patient education and selectivity with regard to who performs their surgery "provides the motivation to improve outcomes, track productivity and foster inter-unit competition," conclude Baker et al.

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