Effect of Body Mass Index and Psychosocial Traits on Total Knee Replacement Costs in Patients with Osteoarthritis

J Rheumatol. 2016 Aug;43(8):1600-6. doi: 10.3899/jrheum.151301. Epub 2016 Jun 15.


Objective: Clinical and psychosocial attributes are associated with clinical outcomes after total knee replacement (TKR) surgery in patients with osteoarthritis (OA), but their relationship with TKR-related costs is less clear. Our objective was to evaluate the effect of clinical and psychosocial attributes on TKR costs.

Methods: We conducted a 6-month prospective cohort study of patients with knee OA who underwent TKR. We examined baseline demographic, clinical [body mass index (BMI) and comorbidities], and psychosocial attributes (social support, locus of control, coping, depression, anxiety, stress, and self-efficacy); baseline and 6-month OA clinical outcomes [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function]; and 6-month direct and indirect TKR-related costs. Multiple regression was performed to identify determinants of TKR-related costs.

Results: We included 212 patients; 66% were women, 71% were white, and the mean age was 65.2 years. The mean baseline WOMAC pain score was 55 (SD 19) and WOMAC function score was 54 (SD 20). Mean total TKR-related costs were US$30,831 (SD $9893). Multivariate regression analyses showed that increasing BMI and anxiety levels and decreasing levels of positive social interactions were associated with increased costs. A lower cost scenario with a lower range of normal BMI (19.5), highest positive social interaction, and no anxiety predicted TKR costs to be $22,247. Predicted costs in obese patients (BMI 36) with lowest positive social interaction and highest anxiety were $58,447.

Conclusion: Increased baseline BMI, anxiety, and poor social support lead to higher TKR-related costs in patients with knee OA. Preoperative interventions targeting these factors may reduce TKR-related costs, and therefore be cost-effective.


Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptation, Psychological*
  • Aged
  • Anxiety / psychology
  • Arthroplasty, Replacement, Knee / economics
  • Arthroplasty, Replacement, Knee / psychology*
  • Body Mass Index*
  • Depression / psychology
  • Female
  • Humans
  • Internal-External Control
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / economics
  • Osteoarthritis, Knee / psychology
  • Osteoarthritis, Knee / surgery*
  • Prospective Studies
  • Self Efficacy*
  • Social Support*
  • Stress, Psychological / psychology