Health-related quality of life in patients with osteoarthritis after total knee replacement: factors influencing outcomes at 36 months of follow-up.

OBJECTIVES

(1) To evaluate health-related quality of life (HRQL) in patients with severe osteoarthritis (OA) undergoing total knee replacement (TKR) and (2) to identify the influence of sociodemographic, clinical, intra-operative and postoperative variables on HRQL at 36 months after TKR.

DESIGN

Prospective study with a 36-month follow-up. Preoperative interviews were carried out with 90 in-patients. The disease-specific Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire was used to measure the health status. Sociodemographic, clinical, intra-operative degree of difficulty, in-patient and postoperative data were collected. Associations were analyzed using linear regression models.

RESULTS

Of the 90 potentially eligible patients, 67 (54 females, mean age 74.83, standard deviation [SD] 5.57) completed follow-up assessment. There were significant differences between preoperative and postoperative WOMAC pain, stiffness and function scores (P<0.001, P=0.005 and P<0.001, respectively). Variables retained in each of the models explained between 15% and 23% (R(2) adjusted) of the variability of each WOMAC dimension. Higher preoperative WOMAC scores were associated with greater postoperative improvement (P<0.001). Chronic musculoskeletal pain unrelated to knee OA was associated with higher WOMAC pain, stiffness and function dimension scores (P=0.004, P=0.029 and P=0.005, respectively). Severe (Class III) obesity (body mass index [BMI] 35-39.9) was associated with more pain (P=0.049).

CONCLUSIONS

In patients with severe OA, HRQL significantly improved at 36 months after TKR, especially in the pain dimension. Lower preoperative WOMAC scores, chronic pain unrelated to knee OA, and severe obesity negatively influenced postoperative WOMAC scores. This disease-specific questionnaire may help to identify patients at increased risk of negative outcomes after surgery.