Factors associated with a clinically significant improvement in health-related quality of life after total knee arthroplasty

Background: The aim was to identify independent preoperative factors associated with changes in health-related quality of life (HRQoL) following total knee arthroplasty (TKA), and whether these could be used as indicators for surgery. Methods: A retrospective study of 3127 TKA patients was undertaken that included 1194 (38.2%) male and 1933 (61.8%) female patients, with a mean age of 70.5 years (standard deviation 9.0). Patient demographics, body mass index and ASA grade, Oxford Knee Score (OKS) and EuroQol 5-dimension (EQ-5D) 3-level, which was used to assess HRQoL, were collected preoperatively and 2 years postoperatively. Results: When adjusting for confounding factors, obesity grade II (p = 0.002), ASA grade 3 (p = 0.002), and a better preoperative OKS (p < 0.001) or EQ-5D score (p < 0.001) were associated with a decreased improvement in the HRQoL at 2-years. A preoperative EQ-5D of < 0.8 (95.7% specific, AUC ≥ 67.0%) or an OKS of < 36 (97.1% specific, AUC ≥ 58.1%) was associated with a clinically significant improvement HRQoL. Patella resurfacing (n = 1454, 46.5%) was not independently associated with a clinical or statistically significant improvement in HRQoL. According to preoperative factors, no subgroup of patients benefited more from patella resurfacing according to improvement in their HRQoL. Conclusion: ASA grade 3, grade II obesity, a better preoperative EQ-5D or OKS were independently associated with a lesser improvement in HRQoL. The thresholds identified in the EQ-5D or OKS for a clinically significant improvement in HRQoL may be used as potential indicators for referral for TKA. Patella resurfacing was not independently associated with a clinically important improvement in HRQoL. Level of evidence: Retrospective diagnostic study, Level III.