Do Patient Outcomes Vary by Patient Age Following Primary Total Hip Arthroplasty?

Abstract

Background: Multiple authors have sought to determine what patient characteristics influence outcome after total hip arthroplasty (THA). Age has shown no effect on outcome in some evaluations, while others have reported higher functional improvement in younger patients. The aim of this study was to determine if outcome after THA varies based on patient age.

Methods: A prospective, multicenter cohort of 7,934 unilateral primary THA patients from the FORCE-TJR comparative effectiveness consortium was evaluated. Demographic data, comorbid conditions, and Patient-Reported Outcome Measures, including (HOOS), HOOS-12, HOOS JR, and SF-36 (PCS) and (MCS), were collected preop and at 1-year postop. Descriptive statistics were generated, stratified by age (<55 years [younger adult], 55-64 years [older adult], 65-74 years [early elder], and ≥75 years [late elder]), and differences in pain, function, and quality of life among the 4 age groups were evaluated. A multivariate regression model with 95% confidence interval (CI) was used to assess the role of patient age as a predictive factor for HOOS pain and function scores reported 1 year after primary THA.

Results: Prior to surgery, younger patients (<55 years) reported worse pain, function, and quality of life than the other 3 patient groups. At 1 year after THA, younger patients (<55 years) reported slightly worse pain and quality of life but better function scores than the 3 older patients' groups. Younger patients (<55 years) achieved higher baseline to 1-year pain, and function score changes when compared to the older patients' groups. The quality of life score changes was not different among the 4 age groups. The differences in 1-year postop scores (ranging from 2.74 to 8.46) and the magnitude of score changes from baseline to 1 year (ranging from 1.9 to 5.85), although statistically significant (P < .001), did not reach the minimal clinically important difference (MCID). The multivariate regression analysis shows that age is a significant predictor for pain at 1 year but not for function. Although HOOS pain score is predicted to be higher by 4.38 points (less pain) 1 year after THA in older patients (≥75), when compared to younger patients (<55 years), again the difference is well below the MCID and is clinically insignificant.

Conclusion: Although there are statistically significant differences in pain relief, functional improvement, and quality of life between younger and older patients among different patients' age groups, there is no clinically significant difference. THA provides an improvement in quality of life by decreasing pain and increasing function in all 4 age groups, with large improvements in Patient-Reported Outcome Measures scores (>2 standard deviations) without clinically significant age-related differences in THA outcome at 1 year.

Keywords: function; old age; patient-reported outcome; quality of life; total joint replacement; young age.