Predictive Factors for Improvements in Pain and Physical Function After Progressive Resistance Training or Neuromuscular Exercise in Hip Osteoarthritis. An Exploratory Analysis From the Hip Booster Trial

OBJECTIVE: To investigate associations between baseline characteristics and changes in hip pain and physical function after exercise therapy in patients with hip osteoarthritis (OA).

DESIGN: Prospective cohort study.

METHOD: Exploratory analyses were conducted to assess the relationship between baseline characteristics and changes in pain and activities of daily life subscales from the Hip disability and Osteoarthritis Outcomes Score questionnaire (HOOS). Data were obtained from a randomized controlled trial that compared 12 weeks of progressive resistance training to neuromuscular exercise. Predictive factors assessed were baseline levels of dependent variables, prior exercise, use of analgesics, baseline muscle power, baseline 30-second chair stand test, sex, age, and BMI. Multivariate linear and binary regression models were conducted to estimate the adjusted regression coefficients.

RESULTS: Among 150 participants, changes in HOOS pain and HOOS ADL function (0-100 points, higher is better) were positively associated with female sex (β [95% CI]: 4.43 [-1.84; 10.70] and 4.70 [-1.50; 10.90]) and negatively associated with baseline levels of the dependent variable (β [95% CI]: -.45 [-.61; -.29] and -.44 [-.58; -.30]), prior exercise therapy (β [95% CI]: -7.27 [-13.48; -1.06] and -5.46 [-11.66; .74]), use of analgesics (β [95% CI]: -5.67 [-10.39; -.95] and -7.24 [-11.72; -2.76]), and BMI (β [95% CI]: -.59 [-1.07; -.11] and -.55 [-1.03; -.08]).

CONCLUSIONS: Female sex, no prior exercise therapy, no use of analgesics, lower BMI, and worse pain and physical function were associated with greater effects of exercise on pain and physical function in hip OA. These findings should be interpreted with caution due to study limitations.