Outcome measures
obesity, Osteoarthritis, Knee Injury, pain
OBESITY, OSTEOARTHRITIS

Quality-Adjusted Life Years (QALYs), assessed by the EuroQol-5D-5 L (EQ-5D-5 L; 5 items), in which the patient can self-rate their level of severity on five domains (mobility, self-care, daily activities, pain/discomfort, and anxiety/depression).Average knee pain severity during walking in the past week, assessed by a NRS (score 0=no pain; 10=worst pain imaginable).Physical functioning, assessed by the subscale function in daily living (ADL) of the Dutch translation of the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire (score 0=maximal problems; 100=no problem).Costs, valued in accordance with the Dutch Manual of Costing,health care utilization:intervention-related costs (i.e., costs from the physical therapy sessions (valued using the Dutch tariff of €35,69 for physical therapists or €41,00/hour for manual therapists), supplemented for the ‘obesity subgroup’ of the experimental arm by the costs of the dietician sessions (valued using the Dutch tariff of €32,09/hour).other medical costs (valued using Dutch tariffs and, if these were unavailable, prices of professional organizations) further subdivided into:primary health care, other than the (experimental or control) intervention (e.g., general practitioner, acupuncturist);secondary health care (e.g., hospital, rehabilitation center);(prescribed and over-the-counter) medication (for knee OA only);costs related to reduced work ability, with costs valued using Dutch sex-specific price weightsabsenteeism costs (i.e., costs of being absent from work), valued in accordance with the friction cost approach (friction period: 12 weeks)presenteeism costs (i.e., costs of being less productive while being at work, based on the participant's work ability, assessed by the Work Ability Index-Single Item Scale (WAS) on a 0–10 scaleunpaid productivity costs (i.e., volunteer work, and domestic and educational activities that the participant was not able to perform), valued using a recommended Dutch shadow price of €15,14/hourinformal care (i.e., care by family, friends, or other volunteers that was provided to the participant), valued using a recommended Dutch shadow price of €15,14/hour.sport costs (e.g. sport shoes, fees for fitness center).Discounting of costs was not necessary due to the 12-month follow-up period of the trial.