Adults with knee osteoarthritis and at least one comorbid condition significantly improved their physical function after a comorbidity-targeted 20-week exercise program in a randomized, controlled trial of 126 patients.
“Guidelines on knee osteoarthritis do not provide guidance on tailoring exercise therapy to the presence of comorbidity,” wrote Mariëtte de Rooij of the Amsterdam Rehabilitation Research Center and her colleagues. “In clinical practice, comorbidity is a frequent reason to exclude patients from exercise therapy,” they noted.
The researchers randomized 126 adults with knee osteoarthritis and at least one of the following comorbidities: coronary disease, heart failure, type 2 diabetes, chronic obstructive pulmonary disease, or obesity (body mass index 30 kg/m2 or higher). The treatment group participated in a 20-week exercise program adapted to their comorbidities and physical limitations. Each program included aerobic exercise and strength training in two 30- to 60-minute sessions per week, supervised by a physical therapist. The control group received their current medical care for knee osteoarthritis and were placed on a waiting list for exercise therapy. Baseline characteristics and demographics were similar between the two groups, with mean ages of about 63 years, 81% with bilateral knee osteoarthritis, and a mean duration of symptoms of about 9 years. Patients with absolute contraindications for exercise therapy (such as myocardial infarction within the past 3 months) were excluded (Arthritis Care Res. 2016 Aug 26. doi: 10.1002/acr.23013).
In a follow-up visit 3 months after the end of the exercise program, patients in the treatment group averaged an 11.6-point (33%) improvement on the Western Ontario and McMaster Universities Osteoarthritis Index physical function subscale and a 59-meter (15%) improvement on the 6-minute walk test, compared with controls.
In addition, patients in the treatment group reported a 1.7-point (27%) improvement on the Numeric Rating Scale for knee pain severity. No serious adverse events related to the exercise therapy were reported.
The exercise programs were adapted to the patients by adjusting the frequency, intensity, timing, and type (FITT) of exercises, educating patients about the impact of exercise on their comorbidities, and by coaching patients to ease fears of exertion or to encourage weight loss.
“This is the first study showing that tailored exercise therapy is efficacious in improving physical functioning and is safe in patients with knee osteoarthritis and severe comorbidities,” the researchers said. The findings were limited by several factors including a small sample size that made it impossible to analyze the impact of exercise on any specific comorbidity, and the lack of cost-effectiveness data. However, “the results should encourage clinicians to consider exercise therapy as a treatment option for patients with knee osteoarthritis, even in the presence of severe comorbidity,” the researchers added.
The trial was supported by the Royal Dutch Society for Physical Therapy and Merck Sharp & Dohme. The researchers had no financial conflicts to disclose.