Who responds to first-line interventions delivered in primary care? a responder - non-responder analysis on people with knee or hip osteoarthritis treated in Swedish primary cares

Abstract

Purpose: According to international and national guidelines, patient education and individualized exercise are core treatments which should be offered all patients with osteoarthritis (OA) in knee and hip as early as possible during the course of the disease. The Swedish Better Management of Patients with Osteoarthritis (BOA) is a self-management program following the guidelines who have demonstrate improvements in pain at three- and twelve-month follow-up in individuals with knee and hip OA. The individual pain reduction in the BOA program vary greatly and is depending on participants’ characteristics as well as the joint affected; patients with knee OA respond better than patients with hip OA. Individual factors like OA location (hip or knee), sex, age, body mass index (BMI), comorbidity, previously care, and patient reported outcomes at baseline has previously been shown to be associated with outcome after a physiotherapy (PT) intervention. However, although these factors have been analysed, little is known about who is responding to a self-management program like the BOA program conducted in a real world setting both at short and at a long-term perspective. Therefor the aims of this study were; 1) to analyse and compare the baseline characteristics of responders versus non-responders at 3 and 12 month from the enrolment in a first-line intervention delivered nationwide in Sweden, 2) to access the proportion of participants who respond to the intervention at both follow-ups (OA). Methods: This was an observational registry-based study with data from the Swedish BOA-registry from 2008 to 2016. The BOA registry contains data from individuals with knee and hip OA who have participated in a first-line intervention including education and individual adapted exercise. All the patients taking part in BOA receive two theoretical group sessions led by a PT focusing on the disease pathophysiology and on the benefit of exercise, including self-management advice and strategy to incorporate exercise into daily life. Participants can then take part in a face to face session with a PT which designs an exercise program based on the patient’s specific needs and goals. Finally, participants can decide to perform their exercise program at home or under the supervision of a PT in 12 group sessions of the duration of 1h provided twice per week for a total of 6 weeks. A total of 18964 individuals with knee OA and 7767 individuals with hip OA with complete data from baseline, 3- and 12-month follow-up were included in the analyses. The Numeric rating scale (NRS) for pain were used to evaluate the pain at baseline, 3- and 12-month follow-up. Participants were defined as a responder if they had a 33% decrease in NRS pain. This cut-off has previously been validated in a sample of individuals with OA and other chronic rheumatic conditions against a scale their a decrease of 15 % were defined as slightly better and 33 % were defined as much better. Individual factors at baseline for responders and non-responders are presented as frequencies (percentage) or mean and standard deviation (SD). Differences between responder and non-responder were calculated by chi-square test for categorical variables and independent t-test for continuous variables. All analyses were stratified by joint (knee/hip). Results: The proportion of individuals who were defined as responder with knee OA at 3- and 12-month were 43 % and 37 % respectively, while among people with hip OA were 38 % and 29 % respectively. There was a statistically significant difference between individuals defined as responder versus non-responder. Individuals with knee OA responding to the treatment were in average younger, had a lower BMI, unilateral OA, a higher education level and fewer had previous been treated by a PT or had previous surgery to the knee. Responders with knee OA reported at baseline a higher pain intensity, a higher quality of life and a higher self-efficacy while fewer responders reported pain every day or all the time and had willingness of surgery. Individuals with hip OA responding to the treatment at 3-month follow-up where in average younger, had a lower BMI and a higher education level. Responders with hip OA reported at baseline a higher pain intensity, a higher quality of life, a higher self-efficacy and fewer reported pain every day or all the time and had willingness of surgery. Adding to this, fewer responders with hip OA at 12-month follow up had previously been treated by a PT and reported intake of OA medication. (Table 1) Conclusions: Individual factors at baseline differed between responders and non-responders, even though the differences were statistically significant they can be considered small and not clinical important. A self-management program with education and individual exercise, according to the Swedish BOA program, should be recommended as a first line treatment to all individuals with knee or hip OA independently of individual factors.