Abstract
BACKGROUND: Adherence to home-based exercise (HBE) recommendations is critical in physiotherapy for patients with low back pain (LBP). However, limited research has explored its connection with clinical outcomes. This study examined how adherence to HBE relates to changes in physical function, pain intensity, and recovery from LBP in patients undergoing physiotherapy treatment. METHODS: Data from a multicenter cluster randomized controlled trial in the Netherlands involving patients with LBP from 58 primary care physiotherapy practices were used. Adherence to HBE was assessed with the Exercise Adherence Scale (EXAS) at each treatment session. Previously identified adherence trajectories served as a longitudinal measure of adherence and included the classes "declining adherence" (12% of participants), "stable adherence" (45%), and "increasing adherence" (43%). The main outcomes included disability (Oswestry Disability Index), pain (Numeric Pain Rating Scale), and recovery (pain-free for > 4 weeks), which were measured at baseline and after three months. Linear and binomial logistic regression analyses adjusted for confounders were used to examine adherence-outcome relationships. RESULTS: In the parent trial, 208 participants were included. EXAS scores were available for 173 participants, collected over a median of 4.0 treatment sessions (IQR 3.0 to 6.0). Forty-five (28.5%) patients considered themselves to have recovered after three months. The median changes in the Oswestry Disability Index and Numeric Pain Rating Scale were - 8 (IQR - 1 to -20) and - 2 (IQR - 0.5 to -4), respectively. The mean EXAS scores varied among patient classes: "declining adherence" (46.0, SD 19.4), "stable adherence" (81.0, SD 12.4), and "increasing adherence" (39.9, SD 25.3), with an overall mean of 59.2 (SD 25.3). No associations between adherence and changes in physical functioning or pain were found in the regression analyses. CONCLUSIONS: No association between adherence to HBE recommendations and changes in clinical outcomes in patients with LBP was found. These findings suggest that the relationship between adherence to HBE recommendations and treatment outcomes may be more complex than initially assumed. Further research using detailed longitudinal data combined with qualitative methods to investigate patient motivation and beliefs may lead to a deeper understanding of the relationship between adherence and clinical outcomes in patients with LBP.