Discussion
LBP, pain
OSTEOARTHRITIS OF THE KNEE
The current study aimed to investigate the presence of groups of patients with distinct trajectories of adherence to HBE recommendations among people with LBP and to identify differences in baseline characteristics between groups. Three groups with distinct trajectories were identified. The “low declining adherence” group started with moderate adherence and declined to almost no adherence over the course of treatment. The “low increasing adherence” group started at around the same level of moderate adherence as the “low declining adherence” group, but adherence increased over time to almost 80 points on the EXAS. The “high stable adherence” group started with the highest adherence, and adherence declined slowly to approximately the same level as the “low increasing adherence” group at the end of the trajectory. None of the baseline characteristics showed statistically significant differences between the identified trajectory classes, including treatment group allocation in the intervention study. It is noteworthy that the width of the confidence intervals of the trajectories increases sharply as the number of treatments increases. This is because the number of patients still receiving treatment declines quickly after 6 treatment sessions reducing the precision of estimated trajectories past this point. To our knowledge, the current study is the first to measure adherence trajectories to HBE recommendations in patients with LBP during treatment by a physical therapist, making direct comparison of our results with similar studies in patients with LBP difficult. However, trajectories of adherence were previously investigated in patients with osteoarthritis of the knee and/or hip.In patients with osteoarthritis of the knee and/or hip, differences between the identified groups were found for pain, function, and self-efficacy. This is in line with studies investigating factors associated with adherence but is in stark contrast to the findings from the current study.Another explanation is that adherence to HBE recommendations during treatment is mainly determined by factors outside of the patient, such as environmental factors, social factors, intervention-related factors, or therapist-related factors. Indeed, a number of the factors related to adherence reported in the literature are external factors not directly related to the patient.