Osteoarthritis Self-Management Reveals Diverse Pain Trajectories at 52 Weeks

Evaluation of a digital self-management program for osteoarthritis (OA) over 52 weeks identified several pain trajectories and encouraged improvements for most participants, with specific patient characteristics indicative of increased likelihood of a worsening pain trajectory over time, according to study results published in Pain Medicine.

As a leading cause of chronic pain and functional limitation in older adults, osteoarthritis is managed primarily via physical exercise and education, available either by face-to-face instruction from providers or digitally. Although prior studies have recognized the effectiveness of both formats, recent meta-analyses have questioned their overall clinical impact.

In an effort to identify subgroups of patients with OA who may derive the most benefit from treatment, investigators explored pain trajectories over a 52-week period among patients participating in a digital first-line exercise program for self-management of hip and knee OA.

Using an observational longitudinal study design, they collected data from all patients who were engaged from January 2019 to September 2021 in the Joint Academy®, a first-line exercise and education program for hip and knee OA in Sweden.

Nearly all (95%) patients had a prior radiographic and/or clinical diagnosis of hip or knee OA from a physician or physical therapist. Patients had been referred to the program by their local orthopedic surgeon or physiotherapist or joined in response to online advertisements. Patients who had engaged in the program for less than 4 weeks were excluded.

The digital program, delivered as a smartphone app, is targeted towards exercise, physical activity, and education. Lessons are provided on OA, physical activity, and self-management, and learning is supported by short quizzes. Patients also receive a personalized exercise program that is adjusted over the duration of their participation in the program. They are supervised by a physical therapist, and all physical therapists participating in the program are certified in OA knowledge.

The primary outcome was knee and/or hip pain, measured at baseline and weekly thereafter up to 52 weeks, using the 11-point Numeric Rating Scale (NRS) (with 0 indicating no pain and 10 representing the worst possible pain); severity was categorized as mild (NRS 1-4), moderate (NRS 5-6), or severe (NRS 7-10). A minimum NRS reduction by 1 unit over time was considered clinically significant.

Several covariates were considered in the analysis to identify their association with pain trajectories. All variables were self-reported by patients at time of enrollment and consisted mainly of demographic information, place of residence, health-related variables (physical function/activity, activity impairment, etc), and health conditions (doctor-diagnosed diabetes, lung diseases, cardiovascular diseases, rheumatoid arthritis, and balance issues).

A total of 16,274 patients participated in the digital OA self-management program for at least 4 weeks (and up to 52 weeks). The majority (75.1%) of patients were women, and mean (SD) patient age was 64.2 (9.1) years. There were 59.6% of patients with knee OA and 40.4% with hip OA.

A 4-class model was identified as the optimal representation of pain trajectories, and several distinct patterns were found: severe [pain]-persistent (12%), upper moderate [pain]-improved (24%), low moderate [pain]-largely improved (34%), and mild [pain]-largely improved (30%). That is, 88% of patients in the study sample experienced an improvement in their pain intensity. Higher pain levels at baseline were associated with poorer outcomes, higher BMI, lower education, and lower physical activity.

Multinomial logistic regression highlighted several factors (all measured at enrollment) associated with greater probabilities of OA pain being classified as “mild-largely improved”; these included older age, male sex, lower BMI, better physical function, lower activity impairment, less anxiety/depression, higher education, knee OA, no walking difficulties, no wish for surgery, and higher physical activity. Notably, the most significant predictor of variations in pain trajectories was activity impairment, accounting for approximately 10.7% of variation, with patients who requested surgery and patients with walking difficulties as the second and third most important predictors, respectively.

Subgroup analysis supported the 4-class model as being the most optimal for assessment of both knee and hip OA. The main difference observed was that a higher percentage of patients with hip OA were designated as “severe pain-persistent,” aligning with the main study analysis.

Study limitations include the self-reporting of data, which may have made the study prone to bias, and the potential influence of concurrent therapies (pain medications, other face-to-face digital treatments) on patients’ pain trajectories. Additionally, use of a single pain dimension (intensity) may not provide complete information about symptom progression and health outcomes.

The investigators concluded, “Our findings suggest the importance of early provision of core first line treatments for OA prior to developing severe pain, activity limitations, walking difficulties, poor health status and a wish for surgery.” They added that the study “also provides insights on some important predictors of pain trajectory classes which can be used for modification of the digital program.” However, they cautioned, “For a better prediction of pain trajectory, further detailed data needs to be collected.”

This article originally appeared on Clinical Pain Advisor