293: Smallest Worthwhile Improvement in Physical Function Expected from Low Back Pain Apps

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic primary musculoskeletal pain, Non-pharmacological treatments, Physiotherapy (e.g. exercise, rehab), Digital Health Technologies

Background and Aims: The smallest worthwhile improvement has been proposed as a comprehensive measure to address the inherent limitations of earlier methods of estimating treatment effects and determining clinical meaningfulness (1). Despite the increasing popularity of smartphone applications (apps) in musculoskeletal health research, the smallest worthwhile improvement in physical function expected from people with chronic non-specific low back pain (LBP) using apps remains unknown. The purpose of this cross-sectional study was to investigate the smallest worthwhile improvement of smartphone apps for improving physical function in people with chronic non-specific LBP.

Methods: A purposive sample from the My Back Exercise App randomised controlled trial (2) was included. At baseline, participants nominated the smallest change in physical function, measured by the Patient-Specific Functional Scale on a 0-30 scale, that they would need to achieve following a 6-week, app-delivered self-management program to consider it worthwhile. The smallest worthwhile improvement was assessed using a modified benefit-harm trade-off methodology (3), accounting for patient values and weighing the benefits, harms, risks, inconveniences, and costs of the intervention.

Results: A total of 380 participants were included (mean age: 66.5 years, SD 10; 52.1% females). At baseline, participants reported an average pain intensity of 4.5/10 (SD 2.1) and a mean PSFS score of 12.8 (SD 5.7). The smallest improvement in physical function that participants with chronic LBP needed to experience to consider an app worthwhile was 7.6 points (SD: 4.5, range: 0-24), representing 25% of the total function score and 59% of the participants’ mean function score at baseline. People with lower levels of physical function tended to expect greater improvements.

Conclusions: People with chronic LBP require at least 59% improvement in physical function to consider the benefits, harms, risks, inconveniences, and costs of an app-based self-management program worthwhile, with greater improvements expected by people with lower physical function. These findings can inform the design and testing of novel app-delivered self-management programs for people with chronic LBP. Similarly, these findings should be considered during all stages of health technology assessment, from conducting sample size calculations to interpreting clinical trial results of smartphone applications designed for people with chronic LBP.

References: 1. Barrett B, Brown R, Mundt M, Dye L, Alt J, Safdar N, et al. Using benefit harm tradeoffs to estimate sufficiently important difference: the case of the common cold. Med Decis Making. 2005;25(1):47-55.

2. Silveira AMC, Comachio J, Mesa-Castrillon C, Roberts K, Beckenkamp P, Ho EK, et al. My Back Exercise app: an automated exercise intervention supported by educational notifications, a sleep programme and diet advice to improve function in people with chronic non-specific low back pain – protocol for a superiority, adaptive multi-arm multi-stage randomised controlled trial. BMJ Open. 2025;15(7):e098324.

3. Fritsch CG, Ferreira PH, Lung T, McLachlan AJ, Ferreira ML. The smallest worthwhile change on function from a self-management intervention for non-persistent low back pain. Eur Spine J. 2023;32(9):3272-79.

Presenting Author: Anelise Moreti Cabral Silveira
Submitting Author: Anelise Moreti Cabral Silveira

Senior Author: Paulo Ferreira

IASP 2026 Global Year theme of Neuropathic Pain: No

• Anelise Moreti Cabral Silveira - 1Faculty of Medicine and Health, Sydney Musculoskeletal Health, The University of Sydney, Sydney, Australia; 2Musculoskeletal Research Hub, Charles Perkins Centre, The University of Sydney, Sydney, Australia; 3The George Institute for Global Health, UNSW Sydney, Sydney, Australia
• Manuela L Ferreira - 3The George Institute for Global Health, UNSW Sydney, Sydney, Australia; 4Medicine & Health, University of New South Wales, Sydney, Australia
• Paula R Beckenkamp - 1Faculty of Medicine and Health, Sydney Musculoskeletal Health, The University of Sydney, Sydney, Australia; 2Musculoskeletal Research Hub, Charles Perkins Centre, The University of Sydney, Sydney, Australia
• Isabella Shannon - 1Faculty of Medicine and Health, Sydney Musculoskeletal Health, The University of Sydney, Sydney, Australia; 2Musculoskeletal Research Hub, Charles Perkins Centre, The University of Sydney, Sydney, Australia
• Gayatri Iyer - 1Faculty of Medicine and Health, Sydney Musculoskeletal Health, The University of Sydney, Sydney, Australia; 2Musculoskeletal Research Hub, Charles Perkins Centre, The University of Sydney, Sydney, Australia
• James Zouch - 1Faculty of Medicine and Health, Sydney Musculoskeletal Health, The University of Sydney, Sydney, Australia; 2Musculoskeletal Research Hub, Charles Perkins Centre, The University of Sydney, Sydney, Australia
• Michelle Hall - 5The Kolling Institute, Faculty of Medicine and Health, Sydney Musculoskeletal Health, The University of Sydney, Sydney, Australia
• Paulo Ferreira - 1Faculty of Medicine and Health, Sydney Musculoskeletal Health, The University of Sydney, Sydney, Australia; 2Musculoskeletal Research Hub, Charles Perkins Centre, The University of Sydney, Sydney, Australia