The role of pain duration and pain intensity on the effectiveness of app-delivered self-management for low back pain: Secondary analysis of the SELFBACK randomized controlled trial (Preprint)
Authors: Nordstoga Anne Lovise , Aasdahl Lene , Sandal Louise Fleng , Dalager Tina , Kongsvold Atle Austnes , Mork Paul Jarle , Nilsen Tom Ivar Lund 
Published: June 2022

BACKGROUND

Clinical guidelines for non-specific low back pain (LBP) recommend self-management tailored to individual needs and capabilities as a first-line treatment. mHealth solutions are a promising method for delivering tailored self-management interventions to patients with non-specific LBP. However, it is not clear if the effectiveness of such self-management interventions depends on patients’ initial pain characteristics. High pain intensity and long-term symptoms of LBP have been associated with an unfavorable prognosis, and current best evidence indicates that long-term LBP (lasting more than 3 months) requires a more extensive treatment approach compared to more acute LBP. The artificial intelligence-based SELFBACK app supports tailored and evidence-based self-management of non-specific LBP. In a recent randomized controlled trial, we showed that individuals who received the SELFBACK app in addition to usual care had lower LBP-related disability at 3 months follow-up compared to those who received usual care only. This effect was sustained at 6 and 9 months.

OBJECTIVE

To explore if baseline duration and intensity of LBP influence the effectiveness of the SELFBACK intervention in a secondary analysis of the SELFBACK randomized controlled trial.

METHODS

In the SELFBACK trial, 461 adults (≥18 years) who sought care for non-specific LBP in primary care or at an outpatient spine clinic were randomized to receive the SELFBACK intervention adjunct to usual care (n=232) or usual care alone (n=229). In this secondary analysis, the participants were stratified according to duration of the current LBP episode at baseline (≤12 weeks vs >12 weeks) or baseline LBP intensity (≤5 points vs >5 points) measured by a 0-10 numeric rating scale (NRS). Outcomes were LBP-related disability measured by the Roland Morris Disability Questionnaire (0-24 point scale), average LBP intensity, pain self-efficacy, and global perceived effect. To assess whether duration and intensity of LBP influenced the effect of SELFBACK, we estimated the difference in treatment effect between the strata at 3 and 9 months follow-up with a 95% confidence interval.

RESULTS

Overall, there was no difference in effect for patients with different duration or intensity of LBP at either 3 or 9 months follow-up. However, there was suggestive evidence that the effect of the SELFBACK intervention on LBP-related disability at 3 months follow-up was largely confined to people with the highest vs the lowest LBP intensity (mean difference between the intervention and control group; -1.8 (95% CI -3.0 to -0.7) vs 0.2 (95% CI -1.1 to 0.7), respectively), but this was not sustained at 9 months follow-up.

CONCLUSIONS

The results suggest that the intensity and duration of LBP have negligible influence on the effectiveness of the SELFBACK intervention on LBP-related disability, average LBP intensity, pain self-efficacy and global perceived effect.

CLINICALTRIAL

The multicenter SELFBACK RCT is registered in Clinicaltrials.gov: (NTC03798288). Registered 7 January 2019.

INTERNATIONAL REGISTERED REPORT

RR2-10.2196/14720