Identifying Treatment Effect Modifiers in the STarT Back Trial: A Secondary Analysis

Abstract

Identification of patient characteristics influencing treatment outcomes is a top low back pain (LBP) research priority. Results from the STarT Back Trial support the effectiveness of prognostic stratified care for LBP compared to current best care, however patient characteristics associated with treatment response have not yet been explored. The purpose of this secondary analysis was to identify treatment-effect modifiers within the STarT Back Trial at 4 months follow-up (n=688). Treatment response was dichotomized using back-specific physical disability measured by the Roland-Morris Disability Questionnaire (≥7). Candidate modifiers were identified using previous literature and evaluated using logistic regression with statistical interaction terms to provide preliminary evidence of treatment-effect modification. Socioeconomic status (SES) was identified as an effect modifier for disability outcomes (OR = 1.71, P=.028). High SES patients receiving prognostic stratified care were 2.5 times less likely to have a poor outcome compared to low SES patients receiving best current care (OR = 0.40, P=.006). Education level (OR = 1.33, P=.109) and number of pain medications (OR = 0.64, P=.140) met our criteria for effect modification with weaker evidence (0.20>P≥0.05). These findings provide preliminary evidence for SES, education, and number of pain medications as treatment-effect modifiers of prognostic stratified care delivered in the STarT Back Trial. Perspective This analysis provides preliminary exploratory findings about the characteristics of patients who might least likely benefit from targeted treatment using prognostic stratified care for low back pain.

The Impact of Inadequate Health Literacy in a Population with Musculoskeletal Pain

“…One included study reported an association between low health literacy, and more pain and functional limitation (Kim, 2009), although Loke et al (2012) identified many methodological weaknesses in the included studies. A UK back pain trial reported that participants with low socioeconomic status (based on occupation) benefitted less from a prognostic stratified care intervention for low back pain than those with high socioeconomic status (Beneciuk et al, 2017). Our results may partly explain these findings.…”

“…Self-management programs require patients to have a high level of participation and engagement (Adams, 2010). There is growing evidence that factors related to health equity (e.g., socioeconomic disadvantage, inadequate health literacy) may be partly the reason that some patients benefit less from musculoskeletal self-management interventions (Beneciuk et al, 2017; Kapoor, Eyer, & Thorn, 2016).…”

Treatment monitoring as a component of psychologically informed physical therapy: A case series of patients at high risk for persistent low back pain related disability

“…Finally, future research should consider how other non-psychological measures such as socioeconomic status 65 and race 66 impact treatment monitoring to provide further insight to the unexplained variance in pain and disability outcomes. In this case series, we included an index consisting of 8 different components including lumbar flexion, extension, pelvic flexion, lateral flexion, straight leg raising, spinal tenderness, bilateral active straight leg raise, and sit-up.…”

The heterogeneous effect of short-term transfers for improving ART adherence among HIV-infected Tanzanian adults

“…To determine statistical significance, we examined the relative excess risk due to interaction (RERI) p-value (Rothman, 2008; VanderWeele, 2014). Similar to standard subgroup analyses (Beneciuk et al, 2017), we specified a p<0.20 threshold to indicate potential effect heterogeneity. All analyses were conducted using Stata-14 (College Station, Texas).…”