Impact of different acute low back pain definitions on the predictors and on the risk of transition to chronic low back pain: a prospective longitudinal cohort study

Abstract

Inconsistencies in the identification of predictors for the transition from acute low back pain (aLBP) to chronic LBP (cLBP) may be attributed to the varying definitions of aLBP used in different studies. We investigated how adopting different aLBP definitions affects the set of predictors and the risk of transition to cLBP (LBP > 3 months that caused a problem for at least half the days in the past 6 months). We leveraged data from the ongoing prospective Quebec Low Back Pain Study to compose 3 aLBP groups at baseline: nonchronic (individuals not meeting the cLBP criteria, n = 788), acute (LBP < 3 months, n = 230), and new episode (LBP < 3 months preceded by ≥3 pain-free months, n = 182). The primary outcome was the transition to cLBP at 6 months. We built predictive models within groups using the minimum redundancy maximum relevance algorithm to identify key predictors, focusing on models discrimination and calibration. Risks of transition were 35.8%, 44.3%, and 45.6%, for the nonchronic, acute, and new episode groups, respectively. Pain intensity, disability, and depression emerged as consistent predictors across definitions. The acute and new episode models, but not the nonchronic , were considered clinically useful (area under the receiver operating characteristic curve > 0.7), with the latter displaying better calibration and increased performance after adjustment to pain duration. These findings highlight the importance of standardizing aLBP definitions to improve risk stratification and targeted early interventions. Clearer definitions can enhance predictive accuracy, ensuring more effective resource allocation and preventive strategies for individuals at risk of developing chronic pain.

Keywords: Acute low back pain; Acute low back pain definition; Chronic low back pain; Prognostic risk factors; Risk of transition; Transition to chronic pain.

Figure 1.

Flowchart of enrollment and follow-up in the Quebec Low Back Pain Study (QLBPS). Participants with acute low back pain (aLBP) not meeting the NIH criteria for chronic LBP (cLBP) 6 months after baseline were reclassified as having nonchronic LBP (non-cLBP). The hatched square indicates the dataset used in this study.

Figure 2.

Diagram of Quebec Low Back Pain Study (QLBPS) participants with acute low back pain (aLBP) at baseline assigned to the nonchronic, acute, or new episode groups (rectangles) and to the nonchronic only, acute only, or new episode only groups (circles).

Figure 3.

Predictive models of the transition of acute low back pain (aLBP) to chronic LBP (cLBP) in participants assigned to the nonchronic, acute, or new episode groups and their respective area under the receiver operating characteristic curve (AUROC) and calibration curve (orange line; shaded area around it represents the confidence interval).