Low back pain is the leading cause of disability in the United States. Although it's generally believed acute low back pain resolves in a few months, recent evidence suggests that up to about half of people with this condition transition to chronic low back pain. Estimates of this rate of transition vary widely, partly because of a lack of standardized definitions. In a cohort study conducted alongside a multisite randomized trial, researchers investigated whether the transition from acute to chronic low back pain is associated with risk strata (as defined by a standardized prognostic tool), patient characteristics, and early exposure to guideline nonconcordant care.

The researchers prospectively enrolled adults who were seen in primary care practices for acute low back pain. They administered the Subgroups for Targeted Treatment (STarT) Back tool at baseline, stratifying patients by risk (low, medium, high) of developing chronic low back pain. Low back pain-related processes of care provided by a primary care clinician within 21 days of a patient's index visit were extracted from the electronic health record. These processes of care were codified into three categories: receipt of opioids, imaging, and subspecialty referral. Each was categorized as concordant or nonconcordant with international low back pain guidelines.

Of the 5,233 patients included in the final cohort, 34% were found to be at low risk, 41% at medium risk, and 25% at high risk for developing chronic low back pain. Overall, the rate of transition from acute to chronic low back pain was 32% at six months. In a multivariable model, risk strata using the STarT Back tool were positively associated with transition to chronic low back pain. Compared with low-risk patients, high-risk patients had 2.45 times higher adjusted odds of developing chronic low back pain; for medium-risk patients, odds were 1.59 times higher. Factors associated with the development of chronic low back pain included body mass index, smoking status, baseline disability, and psychological comorbidities. Patients exposed to one, two, or three nonconcordant processes of care were 1.39, 1.88, and 2.16 times more likely to develop chronic low back pain, respectively, compared with patients who had no exposure to these processes of care.