Stratification of spine patients based on self-reported clinical symptom classes: Evaluation of long-term outcomes and subsequent interventions

Background: Prior work by our group developed a stratification tool based on four PROMIS domains for patients with low back pain (LBP). Our study aimed to evaluate the ability of our previously developed symptom classes to predict long-term outcomes, and determine whether there were differential treatment effects by intervention. Methods: This was a retrospective cohort study of adult patients with LBP seen in spine clinics in a large health system between November 14, 2018 and May 14, 2019 who completed patient-reported outcomes as part of routine care at baseline and again at 12-months follow-up. Latent class analysis identified symptom classes based on PROMIS domain scores (physical function, pain interference, social role satisfaction, and fatigue) that were ≥1 standard deviation worse (meaningfully worse) than the general population. The ability of the profiles to predict long-term outcomes at 12-months was evaluated through multivariable models. Differences in outcomes by subsequent treatments (physical therapy, specialist visits, injections, and surgery) were investigated. Results: There were 3,236 adult patients (average age 61.1 ± 14.2, 55.4% female) included in the study with three distinct classes identified: mild symptoms (n = 986, 30.5%), mixed (n = 798, 24.7%) with poor scores on physical function and pain interference but better scores on other domains, and significant symptoms (n = 1,452, 44.9%). The classes were significantly associated with long-term outcomes, with patients with significant symptoms improving the most across all domains. Utilization differed across classes, with the mixed symptom class receiving more PT and injections and significant symptom class receiving more surgeries and specialist visits. Conclusions: Patients with LBP have distinct clinical symptom classes which could be utilized to stratify patients into groups based on risk of future disability. These symptom classes can also be used to provide estimates of the effectiveness of different interventions, further increasing the clinical utility of these classes in standard care.