Stratification of spine patients based on self-reported clinical symptom classes

Abstract

Background context: Improving prognostic stratification for patients with low back pain (LBP) outside of a primary care setting has been identified as an important area for further research.

Purpose: Our study aimed to identify clinical symptom classes of patients presenting to a spine clinic based on 4 Patient Reported Outcome Measurement Information System (PROMIS) domains and evaluate demographic and clinical differences across classes.

Study design: An observational cross-sectional study of patients seen in spine centers at a large health system.

Patient sample: Adult patients with LBP seen in a spine center between November 14, 2018 and May 14, 2019 who completed patient-reported outcomes as part of routine care.

Outcome measures: PROMIS physical function, pain interference, satisfaction with social roles and activities, and fatigue.

Methods: Latent class analysis identified symptom classes based on PROMIS domain scores ≥1 standard deviation worse (meaningfully worse) than the general population. A multivariable multinomial logistic regression model was constructed to evaluate differences in symptom classes based on demographics and socioeconomic characteristics. Lastly, the ability of the profiles to discriminate across levels of disability, based on the modified Oswestry Disability Questionnaire (ODI), was evaluated.

Results: There were 7,144 adult patients included in the study who visited spine clinics for a primary complaint of LBP and completed all 4 PROMIS domains (age 58.7±15.9, 54% female). Three distinct classes were identified. Class 1 ("Significant Symptoms," n=3238) had PROMIS scores that were meaningfully worse than the population average for all domains. Class 2 ("Mixed Symptoms," n=1366) had meaningfully worse scores on physical function and pain interference but average scores on other domains. Class 3 ("Mild Symptoms," n=2540) had average scores across all domains. Compared to patients in Class 3, those in Class 2 were more likely older, and those in Classes 1 and 2 were more likely to be divorced, have lower household income, and no employment. Level of disability was significantly different across each class (average (SD) ODI for Classes 1-3: 53.4 (14.3), 39.9 (12.5), 22.9 (12.1), p<.01).

Conclusions: Patients presenting to specialty clinics for LBP demonstrate distinct clinical symptom classes which could be utilized to inform specific symptom-based treatment. Future research should evaluate the ability of these classes to predict long-term disability.

Keywords: Latent class analysis; Low back pain; PROMIS; Patient-reported outcomes; Stratification; Symptom clusters.