Long-term outcomes of a large, prospective observational cohort of older adults with back pain

Abstract

Background context: Although back pain is common among older adults, there is relatively little research on the course of back pain in this age group.

Purpose: Our primary goals were to report 2-year outcomes of older adults initiating primary care for back pain and to examine the relative importance of patient factors versus medical interventions in predicting 2-year disability and pain.

Study design/setting: This study used a predictive model using data from a prospective, observational cohort from a primary care setting.

Patient sample: The study included patients aged ≥65 years at the time of new primary care visits for back pain.

Outcome measures: Self-reported 2-year disability (Roland-Morris Disability Questionnaire [RDQ]) and back pain (0-10 numerical rating scale [NRS]).

Methods: We developed our models using a machine learning least absolute shrinkage and selection operator approach. We evaluated the predictive value of baseline characteristics and the incremental value of interventions that occurred between 0 and 90 days, and the change in patient disability and pain from 0 to 90 days. Limitations included confounding by indication and unmeasured confounding.

Results: Of 4,665 patients (89%) with follow-up, both RDQ (from mean 9.6 [95% confidence interval {CI} 9.4-9.7] to mean 8.3 [95% CI 8.0-8.5]) and back pain NRS (from mean 5.0 [95% CI 4.9-5.1] to mean 3.5 [95% CI 3.4-3.6]) scores improved slightly. Only 16% (15%-18%) reported no back pain-related disability or back pain at 2 years after initial visits. Regression model parameters explained 40% of the variation (R²) in 2-year RDQ scores, and the addition of 0- to 3-month change in RDQ score and pain improved prediction (R²=51%). The most consistent predictors of 2-year RDQ scores and back pain NRS scores were 0- to 90-day change in each respective outcome and patient confidence in improvement. Patients experienced 50% and 43% improvement in back pain and disability, respectively, 2 years after their initial visit. However, fewer than 20% of patients had complete resolution of their back pain and disability at that time.

Conclusions: Baseline patient factors were more important than early interventions in explaining disability and pain after 2 years.

Keywords: Back pain; Disability; Functional status; Older adults; Predictive modeling; Prognosis.