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

Abstract

Background ContextAlthough back pain is common among older adults, there is relatively little research on the course of back pain in this age group. PurposeOur 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/SettingThis study used a predictive model using data from a prospective, observational cohort from a primary care setting. Patient SampleThe study included patients aged ≥65 years at the time of new primary care visits for back pain. Outcome MeasuresSelf-reported 2-year disability (Roland-Morris Disability Questionnaire [RDQ]) and back pain (0–10 numerical rating scale [NRS]). MethodsWe 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. ResultsOf 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. ConclusionsBaseline patient factors were more important than early interventions in explaining disability and pain after 2 years.