Trajectories of symptoms and function in older adults with low back disorders

Study Design. Prospective cohort study. Objective. To determine whether there are distinct trajectories of back pain and function among older adults and to identify characteristics that distinguish among patients with substantially different prognoses. Summary of Background Data. Although the differential diagnosis and course of low back pain among older adults may differ from middle-aged adults, there is little evidence. Better understanding variability in recovery among older adults may help target patients for more intensive clinical interventions, plan resource use, and design clinical studies of more homogeneous patient groups. Methods. Patients aged 65 years or older with a new episode of care for back pain were recruited at 3 geographically diverse sites. Patients completed pain intensity and Roland-Morris Disability measures at baseline and 3, 6, and 12 months later. We used latent class analysis to identify distinct trajectories of pain and function and then logistic regression to identify predictors of membership in the improving trajectories. Results. There were 3929 participants who completed outcome measures at every follow-up interval. Latent class analysis identified subgroups with low, intermediate, or high pain or disability scores who remained relatively stable over time. However, small subgroups showed dramatic improvement from baseline to 1 year (17% with major improvement in Roland score, pain intensity, or both). Shorter pain duration, higher patient confidence in improvement, and fewer comorbid conditions at baseline were each associated independently with favorable prognosis. Conclusion. Although most patients remained relatively stable over a year, latent class analysis identified small groups with major improvement in pain, function, or both. This technique may, therefore, be useful for studying back pain prognosis. Our results should help assemble more prognostically homogeneous groups for research, and the technique may help identify subgroups of patients with uniquely successful responses to investigational interventions.