Pain Intensity as a Lagging Indicator of Patient Improvement: Longitudinal Relationships With Sleep, Psychiatric Distress, and Function in Multidisciplinary Care.

Despite a common assumption that reductions in chronic pain intensity must precede improvements in other pain-relevant domains, there has been limited empirical inquiry into the temporal ordering of improvements in chronic pain treatment. Cross-lagged models using retrospective clinical data examined relationships between average pain intensity and symptoms of psychological distress, difficulties with sleep initiation and maintenance, and disability in 666 treatment-seeking patients with chronic pain who demonstrated improvement in pain intensity (≥1-point reduction on 0-10 numeric rating scale) over a 1-year span. Results indicated that decreased difficulties with sleep initiation, depressive and anxious symptoms, and disability predicted later improvement in pain intensity, whereas greater pain intensity predicted only later difficulties in sleep initiation and maintenance. A combined lagged model highlighted fewer baseline symptoms of post-traumatic stress disorder and lower levels of baseline disability as significant predictors of later improvements in pain. Overall, our results indicate that reductions in pain intensity may not be the first factors to change in effective chronic pain management. The current findings should be replicated using prospective studies utilizing structured approaches to maximize data capture, as well as uniform interventional approaches to permit greater inferences regarding causal and temporal aspects of the model. PERSPECTIVE: This study demonstrates that pain intensity scores are not robust predictors of psychosocial outcomes longitudinally. Instead, other factors such as sleep initiation, psychological distress and disability appear to be important targets for intervention that may promote effective pain reduction.