0650 Does pain related disability moderate the relationship between subjective insomnia and anxiety in comorbid fibromyalgia and insomnia?

Abstract

Introduction: Fibromyalgia is a chronic widespread pain condition with up to 90% of patients experiencing comorbid sleep disorders (e.g., insomnia) and up to 64% experiencing comorbid anxiety disorders. Past research has shown: 1) a bidirectional relationship between insomnia and anxiety, 2) associations between pain and insomnia and 3) associations between pain and anxiety. However, research has yet to explore the role of pain, specifically pain related disability, in moderating the association between insomnia and anxiety. The present study evaluated the moderating impact of self‐reported pain related disability on the relationship between subjective sleep variables and anxiety scores in adults with fibromyalgia and insomnia (FMI). Methods: Two‐hundred and nineteen adults with FMI (Mage=51.53, SD=1.89, 92.8% female) completed daily sleep diaries over fourteen days, the Pain Disability Index (PDI), and the State‐Trait Anxiety Inventory Form Y‐1 (STAI‐Y1) as part of the baseline for a larger randomized clinical trial (SPIN, NCT#02001077). Moderation analyses included STAI‐Y1 as the dependent variable, sleep variables averaged over 14 days (Sleep Onset Latency‐ SOL, Wake After Sleep Onset‐WASO, Total Sleep Time‐TST, Sleep Efficiency‐%SE) as independent variables, PDI as the moderator, and age and years of education as covariates. For moderation at significance levels of p<0.05, significance of simple slopes at high (1 SD above), average, and low (1 SD below) PDI scores were examined. Results: PDI moderated the relationship between SOL and STAI‐Y1 (B=0.0052, SE=0.0019, p=0.01, R2=0.04). At high PDI scores (but not average), higher SOL was associated with higher STAI‐Y1 scores (B=0.0748, SE=0.0310, p=0.02). At low PDI scores, higher SOL was associated with lower STAI‐Y1 scores (B=‐ 0.0844, SE=0.0453, p=0.06; trend). Conclusion: Results indicate that at higher levels of perceived pain related disability, greater difficulty falling asleep is associated with increased levels of anxiety in FMI. At lower levels of pain related disability though, difficulty falling asleep and anxiety levels may have an inverse relationship. This points to a possible complex interplay between sleep difficulties, pain related disabilities and anxiety in the FMI population. Future research is warranted to examine potential causal relationships between pain, sleep, and anxiety.