Background/Purpose: Chronic pain is a critical health problem among Operations Enduring Freedom/Operation Iraqi Freedom service members. The deleterious impact of chronic pain on quality of life and function are well described in the literature. However, little is known about the relationship between the number of chronically painful body sites and pain severity and disability-associated outcomes. In this secondary data analysis of a randomized clinical trial of a stepped-care intervention for OEF/OIF veterans with chronic musculoskeletal pain, we evaluated the association between the number of chronically painful body sites with long term pain-related outcomes.   

Methods: We analyzed 222 subjects (92% of the original cohort) with available data at baseline and at the last follow-up visit (i.e., month 9). Consistent with the 2010 ACR criteria for fibromyalgia*, we dichotomized the number of chronically painful body sites (primary independent variable) as ≥3 (yes or no).  We measured baseline to month 9 changes on our two primary outcomes: 1) pain intensity (as measured by Graded Chronic Pain Scale/GCPS), and 2) pain-related disability (as measured by Brief Pain Interference (BPI). Secondary outcomes included changes in SF-36 Physical Component Summary (SF-36 PCS), depression (PHQ-9) and anxiety (GAD-7) measures. We used multiple linear regression analyses to determine the relationships of the number of painful body sites with the outcome measures.

Results: Characteristics of the 222 subjects at study entry: mean age (SD)=37.3 (10.2) years; male=88%; whites= 78%; married=57%; # comorbidity=1.0 (1.0); GCPS pain intensity=65.6 (13.7); BPI pain interference=5.3 (2.2); SF-36 PCS=37.6 (7.2); PHQ-9=10.8 (5.8); GAD-7=8.5 (5.2); # of pain-related medications=1.7 (1.2); # of physical symptoms=2.0 (1.8); and 69% (n=154) had ≥ 3 painful body sites.  

Table 1.

Age, gender, race, and marital status were included on each of the multivariate models but were all non-significant (p>0.10)

Neither the number of painful sites nor the treatment group assignment was significantly associated with changes in PHQ-depression and GAD-7 anxiety. Only the number of comorbid medical conditions was associated with changes in depression (estimate (SE) =-0.9 (0.4), p=0.0184) and anxiety (estimate (SE) =-0.7 (0.3), p=0.0179).

Conclusion: Compared to veterans with <3 painful body sites, veterans with ≥3 painful body sites improved significantly less during the 9 months of the trial. Our findings suggest more aggressive treatment interventions are needed in this population of veterans with multiple pain sites.