Supplementary Material for: Pain Intensity and Pain Interference in Older Adults: Role of Gender, Obesity and High-Sensitivity C-Reactive Protein

Background: Among older adults, pain intensity and pain interference are more common in women than men and associated with obesity and inflammatory markers. Objective: We examined whether the obesity and pain relationship is mediated by the high-sensitivity C-reactive protein (hsCRP), a nonspecific marker of systemic inflammation, and whether this relationship differs by sex. Methods: Items from Medical Outcomes Study Short Form-36 were used to measure pain intensity and pain interference in daily life. Ordinal logistic regression was used to assess the cross-sectional association among body mass index (BMI), hsCRP levels, pain intensity and pain interference using gender-stratified models adjusted for demographic variables. Results: Participants included 667 community-residing adults over the age of 70 years, free of dementia, enrolled in the Einstein Aging Study (EAS). In women (n = 410), pain intensity was associated with obesity [BMI ≥30 vs. normal, odds ratio (OR) = 2.29, 95% confidence interval (CI) 1.43-3.68] and higher hsCRP (OR = 1.28, 95% CI 1.08-1.51). In a model with obesity and hsCRP, both remained significant, but the association between hsCRP and pain intensity was somewhat attenuated. Obesity (OR = 3.04, 95% CI 1.81-5.11) and higher hsCRP levels (OR = 1.30, 95% CI 1.08-1.56) were also independently associated with greater pain interference in women. After adjustment for pain intensity and BMI, hsCRP was no longer associated with pain interference in women. Greater pain intensity and being overweight or obese continued to be significantly associated with pain interference in women. In men (n = 257), obesity and hsCRP were not associated with pain intensity or pain interference. Conclusions: In women, the relationship between obesity and higher levels of pain intensity or interference may be accounted for by factors related to hsCRP.