Background/Purpose: There are no published studies on correlates of inflammatory back pain (IBP) based on a large-scale nationally representative sample. In the present study, we examine the demographic and clinical features that are associated with IBP among adults with chronic back pain who participated in the US National Health and Nutrition Examination Survey (NHANES) 2009-2010.

Methods: NHANES 2009-2010 surveyed 5106 adults (ages: 20 to 69), representative of the US population. The study participants were interviewed and examined by trained personnel to obtain demographic and clinical data.  A detailed questionnaire focused on back pain and associated features was administered.  Chronic back pain was defined as back discomfort present on most days for more than 3 months.  Based on this definition, 980 (19.2%) had chronic back pain. Two published sets of criteria for IBP were utilized to identify participants with IBP in the chronic back pain group.  Specifically, the outcome variable was IBP as defined by presence of four (out of five) European Spondyloarthritis Study Group (ESSG) or two (out of four) 2006 Berlin Criteria.  The investigated independent variables included a comprehensive list of demographic features including age, gender, ethnicity, education, income, exercise habits, body mass index (BMI), alcohol use, and smoking status. In addition, laboratory and clinical features including C-reactive protein, presence of diabetes, hepatitis C, arthritis, uveitis, inflammatory bowel disease, psoriasis, rapid response to NSAIDs, and heel pain were also investigated. Specifically, presence of arthritis was determined by affirmative response to the question “has a doctor ever told you that you had arthritis”.  Obesity was defined as BMI >30.  Among patients with chronic back pain, the association of demographic and clinical features with IBP was assessed with weighted logistical regression analysis in univariable and multivariable models in order to identify the independent correlates of IBP.

Results: First, correlates of IBP according to the ESSG criteria were examined.  Among participants with chronic back pain, absence of morbid obesity (OR: 1.86, p<0.001), presence of arthritis diagnosed by a physician (OR: 1.6, p=0.021), rapid response to NSAIDs (OR: 1.6, p=0.032), younger age (20-49 versus 50-65 age group, OR: 3.68, p<0.001) were independent correlates of IBP in the multivariable model.  Next, correlates of IBP according to Berlin Criteria were investigated.  For this purpose, participants over 50 year of age were excluded because the Berlin Criteria are not applicable to this age group.  The presence of arthritis diagnosed by a physician (OR=1.7, p=0.039), psoriatic skin disease (OR=3.2, p=0.04), current smoking (OR: 1.8, p=0.017), and lower education level (high school diploma or less versus the rest, OR=1.6, p=0.04) were independently associated with IBP in the multivariable model.  

Conclusion:  Certain demographic features including younger age, lower BMI, lower educational level, and current smoking, as well as several clinical characteristics, specifically arthritis, psoriasis, and rapid response to NSAIDs are associated with IBP in adults with chronic back pain in the US population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/correlates-of-inflammatory-back-pain-in-a-nationally-representative-sample-of-the-us-population/