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A diagnosis of incident or new chronic pain may be twice as likely in patients with vs without gout, according to a study published in Clinical Rheumatology.
As the most frequently diagnosed type of inflammatory arthritis, gout often occurs as intermittent acute flares. Gout may also represent an under-recognized correlate of non-flare chronic pain. Investigators sought to determine whether there was an association between gout and chronic pain.
A 5% random sample derived from United States Medicare claims data filed between 2006 and 2012 was examined. In this study, the presence of gout at baseline was the independent variable, and the occurrence of new chronic pain was the dependent variable and primary outcome. Crude incidence rates for new chronic pain diagnoses were calculated and multivariable Cox regression analysis was performed, adjusting for demographics, comorbidity (using the Charlson-Romano index), and cardiovascular or gout medication use (model 1). Sensitivity analyses were conducted to account for the presence of grouped (model 2) and individual (model 3) comorbidities.
Of 1,321,521 eligible participants (mean age, 75.2 years; 54.7% women; 85.5% white), 424,518 individuals (32.1%) were diagnosed with chronic pain at follow-up, leading to crude incidence rates of 158.1 and 64.5 per 1000 person-years in patients with and without gout, respectively. In model 1, the risk for new chronic pain in patients with gout was twice as high as in patients without gout (hazard ratio [HR], 2.02; 95% CI 1.98-2.05; P <.0001). In sensitivity analyses, the risk for chronic pain was slightly lower but still elevated with vs without gout in both model 2 (HR, 1.96; 95% CI, 1.93-1.99; P <.0001) and model 3 (HR, 1.77; 95% CI, 1.74-1.80; P <.0001).
Subgroup analyses revealed no significant differences associated with gender or race. In the oldest participants (ie, age >85 years) with gout, there was a minor reduction in chronic pain risk (HR, 1.75; 95% CI, 1.67-1.85; P <.0001) compared with younger individuals with gout. In model 1, the use of allopurinol (HR, 0.79; 95% CI, 0.77-0.82; P <.0001) or febuxostat (HR, 0.72; 95% CI, 0.56-0.92; P =.009) was associated with a lower risk for incident chronic pain in individuals with gout.
Study strengths include a large sample size, representative population, robust results, and focus on a clinically relevant question. Study limitations include a potential misclassification bias, non-generalizability to individuals age <65, the use of a non-specific diagnostic approach, and underestimation of obesity prevalence.
“Efforts must be made to optimize gout control, so that chronic pain can be avoided as a long-term sequelae of gout and when present, treated early and appropriately,” noted the authors.
Reference
Singh JA, Cleveland JD. Gout and chronic pain in older adults: a Medicare claims study. Clin Rheumatol. March 2019. doi:10.1007/s10067-019-04526-0
