The risk of polymyalgia rheumatica in older adults with gout: a Medicare claims study.

OBJECTIVE

In the absence of previous studies, the objective was to assess whether gout is associated with a lower risk of PMR.

METHODS

We used the 5% Medicare sample to assess whether gout in adults 65 years or older increases the risk of incident PMR. The main multivariable-adjusted model included age, gender, race, Charlson-Romano co-morbidity score, the use of medications for cardiovascular diseases (statins, β-blockers, diuretics, angiotensin-converting enzyme inhibitors) and gout (allopurinol, febuxostat). Hazard ratios and 95% CI were calculated.

RESULTS

There were 11 744 cases of incident PMR, with crude incidence rates of PMR of 289/100 000 person-years in patients with gout and 109/100 000 person-years in patients without gout. People with incident PMR had a mean duration of gout of 2.2 years before PMR diagnosis (s.d., 1.6; median, 1.8; interquartile range, 0.8, 3.2). Multivariable-adjusted analyses showed that gout was associated with PMR with a hazard ratio of 2.45 (95% CI, 2.28, 2.64; P < 0.0001). Older age, female gender, White race and higher co-morbidity index were associated with a higher hazard of PMR. Sensitivity analyses that substituted continuous Charlson-Romano co-morbidity score with categorized score or individual co-morbidities (plus hypertension, hyperlipidaemia and coronary artery disease) confirmed the main findings with minimal attenuation of hazard ratio, 2.39 (95% CI, 2.22, 2.57; P < 0.0001) and 2.13 (95% CI, 1.98, 2.29; P < 0.0001), respectively.

CONCLUSION

Contrary to our hypothesis, gout was associated with >2-fold higher risk of incident PMR in older adults. Studies should explore whether inflammation or hyperuricaemia is the underlying mechanism for this association.