Our study is the first to examine, from a population‐based perspective, sex differences in the population characteristics, evaluation and treatment of gout. The differences between women and men with gout are striking, as the women are about a decade older, have more associated comorbidites and are more likely to be taking diuretics. Over the past 20 years there have been only four small studies specifically examining sex differences in clinical characteristics of gout, none of which were population based.2,3,17,21
Lally et al2
in 1986 compared the clinical cases of 23 women with gout with 75 men with crystal‐proven gout. As compared with the men, the women were older, more likely to be receiving diuretics and more often had renal insufficiency. Similarly, Puig et al3
in 1991 compared the clinical features of 37 women with gout with 2002 men with gout. Here again, the women developed gout at a later age, had more associated comorbidities and received diuretics more often. Both Meyers and Monteagudo17
and DeSouza et al21
examined the medical records of women and men with gout and found that women were more likely to have tophi or polyarticular disease at presentation and upper extremity joint involvement, suggesting potentially that in women the diagnosis of gout may be delayed or the condition may be confused with other forms of arthritis.
Our findings as well as those of others2,3,17,21
indicate that the risk factors for gout in women are different from those in men. For example, renal disease and receipt of diuretics, both of which predispose to gout, were more common in women. Current recommendations calling for the use of thiazide diuretics as the preferred treatment for hypertension11
may have important implications in terms of gout frequency, particularly among older women. Hypertension, also an independent risk factor for hyperuricaemia and gout, is more common in women >50 years than in men of the same age.16
It was surprising that after adjustment for age, comorbidities and use of diuretics, women were less likely to receive allopurinol than men. In addition, it was interesting that women in our study received glucocorticoids and narcotics more often than men, possibly suggesting they had more severe episodes, greater chronicity to their gout or intolerance to other gout treatments; however, these drugs are not specific for gout and could have been used for other conditions. Further investigation into the management of gout in women and men is needed to assess whether treatment differences reflect appropriate care based on differences in the clinical spectrum of gout.
As shown in our study, substantial proportions of people who initiate treatment with ULDs do not receive surveillance of serum urate levels after initiation of the drug. Interestingly, women were more likely than men to receive appropriate monitoring after controlling for age, comorbidities, gout treatments, number of ULD dispensings and health plan. Although beyond the scope of this study, potential reasons for these differences could include greater vigilance by doctors when treating women with gout owing to a greater number of associated comorbidities and associated drugs, more overall healthcare encounters by women resulting in greater opportunities for monitoring, or better adherence by women with physician recommendations. Because we cannot account for serum urate tests ordered but not carried out, it is not possible to separate physician non‐adherence with ordering a recommended laboratory test from patient non‐adherence with obtaining the test.
An important strength of this study is that it includes a large population of patients with two or more diagnoses of gout at least 30 days apart, thus increasing the likelihood that these people were truly considered to have gout by the treating doctor. In addition, the patient sample is derived from seven health plans across the USA and thus includes a diversity of people. Limitations include lack of validation of diagnostic and procedure claims data, although any bias that occurred would be non‐differential between women and men. In addition, we cannot verify that the drugs examined were prescribed for gout. We were unable to assess the clinical implications of adherence and non‐adherence with the recommended surveillance of serum urate levels in terms of provider response to serum urate levels, efficacy of urate‐lowering treatment and clinical outcomes. Lastly, our results may not be generalisable to other health plans or other systems of healthcare delivery. At a minimum, these results are probably generalisable to at least 1 in 4 (24.6%) residents in the USA who are enrolled in HMOs.22
In summary, this is the first population‐based study examining sex differences in gout epidemiology, evaluation and treatment. The characteristics of women and men with gout are strikingly different, suggesting different risk factors for the condition. Of note, women were less likely to receive allopurinol after controlling for confounders using multivariable logistic regression. Lastly, women with gout were also more likely to receive the recommended surveillance of serum urate levels within the first 6 months after ULD initiation. This work suggests further investigation into quality of care for gout to ensure that both women and men with gout receive the recommended evaluation and treatment.