Background Recent reviews on the epidemiology of gout in the general population report a prevalence between 1 and 2%, and suggest an increase in recent years. Some concerns were raised on the internal and external validity of published studies (1-3). Moreover, the variability in the study samples and the use of different approaches to classify gout hampers comparability between studies.
Objectives To systematically review the literature on prevalence and incidence of gout, and to explore factors contributing to the heterogeneity among studies.
Methods Pubmed, Embase and Web of Science were systematically searched for primary studies on the prevalence and incidence of gout in the general population. Included studies were assessed for risk of bias. Prevalence rates were pooled using a random-effects model and were adjusted for a series of clinical and methodological study characteristics in a meta-regression analysis using the mixed-effects model. Classification criterion, the key study characteristic, was subdivided in 7 categories (self-reported diagnosis, self-reported symptoms, self-reported diagnosis with confirmation, self-reported symptoms with confirmation, examination by a health professional, general practitioner medical records and hospital medical records).
Results 77 articles were included, of which 71 reported the prevalence and 12 the incidence of gout. Pooled prevalence was 0.78% (95% CI 0.55; 1.05) with a 95% prediction interval of 0.00-6.84%. The I² statistic indicated a high level of heterogeneity (99.95%). Risk of bias accounted for only 0.65% of the total heterogeneity. In the multivariable analysis, gender (P=0.001), continent (P <0.001), and classification criterion (P <0.001) were significantly associated with gout prevalence, whereas publication year, mean age, setting and prevalence type were not. Of the classification criteria, examination by a health professional resulted in the lowest prevalence. The full model accounted for 76% of the heterogeneity.
With regard to the incidence of gout, the small number of articles and high heterogeneity hampered a meta-regression analysis. The incidence per person-years ranged from 0.06/1000 to 2.68/1000 in the total population (≥15 year). When inspecting data carefully, higher incidences were observed in males and in studies that had a longer patient follow-up. 6 articles compared the incidence of gout across years and did not find evidence for a secular trend in gout incidence.
Conclusions The large variation in the prevalence data on gout in the population is not only explained by gender, and by continent where the study was performed, but also by the classification criteria used. There was no support for an increase in prevalence or incidence of gout in recent years.
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Disclosure of Interest None Declared