National prevalence of gout derived from administrative health data in Aotearoa New Zealand

Objective. Previous small studies in Aotearoa New Zealand have indicated a high prevalence of gout. This study sought to determine the prevalence of gout in the entire Aotearoa New Zealand population using national-level health data sets. Methods. We used hospitalization and drug dispensing claims for allopurinol and colchicine for the entire Aotearoa New Zealand population from the Aotearoa New Zealand Health Tracker (ANZHT) to estimate the prevalence of gout in 2009, stratified by age, gender, ethnicity and socio-economic status (n = 4 295 296). Results were compared with those obtained from an independent large primary care data set (HealthStat, n = 555 313). Results. The all-ages crude prevalence of diagnosed gout in the ANZHT population was 2.69%. A similar prevalence of 2.89% was observed in the HealthStat population standardized to the ANZHT population for age, gender, ethnicity and deprivation. Analysis of the ANZHT population showed that gout was more common in M (a) over bar ori and Pacific people [relative risk (RR) 3.11 and 3.59, respectively], in males (RR 3.58), in those living in the most socio-economically deprived areas (RR 1.41) and in those aged > 65 years (RR > 40) (P-value for all < 0.0001). The prevalence of gout in elderly M (a) over bar ori and Pacific men was particularly high at > 25%. Conclusion. Applying algorithms to national administrative data sets provides a readily available method for estimating the prevalence of a chronic condition such as gout, where diagnosis and drug treatment are relatively specific for this disease. We have demonstrated high gout prevalence in the entire Aotearoa New Zealand population, particularly among M (a) over bar ori and Pacific people.