The Spatial Epidemiology of Patients Who Were Screened for and Diagnosed With Primary Aldosteronism in Southern Thailand

Background: In Thailand where biochemical testing for detection of primary aldosteronism (PA) is only available in a few tertiary centers, which may contribute to a delay in case detection. This study aimed to identify the geographic distribution of PA screening and diagnosis and its contributing epidemiologic and geographic factors in Southern Thailand. Method: Data of 688 patients who underwent PA screening between 2011–2017 were reviewed from the electronic database. The patients’ residences were extracted from the identification cards or the address recorded in the hospital system. The presence of an endocrinologist and the dominant religion in each province were recorded. The province, district and subdistrict of each patient were transformed to a 6-digit administrative area code corresponding with the global one (GADM(©)). A generalized log-linear model was used to identify predictors for individuals being screened. Results: Overall, the prevalence and crude incidence rates of PA in Southern Thailand were 15.6% and 1.66/1,000,000 person-years, respectively. The provinces located adjacent to the Andaman Sea had the highest incidences of PA (3.62–5.17 patients/1,000,000 person-years). Areas with the highest screening rates were located at and near Songkhla where the major tertiary medical center is located. A multivariate log-linear model demonstrated that the distance from the major tertiary center was the only predictive factor for screening while the availability of an endocrinologist and cultural differences were not. The chances of patients who lived in Songkhla, lived less than or more than 200 km from Songkhla to receive PA screening were 100% (reference), 82% (95% CI:0.69–0.97, p-value 0.03), and 66% (95% CI:0.55–0.78, p-value < 0.001), respectively. Conclusion: Geographic location was the main factor contributing to a delay in case detection for PA. A public health policy should be developed to mitigate the geographic barrier thus improving the ability of patients to access healthcare services. Further research relating to the underlying risk of the disease such as genetic transmission in populations with a high incidence of PA should be performed.