A Nationwide Cohort Study of Actinic Keratosis in Taiwan

Background: Incidence of actinic keratosis (AKs) and nonmelanoma skin cancer appears to be increasing worldwide due to increasing levels of ultraviolet radiation, lifestyle changes, and an aging population. However, there is no population-based study focusing on AKs among Asian population. We aimed to investigate the incidence, the treatment pattern, the medical utilization and the risk of malignant neoplasm of the AKs patients in Taiwan. Methods: We conducted a retrospective cohort study to investigate patients with AKs from 2003 to 2011 by using the National Health Insurance Research Database (NHIRD). The inclusion criteria were patients who had at least two outpatient visits or one hospital admission of AK identified by dermatologist from 2004 to 2011. There were 35,933 patients with AKs (elderly [aged ≥65 years]: n = 17,004; non-elderly [aged