The impact of month and season on the incidence of giant cell arteritis: an Intelligent Research in Sight (IRIS) Registry analysis

Purpose Previous investigations into the relationship between season and the incidence of giant cell arteritis (GCA) have produced conflicting results. This study aimed to explore the impact of season and new diagnoses of GCA in a more definitive sense by employing the large dataset of the Intelligent Research in Sight (IRIS) database. Methods The IRIS Registry was queried to identify new cases of GCA from 2013 to 2021. Statistical analyses were performed to determine the significance of the relationship between the time of year and the incidence of GCA on regional and nationwide bases via Cochran’s Q statistical test. Results A total of 27,339 eyes with a new diagnosis of GCA were identified. Neither the month nor the season of the year correlated with the incidence of GCA, regardless of geographic location within the USA ( p > 0.05 for each variable). Conclusions In the USA, the incidence of GCA does not appear to vary by month or season. While this finding contradicts certain previous studies that identified a relationship, the cohort of patients identified from the IRIS Registry is much larger than that of previous investigations. Clinicians should be mindful of the possibility of GCA, regardless of the time of the year.