Giant cell arteritis (GCA) as a risk factor for seizures: a cohort study

Objectives: The objective of this study was to assess the risk of seizures in Giant Cell Arteritis (GCA) patients in a large cohort of Israeli subjects, in comparison to matched controls. Methods: Patients diagnosed with GCA between 2002 and 2017 were included. Controls were matched based on sex, age, socioeconomic status, country of birth, diabetes mellitus, and hypertension in a 4:1 ratio. Patients with seizure records prior to the study period were excluded. Hazard ratios for seizures was obtained by cox regression models. Results: The study cohort was composed by 8,103 GCA patients and 32,412 matched controls. The GCA group included 5,535 women (68%), 2,644 patients born in Israel (33%), and 2,888 patients with low socioeconomic status (36%). The median age of this group was 71. During the followed cumulative person-years of 54,641 and 222,537 in the GCA and control group, respectively, 15.92 cases per 10,000 person-years was found in the GCA group, compared to 9.62 per 10,000 person-years in the controls. GCA was associated with seizures in the unadjusted (HR = 1.66, 95% CI [1.29 to 2.13]) and adjusted (HR = 1.67, 95% CI [1.3 to 2.14]) models. GCA was also associated with seizures after controlling for strokes (HR = 1.55, 95% CI [1.16 to 2.07]). Conclusion: According to this study, individuals with GCA are at a higher risk of developing seizures when compared to the general population. This increased risk is independent of their predisposition for stroke. One proposed mechanism is that the GCA pro-inflammatory state may decrease the neuronal threshold for depolarization.