Association between idiopathic intracranial hypertension and risk of cardiovascular diseases in women in the United Kingdom

Importance: Cardiovascular disease (CVD) risk has not been previously evaluated in a large matched cohort study in idiopathic intracranial hypertension (IIH).

Objectives: To estimate the risk of composite cardiovascular events, heart failure, ischemic heart disease, stroke/transient ischemic attack (TIA), type 2 diabetes, and hypertension in women with idiopathic intracranial hypertension and compare it with the risk in women, matched on body mass index (BMI) and age, without the condition; and to evaluate the prevalence and incidence of IIH.

Design, Setting, and Participants: This population-based matched controlled cohort study used 28 years of data, from January 1, 1990, to January 17, 2018, from The Health Improvement Network (THIN), an anonymized, nationally representative electronic medical records database in the United Kingdom. All female patients aged 16 years or older were eligible for inclusion. Female patients with IIH (n = 2760) were included and randomly matched with up to 10 control patients (n = 27125) by BMI and age.

Main Outcomes and Measures: Adjusted hazard ratios (aHRs) of cardiovascular outcomes were calculated using Cox regression models. The primary outcome was a composite of any CVD (heart failure, ischemic heart disease, and stroke/TIA), and the secondary outcomes were each CVD outcome, type 2 diabetes, and hypertension.

Results: In total, 2760 women with IIH and 27125 women without IIH were included. Age and BMI were similar between the 2 groups, with a median (interquartile range) age of 32.1 (25.6-42.0) years in the exposed group and 32.1 (25.7-42.1) years in the control group; in the exposed group 1728 women (62.6%) were obese, and in the control group 16514 women (60.9%) were obese. Higher absolute risks for all cardiovascular outcomes were observed in women with IIH compared with control patients. The aHRs were as follows: composite cardiovascular events, 2.10 (95% CI, 1.61-2.74; P <.001); heart failure, 1.97 (95% CI, 1.16-3.37; P =.01); ischemic heart disease, 1.94 (95% CI, 1.27-2.94; P =.002); stroke/TIA, 2.27 (95% CI, 1.61-3.21; P <.001); type 2 diabetes, 1.30 (95% CI, 1.07-1.57; P =.009); and hypertension, 1.55 (95% CI, 1.30-1.84; P <.001). The incidence of IIH in female patients more than tripled between 2005 and 2017, from 2.5 to 9.3 per 100000 person-years. Similarly, IIH prevalence increased in the same period, from 26 to 79 per 100000 women. Incidence increased markedly with BMI higher than 30.

Conclusions and Relevance: Idiopathic intracranial hypertension in women appeared to be associated with a 2-fold increase in CVD risk; change in patient care to modify risk factors for CVD may reduce long-term morbidity for women with IIH and warrants further evaluation.