Women who suffer from idiopathic intracranial hypertension (IIH) have twice the risk of heart conditions and stroke than those of the same age and body mass index (BMI) who do not have IIH, a study published in JAMA Neurology has found.
IIH is a debilitating condition in which the pressure around the brain is severely raised, causing disabling chronic headaches. It can also compress the optic nerve, causing permanent vision loss in 25% of those affected. It is most commonly seen in women with obesity in their 20’s and 30’s.
The population-based matched controlled cohort study, by Nicola J Adderley (University of Birmingham, Birmingham, UK) et al, aimed to estimate the risk of composite cardiovascular events, heart failure, ischaemic heart disease, stroke/transient ischaemic attack (TIA), type 2 diabetes, and hypertension in women with IIH and compare it with the risk in women, matched on BMI and age, without the condition. It also aimed to evaluate the prevalence and incidence of IIH.
Adderley et al compared GP patient records from The Health Improvement Network (THIN)—an anonymised, nationally representative electronic medical records database in the UK—from January 1990 to January 2018 for 2,760 women with IIH against a control group of 27,125 women who do not have IIH. All female patients aged ≥16 years were eligible for inclusion, and average age in each group studied was 32 years.
Adjusted hazard ratios (aHRs) of cardiovascular outcomes were calculated using Cox regression models. The primary outcome was a composite of any cardiovascular disease (CVD; heart failure, ischaemic heart disease and stroke/TIA), and the secondary outcomes were each CVD outcome, type 2 diabetes, and hypertension.
The researchers found that 1,728 women (62.6%) were obese in the exposed group, and 16,514 women (60.9%) were obese in the control group. Higher absolute risks for all cardiovascular outcomes were observed in women with IIH compared to control patients: aHRs were 2.1 (95% confidence interval [CI] 1.61–2.74, p<0.001) for composite cardiovascular events; 1.97 (95% CI 1.16–3.37, p=0.01) for heart failure; 1.94 (95% CI, 1.27–2.94, p=0.002) for ischaemic heart disease; 2.27 (95% CI 1.61–3.21, p<0.001) for stroke/TIA; 1.3 (95% CI 1.07–1.57, p=0.009) for type 2 diabetes; and 1.55 (95% CI 1.30–1.84, p< 0.001) for hypertension. They also found that the incidence of IIH in female patients more than tripled between 2005 and 2017—from 2.5 to 9.3 per 100,000 person–years. IIH prevalence also increased during the same time period, from 26 to 79 per 100,000 women. Incidence increased markedly with BMI >30.
Writing in JAMA: Neurology, the authors say: “Absolute risk for this young population was low but noteworthy, considering the young age of the sample and the relatively short median follow-up (approximately 3.5 years). The disease burden of IIH is growing, and its prevalence and incidence are rising annually and heightened in those with obesity.”
And, they add: “This current study has identified that an IIH diagnosis is statistically significantly associated with increased risk of composite cardiovascular events, heart failure, ischaemic heart disease, and stroke/TIA, independent of BMI. This finding is the first indication that morbidity in IIH may extend beyond the typically considered areas of visual loss and chronic headaches.”
The investigators point out that the underlying mechanisms of the increased cardiovascular risk in IIH are not established, and that it was observed despite matching to an obese control population. “This finding adds support to the concept that cardiovascular risk in IIH is not exclusively associated with obesity, and it points to a more complex disease characterised by systemic metabolic dysregulation.”
Adderley et al say that further evaluation of the association between weight modification and cardiovascular risk in IIH would be of interest. Changes to patient care to modify risk factors for CVD may reduce long-term morbidity for women with IIH, and also warrants further evaluation.