Hormonal Contraception and IIH Risk: New Data

Use of hormonal contraception — regardless of type or delivery method — was not associated with a significant increased risk for idiopathic intracranial hypertension (IIH) in women of reproductive age, a new study showed. The systematic review and meta-analysis is the first to show no link between IIH prevalence and the use of hormonal birth control, including oral contraceptives, intrauterine devices (IUDs), hormonal injections, or implants. “The findings of this study provide reassurance to the treating physicians that hormonal contraception need not be considered a contraindication in IIH,” investigator Arun N.E. Sundaram, MD, Division of Neurology, University of Toronto, Ontario, Canada, told Medscape Medical News. The study was published online on March 25 in Neurology. ‘Longstanding Concern’ Early case reports and small observational studies have suggested a possible temporal relationship between the start of hormonal contraception among women of reproductive age and subsequent IIH diagnosis, including reports involving oral contraceptive pills and IUDs. “The use of hormonal contraception in patients with IIH has been controversial and a longstanding concern,” Sundaram said. “Patients with IIH have been receiving conflicting information from physicians regarding the use of hormones, but most of the available literature did not largely support hormonal contraception as a substantial risk factor in IIH,” he added. To investigate further, researchers conducted a systematic review of observational that compared hormonal contraceptive use among women with and without IIH. The final analysis included 10 case-control studies and three cohort studies with 5351 women with IIH and 669,260 control participants (mean age, 33.3 years). Hormonal contraceptives included oral contraceptive pills, IUDs, vaginal rings, injectable agents such as medroxyprogesterone acetate, subdermal implants, and transdermal patches. What the Numbers Revealed? The use of any hormonal contraception was reported by 25.2% of the IIH group vs 19.2% of the control group. The risk for IIH was not statistically different between groups (odds ratio, 0.93; P = .60). Subgroup analyses by contraception type also showed no significant associations. Results were consistent across multiple sensitivity analyses, including those restricted to more recent studies and those using standardized IIH diagnostic criteria. Nine of the included studies found no significant association between hormonal contraception use and IIH prevalence; three found lower odds of hormonal contraception use among individuals with IIH than among control individuals; and one found higher odds, specifically for the levonorgestrel IUD. However, this single finding did not persist in the meta-analysis, which found no association between IUD use and IIH prevalence across five studies. Study limitations included low to very low certainty of evidence and considerable heterogeneity across studies, compounded by incomplete data on important factors such as obesity and variability in how contraceptive exposure was defined. Reassuring Findings The current findings should reassure patients and clinicians about the low risk for oral contraceptives and IUDs among women with IIH, Andrew G. Lee, MD, a neuro-ophthalmologist and professor of neurology, neurosurgery, and ophthalmology at Weill Cornell Medical College in New York City, told Medscape Medical News. The role of hormonal contraception in IIH has been overestimated in clinical practice, Lee said, likely due to clinician bias. “Doctors have a bias and one of their biases is they like to blame something and have a diagnosis. We hate that diagnosis ‘idiopathic.’ However, IIH remains idiopathic to this day,” said Lee, who was not part of the study. The results also highlight the need to check for other causes when IIH is suspected, Lee said. The only scenario in which hormonal therapy may be causal is if a patient has a cerebral venous sinus thrombosis (CVST) diagnosis, a rare clot that can mimic or cause increased intracranial pressure. Estrogen-containing hormonal contraception is a known risk factor for CVST, which is distinct from IIH, said Lee, who also is chair of ophthalmology at Blanton Eye Institute, Houston Methodist Hospital, Houston. “Patients with suspected IIH should have an MRI and a [magnetic resonance] venogram to exclude venous sinus thrombosis,” Lee suggested. Future research should explore prothrombotic conditions that could increase susceptibility to IIH in the context of hormonal contraception, he added. “The bottom line is that given the limited quality of available evidence and considerable heterogeneity in the existing studies, future large-scale, well-designed studies, particularly in diverse patient populations will be necessary to validate these findings,” he said. Sundaram and Lee reported having no relevant financial relationships.