Objectives To quantify the hospital burden and health economic impact of Idiopathic Intracranial Hypertension.

Design Observational cohort study.

Subjects All those within England with a diagnosis of Idiopathic Intracranial Hypertension were included.

Methods Hospital Episode Statistics (HES) national data was extracted between 1 st January 2002 and 31 st December 2016. Those with secondary causes of raised intracranial pressure such as tumours, hydrocephalus and cerebral venous sinus thrombosis were excluded.

Results 23 182 new IIH cases were diagnosed. 52% resided in the most socially deprived areas. Incidence rose between 2002 to 2016 from 2.3 to 4.7 per 1 00 000 in the general population. Peak incidence occurred in females aged 25 (15.2 per 100,000). 91.6% were treated medically, 7.6% had a cerebrospinal fluid diversion procedure. Elective caesarean sections rates were significantly higher in IIH (16%) compared to the general population (9%), p<0.005. Admission rates rose by 442% between 2002 and 2014, with 38% having repeated admissions in the year following diagnosis. Costs rose from £9.2 to £50 million per annum over the study period with costs forecasts of £462 million per annum by 2030.

Conclusions IIH incidence is rising (by greater than 100% over the study), highest in areas of social deprivation and mirroring obesity trends. Re-admissions rates are high and growing yearly. The escalating population and financial burden of IIH has wide reaching implications for the health care system.