Rapidly Rising Incidence of Cerebrospinal Fluid Shunting Procedures for Idiopathic Intracranial Hypertension in the United States, 1988–2002

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Obesity, a major risk factor for idiopathic intracranial hypertension (IIH), is rapidly increasing in all ages of the United States population. We studied trends in the incidence of cerebrospinal fluid (CSF) shunts for IIH in the United States between 1988 and 2002, using a national hospital discharge database. This was a retrospective study using the Nationwide Inpatient Sample and robust weighted least-squares regression, adjusted for stratified survey methodology. There were 2779 admissions for CSF shunting procedures (new or revision) in IIH patients in the database. In-hospital mortality for new shunts was 0.5% (0.9% for ventricular shunts and 0.2% for lumbar shunts). The estimated total United States caseload of CSF shunting procedures for IIH increased 350% between 1988 and 2002 (P < 0.001). (The 2002 United States caseload was 1370 admissions). New shunt placements increased 320% during this interval (P < 0.001). In some subpopulations in which obesity is less important as a risk factor for IIH, caseload increases were less marked: pediatric IIH shunting (age < 13 yr) increased 52% and shunting in male IIH patients increased 38%, but shunting in older patients (age > 44 yr) increased 240% during the study period. Bariatric procedures (e.g., gastric bypass) increased very rapidly in incidence since 1998, with nearly 200 such procedures performed on IIH patients in 2002. The incidence of CSF shunting for IIH is increasing in the population of the United States at about the same relative rate as morbid obesity. Studies to establish the best shunting method in IIH and to explore alternative treatment strategies, such as optic nerve sheath fenestration and bariatric surgery, are urgently needed.