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Idiopathic Normal Pressure Hydrocephalus in the United States: Demographic and Socioeconomic Disparities

Research paper by Rafi A, Mehdizadeh R, Ghaffari-Rafi S, et al.

Indexed on: 14 Mar '21Published on: 16 Nov '20Published in: Neurosurgery



Abstract

INTRODUCTIONWith early intervention, up to 80% of idiopathic normal pressure hydrocephalus's (iNPH) patients may clinically improve, thus there is impetus to understand pathophysiology and sooner identify patients for treatment. By characterizing risk factors and how disease is distributed amongst a population, epidemiology provides an avenue for identifying iNPH’s pathogenesis.METHODSTo investigate iNPH incidence with respect to sex, age, income, residence, and race/ethnicity, we queried the largest American administrative dataset, the National (Nationwide) Inpatient Sample (NIS), which surveys 20% of United States (US) discharges. Subsequently, median annual incidence (per 100,000 people) and disease trends between 2008–2016 were determined.RESULTSAnnual national iNPH incidence (with 25th and 75th quartiles) was 2.86 (2.72, 2.93). Males had an incidence of 3.27 (3.11, 3.39), larger (P = .008) than the female incidence of 2.45 (2.41, 2.47). Amongst age groups incidence varied (tau = 30.4, P = .000004) as follows: 1–17 years old group, 0.00 (0.00, 0.00); 18–44 group, 0.064 (0.058, 0.076); 45–64 group, 11.91 (10.99, 12.73); 65–84 group, 17.89 (17.22, 18.69); 85+ group, 18.81 (16.40, 19.95). Individuals with middle/high income had an incidence of 2.96 (2.77, 3.06), larger (P = .008) than the 2.37 (2.24, 2.53) of low income patients. Depending on whether patients lived in urban, suburban, or rural communities, incidence diverged (tau = 9, P = .01) as follows, respectively: 2.65 (2.43, 2.84); 2.66 (2.56, 2.83); 3.036 (2.96, 3.19). Living in a rural community resulted in a significantly greater incidence, relative to urban (P = .03) or suburban (P = .04). Amongst race/ethnicity (tau = 30.8, P = .000003), incidence for Whites, Blacks, Hispanics, Asian/Pacific Islanders, and Native Americans were as follows, respectively: 3.88 (3.69, 3.93), 1.065 (1.015, 1.14); 0.82 (0.76, 0.85); 0.43 (0.33, 0.52); 0.027 (0.026, 0.12).CONCLUSIONIn the US, iNPH annual incidence (2008-2016) was found to be 2.86 per 100,000 people, with existing disparities between socioeconomic and demographic strata. Disproportionately, incidence was greatest for patients who were White, male, 65 and older, middle/high income, and living in rural communities. In summary, the data emphasizes a healthcare inequality amongst iNPH and provides insight for etiology elucidation.