IV immunoglobulin is associated with a reduced risk of Alzheimer disease and related disorders

Objective: To compare the incidence of Alzheimer disease and related disorders (ADRD) in patients treated with IV immunoglobulin (IVIg) for non-Alzheimer disease (AD) indications vs untreated controls. Methods: This retrospective case-control analysis used medical claims for patients >= 65 years old from a national database of 20 million age-qualified patients. Cases received >= 1 IVIg administration during April 1, 2001-August 31, 2004, had claims 1 year prior to first (index) IVIg administration to confirm absence of pre-index ADRD, and had >= 3 years of continuous claims post-index. Untreated controls had their first medical claim during April 1, 2000 -August 31, 2004, and otherwise met the same requirements as cases. Controls were matched 100: 1 to cases on age, gender, and risk factors for ADRD. The relative incidence of ADRD post-index for the IVIg-treated cases vs untreated controls was estimated using Kaplan-Meier survival curves and a Cox proportional hazards model. Results: Treated patients in the Kaplan-Meier analysis had lower ADRD incidence (p = 0.02) with an estimated 2.6% of the 847 IVIg-treated vs 4.6% of 84,700 controls diagnosed with ADRD at 60 months after index date. Treated patients in the Cox proportional hazard model had a 42% lower risk of being diagnosed with ADRD (hazard ratio, 0.577; 95% confidence interval, 0.359 to 0.930; p = 0.024) with an estimated 2.8% of treated vs 4.8% of controls diagnosed with ADRD at 60 months after index date. Conclusions: Previous treatment with IV immunoglobulin was associated with a reduced risk of developing Alzheimer disease and related disorders (ADRD) in this study. Evidence from additional studies is needed to evaluate the relationship between IVIg exposure and ADRD diagnosis. Neurology (R) 2009; 73: 180-185