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 > or =65 years old from a national database of 20 million age-qualified patients. Cases received > or =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 > or =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.