In Reply Drs Dharmarajan and Norkus raise the question of how to define vitamin B12 deficiency. We share this concern; thus, we performed sensitivity analyses including both a broader definition (which included International Classification of Diseases coding) and a narrower definition (which included only patients who had both a low vitamin B12 level and who were prescribed vitamin B12 supplementation). An association between long-term use of acid-suppressing medications and vitamin B12 deficiency was found with different definitions; thus, there was no evidence that the main finding was explained only by the case definition. However, we did not have dietary data for the patients.
Corley D, Lam J, Schneider J. Gastric Acid–Inhibiting Medications and Vitamin B12 Deficiency—Reply. JAMA. 2014;311(14):1445-1446. doi:10.1001/jama.2014.2101