Inappropriate Prescribing of Parenteral Vitamin B₁₂

Despite studies showing that oral vitamin B₁₂ supplementation generally is as effective as parenteral administration in normalizing serum B₁₂ levels even in patients with pernicious anemia, widespread use of vitamin B₁₂ injections persists. In this retrospective study, researchers used an Ontario, Canada, claims health system administrative databases to identify 147,000 older patients (age, ≥65) who received a total of 405,000 intramuscular vitamin B₁₂ injections between 2011 and 2015.

During 1 year before a patient's first B₁₂ injection, 25% of patients had documented normal serum B₁₂ levels, and 38% had no B₁₂ level documented at all. Overall, nearly two thirds of injections were deemed inappropriate. Only 2500 patients (1.7%) had evidence…