Vitamin B₁₂ injections for the elderly

CMAJ 2000;162:1275

However, 2 issues regarding vitamin B₁₂ deficiency must be considered when framing the problem of variations in utilization. First, as indicated by Francesco Anello, many of the symptoms of vitamin B₁₂ deficiency are extremely nonspecific. Second, measurements of serum vitamin B₁₂ levels do not discriminate between those patients with true vitamin B₁₂ deficiency and those with low serum levels.¹ We believe that the combination of nonspecific symptoms with a nonspecific laboratory test helps explain the large variations in parenteral vitamin B₁₂ utilization between practices that we reported in our article [Evidence].²

Anello raises several interesting points on which we would like to comment. First, the prevalence of biochemical evidence of vitamin B₁₂ deficiency in the Framingham cohort was low.³ Review of Fig. 2 in the report by Lindenbaum and colleagues³ shows that 14 elderly patients with low serum levels of vitamin B₁₂ had elevated serum methylmalonic acid levels. Since the cohort involved 548 elderly people, 2.5% showed biochemical evidence of vitamin B₁₂ deficiency.

Second, the data reported by Yao and colleagues⁴ do not justify screening for vitamin B₁₂ deficiency.^5,6 Since 8% of the study participants had symptoms or signs of vitamin B₁₂ deficiency prior to testing and would therefore have been tested on a case-finding basis, it does not appear that this was a general inception cohort. More generally, evidence for screening is lacking and is not recommended by others.⁷

Finally, the cost of vitamin B₁₂ injections could be considerable at the population level. We used the database of the Ontario Drug Benefit program to identify all 34 264 elderly people who were prescribed parenteral vitamin B₁₂ in 1996. Using claims in the Ontario Health Insurance Plan database, we calculated the direct cost of all physician visits associated with vitamin B₁₂ injections in the year following the prescription date to be $4.2 million. This would pay for approximately 250 uncomplicated coronary artery bypass graft surgeries in elderly patients [Evidence].⁸

Where should we go from here? First, we need further research using appropriate methodologies^9,10 to find methods of determining true vitamin B₁₂ deficiency. Second, the role of high-dose oral vitamin B₁₂ supplementation needs elucidation.^11,12,13 Finally, since low serum levels do not necessarily equate with vitamin B₁₂ deficiency, we need natural history studies and rigorous intervention trials to determine the most effective and efficient way to manage patients with nonspecific symptoms and low serum vitamin B₁₂ levels.

Carl G. van Walraven
Clinical Epidemiology Unit
Loeb Research Institute
Ottawa, Ont.
C. David Naylor
Faculty of Medicine
University of Toronto
Toronto, Ont.

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