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CMAJ
CMAJ - May 2, 2000JAMC - le 2 mai 2000

Vitamin B12 injections for the elderly

CMAJ 2000;162:1275


In response to: F. Anello
We agree that treatment of true cobalamin (vitamin B12) deficiency is very important and should continue. We also agree that one might reasonably err on the side of overtreatment.

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 methodologies9,10 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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References

  1. Matchar DB, McCrory DC, Millington DS, Feussner JR. Performance of the serum cobalamin assay for diagnosis of cobalamin deficiency. Am J Med Sci 1994;308:276-83. [MEDLINE]
  2. van Walraven CG, Naylor CD. Use of vitamin B12 injections among elderly patients by primary care practitioners in Ontario. CMAJ 1999;161(2):146-9. [MEDLINE]
  3. Lindenbaum J, Rosenberg IH, Wilson PW, Stabler SP, Allen RH. Prevalence of cobalamin deficiency in the Framingham elderly population. Am J Clin Nutr 1994;60:2-11. [MEDLINE]
  4. Yao Y, Yao SL, Yao SS, Yao G, Lou W. Prevalence of vitamin B12 deficiency among geriatric outpatients. J Fam Pract 1992;35:524-8. [MEDLINE]
  5. Norman EJ. Vitamin B12 deficiency. J Fam Pract 1993;36(6):597. [MEDLINE]
  6. Pacala JT. Vitamin B12 deficiency. J Fam Pract 1993;36(4):373. [MEDLINE]
  7. Canadian Task Force on the Periodic Health Examination. The Canadian guide to clinical preventive health care. Ottawa: Health Canada; 1994.
  8. Naglie G, Tansey C, Krahn MD, O'Rourke K, Detsky AS, Bolley H. Direct costs of coronary artery bypass grafting in patients aged 65 years or more and those under age 65. CMAJ 1999;160(6):805-11. [MEDLINE]
  9. Jaeschke R, Guyatt G, Sackett DL. Users' guides to the medical literature. III. How to use an article about a diagnostic test. A. Are the results of the study valid? JAMA 1994;271:389-91. [MEDLINE]
  10. Jaeschke R, Guyatt GH, Sackett DL. Users' guides to the medical literature. III. How to use an article about a diagnostic test. B. What are the results and will they help me in caring for my patients? JAMA 1994;271:703-7. [MEDLINE]
  11. Lederle FA. Oral cobalamin for pernicious anemia. Medicine's best kept secret. JAMA 1991;265:94-5. [MEDLINE]
  12. Elia M. Oral and parenteral therapy for B12 deficiency. Lancet 1998;352:1721-2. [MEDLINE]
  13. Kuzminski AM, Del Giacco EJ, Allen RH, Stabler SPO, Lindenbaum J. Effective treatment of cobalamin deficiency with oral cobalamin. Blood 1998;92:1191-8. [MEDLINE]

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