• C G van Walraven and C D Naylor.
• University of Ottawa, Ont. carlv@lri.ca
• CMAJ. 1999 Jul 27; 161 (2): 146-9.

BackgroundExcess use of parenteral vitamin B12 has been reported from audits of clinical practices. The authors assessed the use of vitamin B12 injections in patients aged 65 years and over in Ontario.MethodsA cross-sectional analysis was conducted that included all elderly people covered by the Ontario Health Insurance Plan who received insured services from general practitioners or family physicians (GP/FPs). For each practice the proportion of elderly patients who received regular vitamin B12 injections between July 1996 and June 1997 was calculated. The frequency of injections was determined for each patient receiving regular B12 replacement.ResultsOf the 1,196,748 elderly patients (mean age 74.8 [standard deviation 6.8], 58.0% female) treated by 14,177 GP/FPs, 23,651 (2.0%) received regular B12 injections. The rate of B12 injections per patient, standardized for age and sex, varied between practices (range 0%-48.6%). Although no authoritative sources support the practice, 3303 (19.8%) of the 16,707 patients receiving long-term parenteral therapy had, on average, overly frequent injections (more than 1 injection every 4 weeks). For 76 (12.3%) of the 617 practices with 10 or more patients receiving regular vitamin B12 injections, the mean injection frequency was greater than once every 4 weeks. The proportion of patients in these 617 practices who received overly frequent injections varied extensively (0%-100%).InterpretationOur findings indicate that some primary care physicians in Ontario administer unnecessary vitamin B12 injections to elderly patients.

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