Use of vitamin B-12 injections among elderly patients by primary care practitioners in Ontario

Background: Excess use of parenteral vitamin B-12 has been reported from au dits of clinical practices. The authors assessed the use of vitamin B-12 in jections in patients aged 65 years and over in Ontario. Methods: A cross-sectional analysis was conducted that included all elderly people covered by the Ontario Health Insurance Plan who received insured s ervices from general practitioners or family physicians (GP/FPs). For each practice the proportion of elderly patients who received regular vitamin B- 12 injections between July 1996 and June 1997 was calculated. The frequency of injections was determined for each patient receiving regular B-12 repla cement. Results: Of the 1 196 748 elderly patients (mean age 74.8 [standard deviati on 6.8], 58.0% female) treated by 14 177 GP/FPs, 23 651 (2.0%) received reg ular B-12 injections. The rate of B-12 injections per patient, standardized for age and sex, varied between practices (range 0%-48.6%). Although no au thoritative sources support the practice, 3303 (19.8%) of the 16 707 patien ts 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 B-12 injectio ns, the mean injection frequency was greater than once every 4 weeks. The p roportion of patients in these 617 practices who received overly frequent i njections varied extensively (0%-100%). Interpretation: Our findings indicate that some primary care physicians in Ontario administer unnecessary vitamin B-12 injections to elderly patients.