We obtained the names, addresses and prescriber identification numbers of 2800 primary care physicians and attempted to link these with the Ontario Drug Benefit database. We successfully linked the names and prescriber numbers of 2520 physicians. To reduce the chance of contamination between the study arms or reinforcement of the intervention through participant interaction, we did not select physicians with the same address as another participant. Baseline prescribing patterns were screened to ensure that potential participants wrote at least 10 prescriptions for the target drugs in a 2-month period. Of the remaining 1624 eligible physicians, 812 were randomly assigned to the intervention group and 812 to the control group. Randomization was carried out before consent, following Zelen's method,10
because it was important that control physicians did not know that their prescribing patterns were being compared with those of the physicians in the intervention group ().11
The control group received a similar feedback and education program about prescribing first-line antihypertensive drugs.
Physicians who were randomly assigned to the intervention were invited to consent to a program of feedback about their prescribing and education about benzodiazepine prescribing for elderly people. The physicians were assured that a strict confidentiality protocol was in place whereby no one on the project staff would have access to both their name and their profile, nor would their profiles be made available to the Ontario Ministry of Health and Long-Term Care or any outside agency. It was made clear to study participants that no judgement was being made about the appropriateness of the individual prescriptions, because the claims data did not include sufficient clinical information to make such an evaluation. Initial invitations to participate were followed by 2 reminders to nonresponders at 2-week intervals. Eight packages were returned as undeliverable. Responses were received from 355 of the 804 who received packages, of whom 168 wished to participate, giving an overall consent rate of 21%.
Because physicians who consent to educational interventions may have practices that differ systematically from those who do not give their consent, we also identified a control group of individuals who agreed to participate in the study. Participants in the control arm of the study agreed to receive educational material and feedback about their antihypertensive prescribing for elderly patients. Three packages were returned as undeliverable. Responses were received from 381 of the 809 physicians who received packages, of whom 206 wished to participate, giving an overall consent rate of 25%.
The intervention consisted of mailed packages of feedback about the participants' prescribing and evidence-based educational materials, which were sent every 2 months for 6 months. The initial feedback report, mailed Jan. 1, 1999, gave baseline data for January and February 1998. Feedback pertaining to baseline data for March and April 1998 was mailed on Mar. 1, 1999, and feedback pertaining to baseline data for May and June 1998 was mailed on May 1, 1999. Feedback was presented as bar graphs comparing the prescriber with his or her peers and with a hypothetical “best practice” in 4 categories: (1) number of prescriptions per 100 seniors, (2) percentage of long-acting benzodiazepines prescribed, (3) duration of therapy (% of prescriptions for longer than 3 months) and (4) combination therapy (% of benzodiazepine and psychoactive drug combinations). The “best practice” was defined as the benzodiazepine-prescribing patterns of 100 physicians who regularly prescribed benzodiazepines but avoided the pitfalls of using long-acting drugs, combinations of drugs and long-term therapy. This was included in the graphs in order to counteract the potential social desirability effect of the peer group comparison. A sample feedback report is shown in Appendix 1
(an expanded version of Appendix 1 may be found on www.cmaj.ca
The educational bulletins that accompanied the feedback profiles were written in a brief, informal style with an emphasis on practical tips. In addition, we included information sheets that physicians could give to patients. These were relatively simply designed in order to distinguish them from commercial promotional materials. Topics and content were selected on the basis of focus group work with 3 groups of primary care physicians, regarding challenges in the safe and effective prescribing of benzodiazepines for elderly patients.
We prepared the feedback profiles from claims data for prescriptions under the Ontario Drug Benefit program. Available data fields included date of filling of the prescription, drug identification number, quantity, professional fee, charges claimed from the Ontario Drug Benefit program, and scrambled patient and physician identification numbers whereby the drug history of an individual patient or prescriber could be assembled but could not be linked to that person's identity. For the study physicians, we extracted claims for all benzodiazepines from the dataset.
We evaluated participants' satisfaction with the intervention through a mailed survey to the 168 participants in the intervention group.
The intervention was offered from Jan. 1, 1999, to June 30, 1999, and January through June 1998 was chosen to be the baseline period. The “washout” (post-intervention monitoring period) was from July 1, 1999, to Dec. 31, 1999.
We calculated the percentage of long-acting benzodiazepine prescriptions as a proportion of all benzodiazepine prescriptions for each physician. We defined the following as long-acting drugs: chlordiazepoxide, clonazepam, clorazepate, diazepam, nitrazepam and flurazepam. Alprazolam, bromazepam, lorazepam, oxazepam, triazolam and temazepam were defined as short-acting drugs. To obtain the percentage of seniors on long-term therapy, we divided the number of patients who were prescribed long-term benzodiazepine therapy by the number of all seniors receiving benzodiazepine prescriptions from each physician. Long-term therapy was defined as benzodiazepine therapy lasting 60 days or more. We used the recommended daily dose to calculate the duration of each prescription, which had to be from the same physician who was participating in our study. We calculated the percentage of benzodiazepine prescriptions considered to be combination therapy as a proportion of the total number of benzodiazepine prescriptions. Combination therapy was identified where 1 or more psychoactive drugs from a pre-defined list were prescribed concurrently with a benzodiazepine. The drugs had to be prescribed by the same physician who was participating in our study, and the dispensing date of the benzodiazepine prescription minus the dispensing date of the other prescription had to equal 7 days or less.
Ethics approval for the study was received from the Research Ethics Board at Women's College and at the University of Toronto, Toronto, Ont.