Forty two of the 48 peer review groups in the region of Utrecht were eligible and invited to participate. Twelve peer review groups (100 general practitioners) agreed to participate (). Insurance claims data showed no differences in volumes of antibiotics prescribed in participating compared with non-participating doctors. Out of 100 general practitioners who agreed to participate, 89 completed the study. Eleven were lost to follow up (intervention group 4/46; control group 7/54) because of retirement (one doctor), removal outside the region (three), illness (three), motivational problems (two) or technical problems (two). General practitioners in both arms did not differ at baseline with regard to sex, practice characteristics, and mean period since registration as general practitioner (). They did not differ either regarding the extent to which the group was used to discuss indication and first choice medication in their meetings (). Registered patients in both arms did not differ in 2000 and 2001 regarding age, sex, and type of diagnosis (). Almost 80% (37) of the general practitioners (intervention group) attended all parts of the intervention.
Flow of participants through the trial.
Baseline characteristics of general practitioners (n=89) participating in the study in 2000
Patients' characteristics in 2000 and 2001 in the intervention and control groups
At baseline, mean antibiotic prescription rates for registered encounters for respiratory tract symptoms did not differ significantly between the two groups (27% v 29%, 95% confidence interval -9.1 to 5.0). In 2001, antibiotic prescription rates in the intervention group fell by 4% and those in the control group rose by 8% (mean difference in change -12%, -18.9% to -4.0%, ). Multilevel analysis confirmed the results of the unadjusted analysis (intervention effect -10.7%, -20.3% to -1.0%), while intra-class correlation coefficients showed that variation could be attributed to practice and group levels 0.17 and 0.09, respectively).
Registration of patients: changes in antibiotic prescription rates and patients' satisfaction in 2000 and 2001. Values are means with standard deviations unless otherwise indicated
Patient satisfaction questionnaires were available from 83% (35) of general practitioners in the intervention group and from 91% (43) of doctors in the control group (). We found no difference in patients' satisfaction in the two arms in 2000 and 2001 (). The multiple intervention did not change patients' degree of satisfaction; they remained very satisfied with the consultation (mean satisfaction grade 4.2). These results were also confirmed by multilevel analysis (intervention effect on patients' satisfaction -0.03, -0.2 to 0.1).
Claims data over 2000 and 2001 were in line with our results: no significant differences occurred in the number of antibiotic prescriptions between intervention and control group in 2000. In 2001, however, the mean number of antibiotic prescriptions had decreased by 9.7 prescriptions per 1000 patients (P = 0.05) in the intervention group, whereas in the control group it had increased (P = 0.60). This increase was also seen in the non-participating general practitioners in the same region (mean difference in change between intervention and control group -11.6 prescriptions/1000 patients, -23.2 to -0.03) and confirmed by multilevel analysis (). After 15 months, the number of antibiotic prescriptions in the intervention group was still lower than in the pre-intervention period (data not shown). Referral rates (about 2%) remained stable over time and did not differ between intervention and control groups (mean difference in change -0.1, -2.0 to 1.8).
Insurance claims data: changes in mean number of antibiotic prescriptions per 1000 patients in March-April-May 2000 and March-April-May 2001 at practice level. Values are means with standard deviations