Computerized pharmacy records from a large staff-model health maintena
nce organization were used to examine patterns of antidepressant use b
y primary care physicians and psychiatrists. Based on timing of prescr
iption refills, patients treated by psychiatrists were more likely tha
n those treated in primary care to continue medication for more than 3
0 days (35% vs 25%, p < 0.00001) and more likely to reach a prescribed
daily dose of 100 mg of imipramine or the equivalent (48% vs 40%, p <
0.00001). Patients treated with newer antidepressants were significan
tly more likely to continue treatment past 30 days (range from 75% for
fluoxetine to 54% for doxepin, p < 0.00001) and to reach an adequate
daily dose (range from 51% for fluoxetine to 26% for doxepin, p < 0.00
001). Psychiatrists more often prescribed newer antidepressants, and m
uch of the difference between specialties could be explained by drug s
election. These findings suggest more intensive antidepressant treatme
nt than in earlier reports, especially in primary care. More intensive
treatment with newer antidepressants may reflect more tolerable side
effects, but these observational data are liable to selection bias. An
y potential advantages of newer antidepressant medications must be bal
anced against significantly higher costs.