OBJECTIVES: None of the published literature comparing outcomes measures between serotonin reuptake inhibitors (SSRIs) and sertonin-norepinephrine reuptake inhibitors (SNRIs) control for doctors’ practice and prescribing patterns due to the limitations of claims databases. We showed how to derive doctors’ practice and prescribing patterns for this group of patients from U.S. claims data. METHODS: Based on U.S. claims data, we assigned doctors IDs based on the physician who treated the enrollee for the longest period of time after eliminating any emergency room, laboratory, and radiology services. Physician prescribing patterns were then calculated from prescription drug records. Patients were grouped as generic SSRIs, non-generic SSRIs, and SNRIs. RESULTS: We identified the doctors’ prescribing pattern with the percentage of time they prescribed SSRIs, non-generic SSRIs and SNRIs. We showed that patients were more likely to be prescribed generic SSRIs relative to non-generic SSRIs if doctors’ prescribing patterns favored generic prescription (p=0.000). Similarly, patients were less likely to be in the SSRIs group if doctors’ prescribing patterns favored SNRI prescription (p=0.000). CONCLUSIONS: Doctors’ prescribing patterns are important factors for decisions on treatment. Any outcomes models (compliance, or treatment effect on health care utilization and cost) should control for these patterns.