Off-label use of antidepressant, anticonvulsant, and antipsychotic medications among Georgia medicaid enrollees in 2001.

Objectives: To determine the prevalence of and factors associated with the off-label use of antidepressant, anticonvulsant, and antipsychotic medications.

Method: A retrospective analysis of Georgia Medicaid recipients was conducted. Recipients prescribed antidepressant, anticonvulsant, or antipsychotic medications were identified. Logistic regression analysis was used to identify factors associated with off-label use.

Results: A total of 46,976 (75.42%) antidepressant recipients, 38,497 (80.12%) anticonvulsant recipients, and 21,252 (63.62%) antipsychotic recipients received at least 1 of these medications off-label in 2001. The likelihood of receiving off-label medications increased remarkably with advancing age (>or= 65 vs. < 65 years: antidepressant: OR = 5.15, 95% CI = 4.76 to 5.56; anticonvulsant: OR = 4.54, 95% CI = 4.16 to 4.96; antipsychotic: OR = 5.21, 95% CI = 4.82 to 5.63). Although receiving new anticonvulsants launched after 1993 was the strongest predictor (OR = 7.63, 95% CI = 7.07 to 8.23) of receiving off-label anticonvulsant medications, exposure to newer antidepressants and antipsychotics did not confer a higher chance of receiving off-label medications (selective serotonin reuptake inhibitors vs. tricyclic antidepressants: OR = 0.43, 95% CI = 0.40 to 0.45; atypical vs. conventional antipsychotics: OR = 0.76, 95% CI = 0.72 to 0.80).

Conclusions: The off-label use of antidepressant, anticonvulsant, and antipsychotic medications is highly prevalent. Further research to study the effects of off-label use among this high risk subpopulation may be an important step toward defining the scope of and potential for such use.