the drug load was determined for antidepressants,benzodiazepines,and antipsychotics,but not for anticonvulsant since the available DDD was for the primary indication of epilepsy. In this study,the actual dose taken by patient was use as the PDD. only patient who took any drug within a medication class for 50% of day were included in the calculation. the PDD/DDD ratio was calculated for each drug and summed for all drug taken within a medication class. if a patient took multiple regimens with the same drug count within a medication class,the PDD/DDD ratio for each regimen was weight by the percent of day taken