Quarterly, state level data on prescription drug utilization are available from the Health Care Financing Administration(now known as Centers for Medicare and Medicaid Services(CMS)) (HCFA(now known as CMS)). These data are reported at the National Drug Code (NDC) level, allowing analysis of utilization of individual pharmaceutical agents within the Medicaid system. While these data are representative of the US Medicaid population, state-level analyses are difficult in some States due to missing data. The completeness of the data is also compromised in States where Medicaid Managed Care has assigned the responsibility for paying for pharmaceuticals to the participating managed care organizations.
Although there are limitations in the data, The Lewin Group conducted time-series analysis of antidepressant and antipsychotic drug utilization data between 1985 and 1998 for 45 States. Data from six States were excluded for the following reasons:
- Arizona and Tennessee do not report Medicaid drug utilization data at all;
- Texas has not reported since the second quarter of 1995;
- Colorado has not reported since the fourth quarter of 1996;
- Data from Indiana appears very erratic;
- 1995 and 1996 data from Wyoming appear to be off by a factor of 10; and
- Connecticut did not report data for 1998.