Law Michael R, Ross-Degnan Dennis, Soumerai Stephen B
Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, MA 02215, USA.
Psychiatr Serv. 2008 May;59(5):540-6. doi: 10.1176/ps.2008.59.5.540.
Medicaid expenditures for antipsychotic medications have risen rapidly, from under $1.0 billion in 1995 to over $5.5 billion in 2005. In response, at least ten states have implemented prior-authorization programs that restrict access to particular second-generation antipsychotic agents (aripiprazole and olanzapine). Twenty-two states restrict particular dosing forms (injections). This study examined the impact of such restrictions.
The authors used interrupted time-series analysis of quarterly state-level drug utilization data to examine the impact of prior authorization for particular agents in West Virginia and Texas. Changes in market share of nonpreferred medications and total pharmacy costs were compared with changes in states without similar prior-authorization requirements.
The West Virginia policy led to an immediate 3.5% reduction in market share level (p<.01) and a 1.3% decrease in trend per quarter in market share (p<.001) for nonpreferred antipsychotics, leading to a 13.9% reduction after two years. In Texas, prior authorization reduced the market share level of nonpreferred agents by 2.6% (p=.055). However, prior authorization did not lead to a significant decrease in pharmacy reimbursements in either state.
Current prior-authorization policies for second-generation antipsychotics do not appear to reduce pharmacy reimbursement, probably because alternative medications are costly. These findings suggest that any cost savings from prior-authorization policies would accrue largely through supplemental rebate agreements with manufacturers, which are likely reduced by the transfer of dually eligible Medicaid enrollees to Medicare Part D plans. Further evaluation of the clinical consequences resulting from such policies is urgently needed to determine whether the minimal cost savings outweigh the potential clinical risks.
医疗补助计划用于抗精神病药物的支出迅速增长，从1995年的不到10亿美元增至2005年的超过55亿美元。作为应对措施，至少有10个州实施了预先授权计划，限制使用特定的第二代抗精神病药物（阿立哌唑和奥氮平）。22个州限制特定剂型（注射剂）。本研究考察了此类限制措施的影响。
作者采用季度州级药物使用数据的中断时间序列分析，考察西弗吉尼亚州和得克萨斯州对特定药物实行预先授权的影响。将非首选药物的市场份额变化和药房总费用变化与没有类似预先授权要求的州的变化进行比较。
西弗吉尼亚州的政策导致非首选抗精神病药物的市场份额水平立即下降3.5%（p<0.01），且每季度市场份额的下降趋势为1.3%（p<0.001），两年后下降了13.9%。在得克萨斯州，预先授权使非首选药物的市场份额水平下降了2.6%（p=0.055）。然而，预先授权在这两个州均未导致药房报销费用显著下降。
目前针对第二代抗精神病药物的预先授权政策似乎并未降低药房报销费用，可能是因为替代药物成本高昂。这些研究结果表明，预先授权政策带来的任何成本节约很大程度上都将通过与制造商的补充回扣协议实现，而双重资格的医疗补助计划参保人向医疗保险D部分计划的转移可能会减少此类协议。迫切需要进一步评估此类政策导致的临床后果，以确定最低限度的成本节约是否超过潜在的临床风险。
