Chen Yan, Kelton Christina M L, Jing Yonghua, Guo Jeff J, Li Xing, Patel Nick C
Division of Pharmacy Practice and Administrative Sciences, University of Cincinnati College of Pharmacy, 3225 Eden Avenue, Cincinnati, OH 45267-0004, USA.
Res Social Adm Pharm. 2008 Sep;4(3):244-57. doi: 10.1016/j.sapharm.2007.06.019. Epub 2008 Aug 8.
Antidepressants are often used in the treatment of major depressive disorder and other mental illnesses, and constitute one of the most widely prescribed and costly medication classes in the US Medicaid Program. However, antidepressant utilization and price patterns within this market have not yet been adequately characterized.
This study was undertaken to analyze antidepressant drug utilization and price trends and to quantify market-share competition in Medicaid.
Quarterly utilization and payment data were retrieved from the national Medicaid pharmacy claims files provided by the Centers for Medicare & Medicaid Services. Quarterly per-prescription prices were estimated by dividing the payment amounts by the number of prescriptions. Descriptive time series analysis was conducted to assess the trends of utilization, expenditures, market shares, and prices from January 1991 through December 2005, for 3 major antidepressant subclasses--Selective Serotonin Reuptake Inhibitors (SSRIs), Tricyclic Antidepressants, and Other Antidepressants--as well as for individual agents within these subclasses. Using exponential smoothing models, 3-year market-share forecasts were produced.
From 1991 to 2005, the total number of antidepressant prescriptions rose 380% from 6.82 million to 32.72 million. Total expenditures on antidepressants increased from $159 million in 1991 to $2.26 billion in 2004, then decreased to $1.99 billion in 2005, following the entry of lower-priced generic fluoxetine in 2001 and generic paroxetine in 2003. The payment market share for the SSRIs increased from 40% in 1991 to 82% in 1997, then decreased to 64% in 2005. It is projected to be 64% (95% confidence interval [CI]: 51-77%) in 2008 quarter 4.
Increases in antidepressant drug expenditures were primarily because of rising utilization; however, there was also some increase in average price per prescription for many of the antidepressants studied. Switching to generic drugs may offer significant cost-saving potential.
抗抑郁药常用于治疗重度抑郁症及其他精神疾病，是美国医疗补助计划中处方量最大、费用最高的药物类别之一。然而，该市场内抗抑郁药的使用情况及价格模式尚未得到充分描述。
本研究旨在分析抗抑郁药的使用情况及价格趋势，并量化医疗补助计划中的市场份额竞争。
从医疗保险和医疗补助服务中心提供的全国医疗补助药房索赔档案中检索季度使用量和支付数据。通过将支付金额除以处方数量来估算季度每张处方的价格。进行描述性时间序列分析，以评估1991年1月至2005年12月期间3种主要抗抑郁药亚类——选择性5-羟色胺再摄取抑制剂（SSRI）、三环类抗抑郁药和其他抗抑郁药——以及这些亚类中各药物的使用量、支出、市场份额和价格趋势。使用指数平滑模型得出3年的市场份额预测。
1991年至2005年，抗抑郁药处方总数从682万增至3272万，增长了380%。抗抑郁药总支出从1991年的1.59亿美元增至2004年的22.6亿美元，随后在2001年低价通用型氟西汀和2003年通用型帕罗西汀进入市场后，于2005年降至19.9亿美元。SSRI的支付市场份额从1991年的40%增至1997年的82%，随后在2005年降至64%。预计在2008年第4季度为64%（95%置信区间[CI]：51 - 77%）。
抗抑郁药支出增加主要是由于使用量上升；然而，所研究的许多抗抑郁药每张处方的平均价格也有所上涨。改用通用型药物可能具有显著的成本节约潜力。
