摘要：Objectives. We assessed whether state Medicaid preferred drug lists are concordant with the World Health Organization's 2009 16th Essential Medicines List and with each other. We also characterized listed medicines by generic availability and appearance on treatment guidelines. Methods. We derived generic availability and first-line treatment status from the US Food and Drug Administration's Orange Book and the 2004–2009 National Health Service National Institute for Clinical Excellence guidelines. We report characteristics of Essential Medicines List and preferred drug list (PDL)-only medicines and describe differences between medicines that are frequently and infrequently listed on PDLs. Results. Only 6 of 120 Essential Medicines List medicines appeared on fewer than 50% of PDLs. PDL-only medicines (n = 249) were less likely than were Essential Medicines List medicines (n = 120) to have generic versions available (56% vs 76%) and to be first-line treatments (21% vs 41%). The content of PDLs was variable: 33% of medicines appeared on 80% to 100% of PDLs. Conclusions. Application of the essential medicines concept to Medicaid PDLs could reduce costs and provide more equitable and evidence-based health care to low-income patients in the United States. The essential medicines concept is designed to promote the availability, accessibility, affordability, quality, and rational use of medicines that meet public health needs. 1 A key element of the concept is the World Health Organization (WHO) Essential Medicines List, which serves as a model for public supply and reimbursement. The first WHO Essential Medicines List was drafted in 1977 to address the gap in medication access between citizens of high- and low-income countries. The list aimed to highlight the most critical medicines for the needs of the national population. 1 Since 2002, biannual revisions of the list have adhered to rigorous standards of evidence and consider disease prevalence and the safety and efficacy of medicines. 2 Relative cost may be evaluated as well, but no medicine is excluded from consideration because of high cost. 3 Additional features of the essential medicines concept are the development of evidence-based clinical guidelines and a national medicines policy. WHO advises countries to adapt the Essential Medicines List according to their priority health care needs. 1 In 2007, WHO found that 131 of 151 countries surveyed (87%) had a national essential medicines list. However, discrepancies exist between the WHO Essential Medicines List and these national lists, for a variety of reasons. For example, an Essential Medicines List medicine may not be a recommended therapy on a national guideline, or a medicine deemed as essential by the WHO may not be licensed in a country. An essential medicines list can serve as a model for procurement, local licensing and manufacturing, and the rational use of high-quality essential medicines. It also helps in allocating limited resources effectively and can be used as an advocacy tool to ensure that essential medicines are available and affordable for the population. The United States does not officially consult the Essential Medicines List, nor does it have a national medicines list. 1 In the United States, the Medicaid program was enacted in 1965 to provide health care services to eligible low-income individuals, including families with children, the elderly, and the disabled. 4 Currently, about 20% of the US population—60 million people—are enrolled in Medicaid, 4 a number expected to increase with recent health care reforms. Medicaid preferred drug lists (PDLs) enumerate medicines that are fully reimbursed by Medicaid without prior authorization. 5 Each state's Medicaid agency maintains a single PDL for its fee-for-service patients. No standardized method for PDL development across states currently exists. 6 As of May 2010, 11 states make financial contributions to the Drug Effectiveness Review Project, 7 which offers evidence-based drug class reviews. However, many states offer no information on their PDL development process. One review of 18 studies of restrictive Medicaid formularies noted that none of the studies provided details as to how the formularies were constructed. 8 One small study suggests that PDLs vary widely, but neither a large-scale comparison of PDLs nor a characterization of the most variable or most consistent medicines currently exists. 6 Low-income countries use the WHO Essential Medicines List to target their scarce resources for the procurement of the most-needed medicines. 3 Medicaid drug reimbursements are linked to PDLs that are developed by each state. Thus, Medicaid recipients, who are typically low-income people, are likely to receive medicines from these preferred drug lists. 6 Our objectives were (1) to determine whether Medicaid patients have access to all Essential Medicines List medicines, (2) to assess the concordance between the Essential Medicines List and PDLs, and (3) to evaluate the consistency of PDLs. To better understand sources of variability among PDLs and the Essential Medicines List, we describe whether listed medicines had generic versions available and whether they are recommended as first-line treatments in evidence-based clinical guidelines. We expected that PDLs would have more brand name–only medicines and fewer first-line treatments than would the Essential Medicines List.
