Health Affairs, 23, no. 1 (2004): 135-146 doi: 10.1377/hlthaff.23.1.135 © 2004 by Project HOPE	New Online   Obama's Success & Next Steps   3 Health Policy Options for President Obama   A Hybrid Proposal   Bipartisan Compromise

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Benefit Design

Benefits And Risks Of Increasing Restrictions On Access To Costly Drugs In Medicaid

Abstract

 
States are reacting to increased Medicaid drug costs by implementing cost-control policies, such as preferred drug lists (PDLs) and prior authorization. PDLs have risks as well as benefits. Targeting essential drug classes with heterogeneous patient responses and side effects could reduce appropriate care, adversely affect health status, and cause shifts to more costly types of care. Assessing inappropriate use of high-cost drugs before implementing regulations and instituting simple mechanisms to exempt high-risk patients could maximize savings and minimize harm. The current exponential growth in such policies and the limited evidence base justifies investment in research to identify which policies can achieve savings without unintended consequences.

View larger version (32K): [in this window] [in a new window]   EXHIBIT 1 Trends In Medicaid Spending For Prescription Drugs, And Drug Spending As A Proportion Of Total Medicaid Spending, 1988–2000

Although the goal of these policies is to reduce costs without reducing appropriate care, there are concerns that when used inappropriately they could result in unintended outcomes, including lower use of essential therapies; declines in health; substitution of less effective, more toxic, or more expensive medications for nonreimbursed agents; or increased use of more costly physician or institutional care.⁷ For example, well-controlled studies demonstrate that arbitrary limits on the number of Medicaid prescriptions reimbursed for chronically ill elderly and disabled people resulted in a 35 percent reduction in the use of clinically essential drugs (such as insulin), particularly among people with mental health problems or chronic pain; increased exacerbation of chronic illness; and a 200 percent increase in the use of services (such as nursing homes and emergency mental health services) whose costs exceeded the cost of drugs.⁸ In one study, increases in the use of emergency services among schizophrenic patients after a cap on the number of prescriptions outweighed drug savings by a factor of seventeen to one.⁹ Even moderate drug cost sharing was found, in a recent well-controlled study, to reduce use of essential medications among low-income and elderly populations, increase hospitalization and nursing home admissions, and increase mortality.¹⁰

This paper examines the implications of the more recent, widespread adoption of policies encouraging use of less costly drugs within a therapeutic class (for example, cholesterol-lowering medications); critically examines the evidence on the economic and clinical risks and benefits of such policies; suggests ways to reduce clinical risks and maximize savings; and ends with recommendations for research and policy.

Methods For Systematic Review Of The Evidence

Top Editor's Notes Methods For Systematic Review... Preferred Drugs And Prior... Drug Category Exclusions Increasing Patient Cost Sharing... Discussion And Conclusions Notes

 
A Harvard study team conducted computerized searches of MEDLINE (an online database of published peer-reviewed articles) as well as manual searches of medical, pharmacy, and social science literature from 1965 to March 2003, to identify all published reports evaluating the effects of prevalent administrative restrictions on the prescribing of specific drugs in state Medicaid programs or other government programs providing drug benefits to low-income and elderly beneficiaries. To be included, studies were required to evaluate the impact of prior authorization and "fail first" requirements, drug category exclusions, or increased patient cost sharing for expensive drugs on one or more of the following outcomes: medication use or expenditures; frequency, cost, or efficacy of drug substitutions for restricted drugs; underuse of effective medications; substitution of other health services for drugs; and clinical outcomes. Studies with minimally adequate research designs, such as interrupted time series with or without comparison series, and before-and-after comparison-group designs, were reviewed.¹¹ It has been shown elsewhere that uncontrolled pre-post and post-only designs produce invalid results; thus, these studies were excluded from our analysis.¹² We did include ten years of additional research not analyzed in a previous report of cost containment policies in Medicaid and also include recent well-controlled studies of innovative policies in Canadian provincial drug benefit programs that cover elderly and low-income populations and that have been considered for adoption by Medicaid programs.¹³

The evidence base on the risks and benefits of such policies, while improved somewhat over the past decade, remains weak.¹⁴ Only eight of the thirteen identified studies used an adequate research design that can control for threats to internal validity, such as preexisting changes in pharmaceutical marketing, insurance coverage, and other pharmaceutical policies. Adequately controlled studies are described below; the administrative cost-control mechanisms that they address include (1) prior authorization, (2) drug category exclusions, and (3) increased patient cost sharing for expensive drugs.

Preferred Drugs And Prior Authorization

Top Editor's Notes Methods For Systematic Review... Preferred Drugs And Prior... Drug Category Exclusions Increasing Patient Cost Sharing... Discussion And Conclusions Notes

 
The Omnibus Budget Reconciliation Act (OBRA) of 1990 disallowed the use of closed formularies (limited lists of reimbursed drugs) in Medicaid; such policies have been evaluated in a previous review.¹⁵ Recently, however, the use of PA, which is allowed under OBRA 1990, to limit use of particular medications has grown rapidly.¹⁶ Many states have established PDLs that generally promote use of lower-cost drugs within classes of medications considered to have equivalent efficacy but might also discourage use of less effective drugs. Under PA, preapproval is required for reimbursement of drugs that are not on PDLs. According to OBRA 1990, states must respond to clinicians’ requests for PA within twenty-four hours and provide a seventy-two-hour emergency drug supply while the request is being processed. Although some state Medicaid programs use evidence-based criteria to establish their PDLs, others are placing large numbers of medications on PA lists largely on the basis of price or provision of supplemental rebates.¹⁷ For example, Michigan requires PA for nonpreferred drugs in forty medication categories. The number of states with PDLs has grown from three in 2000 to twenty-two in 2003.¹⁸ About forty states have some form of PA program.¹⁹

"Fail first" policies are PA mechanisms that require patients to have failed a lower-cost treatment (for example, a generic nonsteroidal anti-inflammatory drug [NSAID], such as ibuprofen, for treatment of arthritis) before use of a more expensive agent, such as a COX-2 inhibitor, is approved.

In theory, PA and other policies promoting substitution of preferred agents can be used to encourage more judicious use of costly, new, or potentially toxic drugs. However, some PA programs might induce physicians to avoid the hassle of seeking preauthorization of appropriate medications. Further, low-income patients who do not discover that their prescription requires prior authorization until they arrive at the pharmacy might give up attempting to fill the prescription instead of seeking the authorization. In addition, for certain therapies (such as selective serotonin reuptake inhibitor, or SSRI, antidepressants), differences in chemical composition or pharmacologic properties of individual drugs in a class could result in poorer treatment response among recipients of preferred drugs.²⁰ Many pharmacy and therapeutics (P&T) committees base formulary inclusion decisions on group comparisons of drugs in randomized clinical trials. However, such results are often inadequate for individual treatment decisions because people who do not respond to one drug are likely to respond to another in the same class.²¹ (Indeed, some states prohibit some of these types of drugs from their PA programs.)²²

Studies of prior authorization in Medicaid. Three studies provide useful evidence on the effects of PA in Medicaid. Bernard Bloom and Jake Jacobs (1985) used a pre-post design to study the effects of PA of cimetidine in the West Virginia Medicaid program.²³ Cimetidine is a highly cost-effective drug because it can prevent inpatient surgery for peptic ulcer disease.²⁴ The data indicated a striking 84 percent decline in use of cimetidine after the PA policy among Medicaid patients with peptic ulcer diagnosis at a time when its use was increasing nationwide.²⁵ Hospitalizations for peptic ulcer disease rose somewhat after policy implementation. While it is possible that other cost containment regulations affected the use of hospital services, it is reasonable to assume that the policy reduced quality of care for peptic ulcer disease, given the magnitude of the reduction in use of the medication, its established cost-effectiveness, and the few alternative therapies that existed at the time.²⁶

Walter Smalley and colleagues (1995) used a strong time-series design to evaluate the effects of a PA policy targeting nongeneric NSAIDs in the Tennessee Medicaid program.²⁷ A large number of low-cost generic NSAIDs existed at the time of the policy that could provide effective alternatives to the brand-name agents. The policy resulted in an immediate 53 percent decline in spending for NSAIDs, primarily through increased use of generic drugs, and saved an estimated $12.8 million over two years without any simultaneous effect on use of other drugs, physician visits, or hospital admissions. While this study provides some encouragement regarding the cost-effectiveness of this policy, some caution is warranted. There was a 26 percent reduction in overall use of NSAIDs, which raises concerns regarding unintended reductions in treatment of pain.²⁸ The study did not include any measures of changes in levels of pain or inflammation, both affected by NSAID treatment.

Jeffrey Kotzan and colleagues (1993) used a time-series design to examine changes in the use of H2 blockers and NSAIDs after a prior authorization policy was initiated in the Georgia Medicaid program.²⁹ Their findings indicate that the decrease in drug costs ($1.4 million per year for H2 blockers; $3 million in NSAIDs costs) was not offset by increases in the use of other health care services.

Drug Category Exclusions

Top Editor's Notes Methods For Systematic Review... Preferred Drugs And Prior... Drug Category Exclusions Increasing Patient Cost Sharing... Discussion And Conclusions Notes

 
Current federal regulations also allow Medicaid programs to eliminate reimbursement for entire categories of drugs. Examples of categories commonly excluded are medications used in the treatment of anorexia, weight gain, fertility, hair growth, and symptomatic treatment of coughs or colds; smoking-cessation products; barbiturate sedatives; benzodiazepines; and drugs approved for sale before the 1962 amendments to the Food, Drug, and Cosmetic (FD&C) Act requiring proof of drug efficacy (Drug Efficacy Study Implementation [DESI] drugs).

Studies of Medicaid drug category exclusions. I and my colleagues (1990) used forty-two months of claims (time series) data to measure the effects of withdrawing reimbursement for twelve categories of older, questionably effective, or irrational DESI drugs in almost 400,000 New Jersey Medicaid patients in 1981.³⁰ The policy reduced neither overall drug use nor spending because reduced use of DESI drugs (–22 prescriptions per 1,000 enrollees per month) was offset by equal or greater increases in use of generally newer and more costly substitute drugs (34 prescriptions per 1,000 enrollees per month). The appropriateness of substitute drugs varied greatly. For example, patients receiving irrational combination products containing asthma drugs and potent sedatives (barbiturates) prior to the policy were more likely to receive more therapeutically appropriate prescriptions for bronchodilators without sedatives after the reimbursement cutoff. However, patients who received ineffective peripheral and cerebral "vasodilators" for senile dementia and claudication were often switched to equally ineffective drugs, such as ergot alkyloids. The results suggest that simply stopping payment for even irrational therapies does not address the perceived need for drugs by patients and physicians and can result in both appropriate and inappropriate substitution effects.

Increasing Patient Cost Sharing For Expensive Drugs

Top Editor's Notes Methods For Systematic Review... Preferred Drugs And Prior... Drug Category Exclusions Increasing Patient Cost Sharing... Discussion And Conclusions Notes

 
An increasingly popular approach to contain drug costs is to impose economic disincentives against patients’ use of specific high-cost drugs. Sometimes called differential cost sharing, these policies differ from PA in their reliance on economic rather than procedural barriers to use of nonpreferred medications. These policies are less common in the Medicaid context than in the private sector, since federal regulations limit Medicaid drug cost sharing to nominal amounts. However, some Medicaid programs already charge higher copayments for brand-name drugs when generic equivalents exist. Programs targeted toward lower-income populations in other industrialized countries can also shed light on how cost sharing affects such populations. In particular, reference pricing (RP) of drugs, as implemented in public drug benefit programs in British Columbia, completely covers the cost of several lower-price drugs in a therapeutic class (below a "reference price") but charges patients for the extra cost of higher-price products.³¹

The efficacy of such strategies relies on the ability of expert advisory panels to identify drug classes that are "therapeutically equivalent." However, as in the case of PA, several key issues could affect the degree to which such incentives to patients affect the quality of care. These include the degree to which there is heterogeneity in clinical responses or risks of side effects that could make a more expensive agent the only effective drug for a given patient, and nonselective effects of cost sharing on appropriate and inappropriate care.³²

Studies of increased charges for expensive drugs. Four well-controlled studies examined the effects of several incentive-based RP policies. Sabastian Schneeweiss and colleagues (2002) reported the results of RP of agiontensin-converting enzyme (ACE) inhibitors (to treat hypertension) among more than 120,000 elderly patients in British Columbia’s Pharmacare program.³³ Use of higher-price agents declined 29 percent immediately after the policy, and use of low-cost reference drugs increased by similar amounts. The policy saved $6.7 million per year in drug expenditures.³⁴ Because of generous exemptions, only 18 percent of patients receiving high-price ACE inhibitors switched to lower-cost agents. There were no increases in use of emergency rooms or hospitalization among patients switching from high- to low-price drugs. However, there was a temporary (six-month) increase in physician visits following switching (increased expenditure of $700,000), presumably to monitor therapy while a patient switched drugs.

The overall results suggest that the policy did not increase use of acute care services. However, some important potential effects were not addressed. For example, because no blood pressure data were collected, it is not possible to determine whether or not patients had higher blood pressure, which would be associated with long-term health risks that the study did not capture. Second, RP was associated with an 11 percent reduction in use of all ACE inhibitors; it is not possible to determine how much of this reduction was attributable to inappropriate or duplicate use of antihypertensives and how much represents policy-related underuse.

Three other studies evaluated the effects of British Columbia’s policy on other drug classes. Paul Grootendorst and colleagues (2001) found that RP of nitrates, used for angina, resulted in a $15 million savings for nitroglycerin, a larger savings than for ACE inhibitors because of the large differences in price between the low-price and higher-price nitroglycerin products.³⁵ However, 8 percent of this amount represented additional spending by elderly patients who continued to use partly reimbursed medications. No data were reported on the policy’s effects on patient health or overall health care costs.

In a time-series study of random samples of BC Pharmacare beneficiaries, Thomas Hazlet and David Blough (2002) concluded that RP of H2 blockers was not associated with any increased use of health services and reported that the policy did not have any severe, negative effects on patients’ health.³⁶ John Marshall and colleagues (2002) also studied RP of H2 blockers in British Columbia elderly and observed a fourfold increase in use of low-price cimetidine; use of high-price agents declined more than 50 percent.³⁷ Cost savings were estimated at about $2–$3 million. However, cost shifting to patients was substantial, representing 16 percent of drug spending.

Discussion And Conclusions

Top Editor's Notes Methods For Systematic Review... Preferred Drugs And Prior... Drug Category Exclusions Increasing Patient Cost Sharing... Discussion And Conclusions Notes

 
Given the rapid increase in the use of PA policies and other cost-control mechanisms in Medicaid, the relative lack of data on their risks and benefits is cause for concern. It is sobering to realize that if such policies were considered for a clinical study, the possible risks of reduced access to essential medications would likely result in a failure to obtain human-subject approval from most institutional review boards (IRBs). These policies can be viewed as massive experiments on vulnerable populations. Nevertheless, the adequate studies reviewed above provide some evidence of both intended and unintended effects on costs and quality of care, which vary according to the types of illnesses, drug categories, and methods of implementation.

Prior authorization. PA of an effective, high-cost drug, when few alternative choices were available, almost eliminated use of the restricted agent and probably reduced appropriate care.³⁸ The effects of such policies on overall health care costs are still unknown. PA of nongeneric NSAIDs and higher-cost H2 blockers, when equally effective, inexpensive alternatives exist, greatly reduced drug spending without increasing costs and use of physician or hospital services.³⁹ However, the effects on patients’ symptoms and quality of life are still unknown.

Drug category exclusions. One large study found that withdrawal of scientifically unsubstantiated therapies and irrational combination products resulted in widespread substitution of both improved and unimproved therapies and did not reduce overall use of medications or spending.⁴⁰

Increased patient charges. Four well-controlled studies found that RP policies that charge patients for the extra cost of higher-price drugs in a class but allow generous exemptions for high-risk patients (for example, those with cardiovascular disease and diabetes) greatly reduced government spending for ACE inhibitors, nitrates, and H2 blockers.⁴¹ No increases in use of acute health care services followed RP of ACE inhibitors and H2 blockers.⁴² No data exist, however, on changes in patient-reported symptoms, quality of life, or long-term health outcomes.

Implications for research. Medicaid programs, reeling from worsening budgetary crises, are increasingly engaged in policies designed to alter the drugs prescribed to vulnerable populations of chronically ill elderly and disabled people. Research on the policy impacts of such experiments has not kept pace with policy implementation. While some policies can reduce drug spending, their effects on health status and costs remain largely unknown. The research described below is a necessary first step in increasing our understanding of the impacts of increasing restrictions on access to expensive agents, especially given the likelihood of Medicare drug coverage and accompanying cost controls in the future and the likely increased sensitivity to national policy effects on patient outcomes. It also could represent a high-priority research agenda for the National Institutes of Health (NIH), the Agency for Healthcare Research and Quality (AHRQ), and state governments.

(1) What are the economic and clinical consequences of PA and differential cost-sharing policies that promote use of lower-cost preferred drugs for major medical illnesses (such as cardiovascular disease, chronic mental illnesses, and neurologic disorders), especially in low-income Medicaid populations? Data are especially needed on the effects of such policies on use of physician, other outpatient, and hospital services. Studies should include drug classes with high patient heterogeneity in response to treatment. (2) Which policies can selectively reduce inappropriate use of costly medications while preserving appropriate drug use? (3) What are the effects on costs and quality of care of exclusions of entire categories of effective medications, such as benzodiazepines and smoking-cessation products? (4) What are the effects of such policies on direct measures of patient symptoms and health status?

Some tentative principles for policy making. Given the pressing need to cut Medicaid spending, drug cost containment policy making often cannot wait for good evidence. Thus, the following represent some tentative evidence-based principles (or prerequisite conditions) to guide policymakers in the development of policies that can maximize benefits and minimize risks to patients.

(1) Solid pharmacoepidemiological evidence or expert consensus should exist that a very high fraction of patients receiving high-cost medications in a class could be successfully treated with drugs in the same class that cost much less (such as NSAIDs, H2 blockers, or ACE inhibitors).⁴³

(2) Drug classes considered for PA should have low heterogeneity in patient response (such as H2 blockers). For example, the recent decision by the Michigan Medicaid program to require PA for newly treated patients prescribed all but the two oldest SSRI antidepressants could expose patients to unnecessary risks of treatment failure because the older drugs have higher rates of side effects (agitation and sedation) and drug interactions that raise the blood levels of cardiovascular agents; and the policy could inhibit switching to effective, "nonpreferred" drugs. Several examples of drug classes to avoid (with high heterogeneity in patient response) include antipsychotic agents, antidepressants, medications for bipolar illness and other chronic mental illnesses, and drugs for seizure disorder.⁴⁴

(3) Exclusions from reimbursement of entire categories of effective drugs (such as benzodiazepines) are likely to reduce the quality of care and should be avoided.

(4) Financial or procedural barriers to medication access should be avoided in the most vulnerable, high-risk populations for whom careful selection of medications can prevent severe illness, hospitalization, or death. For example, acutely ill patients with unipolar depression, bipolar illness, or schizophrenia often do not respond to the first or second psychoactive medication regimen because of idiosyncratic differences between patients; it is often impossible to predict which drugs will ultimately be effective. Similarly, such patients have notoriously poor compliance with medication regimens; any changes in medications are likely to disturb fragile social and biologic equilibriums, resulting in expensive exacerbations of illness.⁴⁵ Similar problems exist for patients with AIDS, seizure disorder, osteoporosis, and physical disabilities. The practice of some states (such as Indiana) to exclude the mentally ill from PA is more consistent with protection of the most vulnerable, high-cost patients.

(5) Enforced drug switching in patients with major chronic illnesses should be applied judiciously until evidence exists that such switches are safe and effective and that simple mechanisms exist for switching back to previous therapies in case of treatment failure.

(6) If possible, multiple preferred agents should be provided to reduce the likelihood of limited access to an effective treatment. Excellent applications of this principle include the availability of a large number of preferred generic NSAIDs in the Tennessee Medicaid program and several effective ACE inhibitors in the British Columbia Pharmacare program.⁴⁶

(7) The process for prior authorization should be automated or at least rapid. Rigid, time-consuming barriers to appropriate medications will cause physicians and patients to avoid nonpreferred drugs altogether.⁴⁷ Some physicians refuse to fill out any PA forms because of the time burden and thus "capitulate" by prescribing only preferred agents.⁴⁸ Although many states attempt to minimize delays by reducing turnaround time and written justifications for authorizations of non-preferred drugs, the existence of any formal preapproval process (and the tendency for physicians to follow the path of least resistance) will extinguish many requests for nonpreferred drugs.⁴⁹ Alternatively, the program of RP of ACE inhibitors in British Columbia used computerized claims data to automatically exempt vulnerable populations, such as those with diabetes or congestive heart failure, without requiring any paperwork. To our knowledge, most Medicaid and U.S. managed care plans do not allow such exemptions for high-risk patients.

Medications could be the most comprehensive and cost-effective treatments in the medical armamentarium, but they are not always used judiciously. Increasingly popular cost containment policies promoting the use of inexpensive "preferred drugs" have both risks and benefits. The belief that such policies generally have isolated effects on medication use is not always borne out by the evidence. Rigid policies that target essential classes of medications with heterogeneous patient responses and side effects could reduce appropriate care, adversely affect health status, and cause shifts to other drugs or more expensive types of care. However, harm could be minimized by careful consideration of the degree of inappropriate use of specific high-cost drugs before regulations are implemented and by instituting simple and rapid mechanisms to exempt high-risk patients. Such principles could at times raise drug spending, but they could also reduce nondrug costs.

The current exponential growth in such drug cost containment policies and the limited evidence base justify a substantial investment in research to identify which policies can achieve savings without shifting costs or adversely affecting the health of the most vulnerable Americans.

Editor's Notes

Top Editor's Notes Methods For Systematic Review... Preferred Drugs And Prior... Drug Category Exclusions Increasing Patient Cost Sharing... Discussion And Conclusions Notes

 
Stephen Soumerai is a professor in the Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, in Boston.

This work was funded by AARP. However, the opinions are solely those of the author and do not necessarily represent the views of AARP. The author is also supported by the Harvard Pilgrim Health Care Foundation. He is also indebted to Robert LeCates for technical assistance, Alyce Adams for comments on the literature on prior authorization, David Gross for his contributions as project officer, and the anonymous reviewers of this paper.

Notes

Top Editor's Notes Methods For Systematic Review... Preferred Drugs And Prior... Drug Category Exclusions Increasing Patient Cost Sharing... Discussion And Conclusions Notes

 

1. Kaiser Commission on Medicaid and the Uninsured, "Medicaid: Purchasing Prescription Drugs," Policy Brief, Pub. no. 4025, January 2002, www.kff.org/content/2002/20020213/4025a.pdf (16 October 2003).
2. S.B. Soumerai, H.L. Lipton, and S. Majumdar, "Evaluating and Improving Drug Prescribing," in Pharmacoepidemiology, 3d ed., ed. B. Strom (Chichester: John Wiley and Sons, 2000).
3. U.S. General Accounting Office, Prescription Drugs: FDA Oversight of Direct-to-Consumer Advertising Has Limitations, Pub. no. GAO-03-177 (Washington: GAO, October 2002).
4. Centers for Medicare and Medicaid Services, "CMS Benefit Payments by Major Personal Health Expenditure Service Categories, Calendar Year 2000," in 2002 Data Compendium, September 2002, cms.hhs.gov/researchers/pubs/datacompendium/2002/02pg13.pdf (16 October 2003). On the cost-effectiveness of medications, see Scandinavian Simvastatin Survival Study Group, "Randomised Trial of Cholesterol Lowering in 4,444 Patients with Coronary Heart Disease: The Scandinavian Simvastatin Survival Study," Lancet 344, no. 8934 (1994): 1383–1389[CrossRef][ISI][Medline]; and S.B. Soumerai et al., "Adverse Outcomes of Underuse of Beta-Blockers in Elderly Survivors of Acute Myocardial Infarction," Journal of the American Medical Association 277, no. 2 (1997): 115–121.[Abstract]
5. National Conference of State Legislatures, "Recent Medicaid Prescription Drug Laws and Strategies, 2001–2003," 9 October 2003, www.ncsl.org/programs/health/medicaidrx.htm (11 November 2003); and Kaiser Commission, "Medicaid: Purchasing Prescription Drugs."
6. B. Bruen, "Medicaid and Prescription Drugs: An Overview," October 2000, www.kff.org/content/2000/2202/mcaidandrx.pdf (16 October 2003); and B. Bruen and J. Holahan, "Medicaid Spending Growth Remained Modest in 1998, but Likely Headed Upward," Issue Paper, Pub. no. 2230, February 2001, www.kff.org/content/2001/2230/2230.pdf (16 October 2003).
7. S.B. Soumerai et al., "Payment Restrictions for Prescription Drugs under Medicaid: Effects on Therapy, Cost, and Equity," New England Journal of Medicine 317, no. 9 (1987): 550–556; [Abstract]S.B. Soumerai et al., "Effects of Medicaid Drug-Payment Limits on Admission to Hospitals and Nursing Homes," New England Journal of Medicine 325, no. 15 (1991): 1072–1077; [Abstract]S.B. Soumerai et al., "Effects of Limiting Medicaid Drug-Reimbursement Benefits on the Use of Psychotropic Agents and Acute Mental Health Services by Patients with Schizophrenia," New England Journal of Medicine 331, no. 10 (1994): 650–655[Abstract/Free Full Text]; and R. Tamblyn et al., "Adverse Events Associated with Prescription Drug Cost-Sharing among Poor and Elderly Persons," Journal of the American Medical Association 285, no. 4 (2001): 421–429.[Abstract/Free Full Text]
8. Soumerai et al., "Payment Restrictions for Prescription Drugs"; Soumerai et al., "Effects of Medicaid Drug-Payment Limits"; Soumerai et al., "Effects of Limiting Medicaid Drug-Reimbursement Benefits"; and E.E. Fortess et al., "Utilization of Essential Medications by Vulnerable Elderly after a Drug Benefit Cap: Importance of Mental Disorders, Chronic Pain, and Practice Setting," Journal of the American Geriatrics Society 49, no. 6 (2001): 793–797.[CrossRef][ISI][Medline]
9. Soumerai et al., "Effects of Limiting Medicaid Drug-Reimbursement Benefits."
10. Tamblyn et al., "Adverse Events Associated with Prescription Drug Cost-Sharing."
11. See S.B. Soumerai et al., "A Critical Analysis of Studies of State Drug Reimbursement Policies: Research in Need of Discipline," Milbank Quarterly 71, no. 2 (1993): 217–52.
12. Ibid.
13. Ibid.; and J. Santa, "Oregon’s Approach to Prescription Drugs," slide presentation at Web-assisted audio-conference, "Causes of and Potential Solutions to the High Cost of Health Care," 15 October 2002, Agency for Healthcare Research and Quality, www.ahrq.gov/news/ulp/hicosttele/sess3/santatxt.htm (28 August 2003).
14. Soumerai et al., "A Critical Analysis of Studies."
15. J. Lexchin, "Effects of Restrictive Formularies in the Ambulatory Care Setting," American Journal of Managed Care 8, no. 1 (2001): 69–76.
16. NCSL, "Recent Medicaid Prescription Drug Laws and Strategies, 2001–2003."
17. Ibid.
18. R. Pérez-Peña, "Twenty-two States Limiting Doctors’ Latitude in Medicaid Drugs," New York Times, 16 June 2003.
19. D.M. Gencarelli, "Medicaid Prescription Drug Coverage: State Efforts to Control Costs," National Health Policy Forum Issue Brief no. 790, 10 May 2003, www.nhpf.org/pdfs_ib/IB790%5FStateRx%5F5%2D10%2D03%2Epdf (23 June 2003).
20. R.M. Bagby, A.G. Ryder, and C. Cristi, "Psychosocial and Clinical Predictors of Response to Pharmacotherapy for Depression," Journal of Psychiatry and Neuroscience 27, no. 4 (2002): 250–257.[ISI][Medline]
21. I.D. Glick, "Psychopharmacologic Treatment Strategies for Depression, Bipolar Disorder, and Schizophrenia," Annals of Internal Medicine 134, no. 1 (2001): 47–60.[Abstract/Free Full Text]
22. NCSL, "Recent Medicaid Prescription Drug Laws and Strategies, 2001–2003."
23. B.S. Bloom and J. Jacobs, "Cost Effects of Restricting Cost-Effective Therapy," Medical Care 23, no. 7 (1985): 872–880[CrossRef][ISI][Medline]; and Soumerai et al., "A Critical Analysis of Studies."
24. H.V. Fineberg and L.A. Pearlman, "Surgical Treatment of Peptic Ulcer in the United States: Trends before and after the Introduction of Cimetidine," Lancet 1, no. 8233 (1981): 1305–1307.[CrossRef][ISI][Medline]
25. "Peptic Ulcer Medication Usage: United States," Statistical Bulletin—Metropolitan Insurance Companies 71, no. 4 (1990): 10–17.
26. Fineberg et al., "Surgical Treatment of Peptic Ulcer;" and Soumerai et al., "A Critical Analysis of Studies."
27. W.E. Smalley et al., "Effect of a Prior Authorization Requirement on the Use of Nonsteroidal Anti-inflammatory Drugs by Medicaid Patients," New England Journal of Medicine 332, no. 24 (1995): 1612–1617.[Abstract/Free Full Text]
28. S.B. Soumerai and H.L. Lipton, "Computer-Based Drug Utilization Review: Risk, Benefit, or Boondoggle?" New England Journal of Medicine 332, no. 24 (1995): 1641–1645.[Free Full Text]
29. J.A. Kotzan et al., "Initial Impact of a Medicaid Maintenance Dose Program for H2 Antagonist Prescriptions," Journal of Research in Pharmaceutical Economics 5, no. 1 (1993): 43–58; and J.A. Kotzan et al., "Initial Impact of a Medicaid Prior Authorization Program for NSAID Prescriptions," Journal of Research in Pharmaceutical Economics 5, no. 1 (1993): 25–41.
30. S.B. Soumerai et al., "Withdrawing Payment for Non-Scientific Drug Therapy: Intended and Unexpected Effects of a Large-Scale Natural Experiment," Journal of the American Medical Association 263, no. 6 (1990): 831–839[Abstract]; and Soumerai et al., "A Critical Analysis of Studies."
31. S. Schneeweiss et al., "Impact of Reference-Based Pricing for Angiotensin-Converting-Enzyme Inhibitors on Drug Utilization," Canadian Medical Association Journal 166, no. 6 (2002): 737–745[Abstract/Free Full Text]; and P. Kanavos and U. Reinhardt, "Reference Pricing for Drugs: Is It Compatible with U.S. Health Care?" Health Affairs (May/June 2003): 16–30.
32. Glick, "Psychopharmacologic Treatment Strategies"; and Soumerai et al., "Payment Restrictions."
33. Schneeweiss et al., "Impact of Reference-Based Pricing"; and S. Schneeweiss et al., "Outcomes of Reference Drug Pricing for Angiotensin-Converting Enzyme Inhibitors in British Columbia," New England Journal of Medicine 346, no. 11 (2002): 822–829.[Abstract/Free Full Text]
34. S. Schneeweiss, S. Soumerai, and M. Maclure, "Reference Drug Pricing" (letter), Canadian Medical Association Journal 167, no. 2 (2002): 126–127.[Free Full Text]
35. P.V. Grootendorst, "Impact of Reference-Based Pricing of Nitrates on the Use and Costs of Anti-Anginal Drugs," Canadian Medical Association Journal 165, no. 8 (2001): 1011–1019.[Abstract/Free Full Text]
36. T.K. Hazlet and D.K. Blough, "Health Services Utilization with Reference Drug Pricing of Histamine2 Receptor Antagonists in British Columbia Elderly," Medical Care 40, no. 8 (2002): 640–649.[CrossRef][ISI][Medline]
37. J.K. Marshall et al., "Impact of Reference-Based Pricing for Histamine-2 Receptor Antagonists and Restricted Access for Proton Pump Inhibitors in British Columbia," Canadian Medical Association Journal 166, no. 13 (2002): 1655–1662.[Abstract/Free Full Text]
38. Bloom and Jacobs, "Cost Effects of Restricting Cost-Effective Therapy."
39. Smalley et al., "Effect of a Prior Authorization Requirement"; Kotzan et al., "Initial Impact of a Medicaid Maintenance Dose Program"; and Kotzan et al., "Initial Impact of a Medicaid Prior Authorization Program."
40. Soumerai et al., "Withdrawing Payment."
41. Schneeweiss et al., "Impact of Reference-Based Pricing"; Schneeweiss et al., "Outcomes of Reference Drug Pricing"; Grootendorst, "Impact of Reference-Based Pricing of Nitrates"; and Hazlet et al., "Health Services Utilization."
42. Schneeweiss et al., "Outcomes of Reference Drug Pricing"; and Hazlet et al., "Health Services Utilization."
43. Smalley et al., "Effect of a Prior Authorization Requirement"; and Schneeweiss et al., "Outcomes of Reference Drug Pricing."
44. J.G. Hardman and L.E. Limbird, eds., and A.G. Gilman, consulting ed., Goodman and Gilman’s The Pharmacological Basis of Therapeutics, 10th ed. (New York: McGraw-Hill Professional, 2001); and S. Somers and J. Perkins, "Model Prescription Drug Prior Authorization Process for State Medicaid Programs," April 2003, www.kff.org/content/2003/4104/4104.pdf (28 August 2003).
45. Soumerai et al., "Effects of Limiting Medicaid Drug-Reimbursement Benefits."
46. Smalley et al., "Effect of a Prior Authorization Requirement"; and Schneeweiss et al., "Outcomes of Reference Drug Pricing."
47. Bloom and Jacobs, "Cost Effects of Restricting Cost-Effective Therapy."
48. N.J. MacKinnon and R. Kimur, "Prior Authorization Programs: A Critical Review of the Literature," Journal of Managed Care Pharmacy 7, no. 4 (2001): 297–302.
49. Soumerai et al., "A Critical Analysis of Studies."

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