Pharmacoeconomic Model of Serotonin Reuptake Inhibitors
This article summarizes the responses provided by participants in two roundtable discussions to a pharmacoeconomic model of the class of serotonin reuptake inhibitors (SRIs).
A decision-analytic model was developed to examine the potential impact of differences in adverse drug reactions (ADRs) reported in the prescribing information of eight currently marketed SRIs on the expected cost of treatment and to provide preliminary data that may assist P&T committees in making decisions about this class (Table 1). The discussants (Table 2) included representatives of managed care organizations (MCOs) and pharmacy benefit managers with extensive experience in the P&T decision-making process.
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Sponsored by Forest Pharmaceuticals, the roundtables were held on March 31, 2004 in San Francisco and in Washington, DC, in conjunction with the P&T Society’s annual meeting on April 21, 2004. Since then, the model discussed at the meetings has been published. The model was refined, and its application by P&T committees was discussed in the February 2005 issue of P&T.
AMCP FORMAT
The Sullivan model is intended to be used together with a comprehensive dossier submitted by pharmaceutical companies to health plans using the format devised by the Foundation of the Academy of Managed Care Pharmacy (AMCP). The participants said many pharmaceutical companies submit dossiers to P&T committees, but few scrupulously follow the AMCP format. One MCO official reported devising a checklist to identify missing components, allowing for the provision of feedback to the submitting company. Roundtable members reported that, on learning about the MCO’s expectations and realizing that P&T committees will use every component of the AMCP-format dossier, pharmaceutical companies have tended to provide the missing items. The component most often noted as missing is the pharmacoeconomic model.
One participant pointed out that in a one-person department, a pharmacy director often lacks time to order AMCP dossiers and examine them while still attending to other duties. The complete dossier contains enough material to be overwhelming in some cases. Another participant suggested that if the dossier were provided in tabbed binders, recipients could select the portions relevant to the particular needs of their P&T committee. Many pharmaceutical companies provide the dossier in a CD ROM format, allowing for flexibility in printing and distribution. buy generic cialis
The organizations represented at the roundtable varied considerably in the design of the pharmacy benefits they administer, the composition and meeting frequency of their P&T committees, and in the weights they attach to the clinical and financial data found within the AMCP dossier. Some committees evaluate a drug solely on its clinical merits, whereas others give equal weight to financial considerations. For example, a consultant for a long-term care P&T committee reported using an entirely clinically driven process, under which drugs for the elderly are categorized as preferred, acceptable, or unacceptable. Likewise, a representative of a Medicaid MCO reported that its P&T committee rarely discusses financial considerations; clinical issues dominate the discussion there, based on committee members’ presentations on products.
At one northeastern health plan, however, negotiations within the committee include concurrent discussion of clinical and economic issues. Pharmacists on that P&T committee prepare monographs about particular drug groups or classes. Subcommittees of specialists in particular areas make recommendations to the main committee, which is free to accept
or reject them. That committee, despite observations by the pharmacy director that the products will adversely affect the pharmacy budget, routinely has accepted clinically superior drugs. Another individual represented a health plan P&T committee that gives equal consideration to financial and clinical problems. One participant noted that a fixed-dollar cap on subscribers’ pharmacy benefits often affects patient willingness to accept prescriptions for any “third-tier” drugs that count toward those limits.
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One participant remarked that if pharmaceutical companies desire to command the attention of a P&T committee, information should be presented about absolute risk reduction (ARR) and the corresponding number needed to treat (NNT) associated with use of a drug. This attendee’s main point was that relative risk reduction information can sometimes be misleading or can overstate the apparent importance of a finding when the ARR is small. For example, cutting the incidence of a side effect or adverse clinical outcome during a course of treatment in half (relative reduction of 50%) sounds impressive, but if the 50% reduction is a reduction of an absolute rate of 1.0% down to 0.5%, the relative risk might be misleading as the absolute advantage is small. The corresponding NNT is equal to 1/ARR. In this case, 200 patients would have to be treated to prevent one bad outcome. Inclusion of the NNT often is very useful in making P&T decisions.
Participants also pointed out that presentations should emphasize clinically significant differences of a treatment or among treatments, not merely statistical significance. P&T decisions are based, first, on clinical significance and only secondarily on economic considerations. In that context, the Sullivan (2004) model of differences in the incidence, type, and costs of adverse drug reactions (ADRs) associated with the use of different SRIs may be clinically significant to patients and may provide potentially useful information on the financial effects of these differences. Head-to-head clinical trials have not been done to determine clinically or statistically significant differences in ADR incidence and cost among agents, thus necessitating that these projections be based on the package insert data. Therefore, sensitivity analysis, when it allowed the parameters to be varied, was deemed extremely helpful by the authors.
