National Drug Formulary review of statin therapeutic group using the multiattribute scoring tool

Abstract

Purpose

HMG-CoA reductase inhibitors (statins) are extensively used in treating hypercholesterolemia. The statins available in Malaysia include atorvastatin, lovastatin, pravastatin, rosuvastatin, simvastatin, and fluvastatin. Over the years, they have accumulated in the National Drug Formulary; hence, the need for review. Effective selection of the best drugs to remain in the formulary can become complex due to the multiple drug attributes involved, and is made worse by the limited time and resources available. The multiattribute scoring tool (MAST) systematizes the evaluation of the drug attributes to facilitate the drug selection process. In this study, a MAST framework was developed to rank the statins based on their utilities or benefits.

Methods

Published literature on multicriteria decision analysis (MCDA) were studied and five sessions of expert group discussions were conducted to build the MAST framework and to review the evidence. The attributes identified and selected for analysis were efficacy (clinical efficacy, clinical endpoints), safety (drug interactions, serious side effects and documentation), drug applicability (drug strength/formulation, indications, dose frequency, side effects, food–drug interactions, and dose adjustments), and cost. The average weights assigned by the members for efficacy, safety, drug applicability and cost were 32.6%, 26.2%, 24.1%, and 17.1%, respectively. The utility values of the attributes were scored based on the published evidence or/and agreements during the group discussions. The attribute scores were added up to provide the total utility score.

Results

Using the MAST, the six statins under review were successfully scored and ranked. Atorvastatin scored the highest total utility score (TUS) of 84.48, followed by simvastatin (83.11). Atorvastatin and simvastatin scored consistently high, even before drug costs were included. The low scores on the side effects for atorvastatin were compensated for by the higher scores on the clinical endpoints resulting in a higher TUS for atorvastatin. Fluvastatin recorded the lowest TUS.

Conclusion

The multiattribute scoring tool was successfully applied to organize decision variables in reviewing statins for the formulary. Based on the TUS, atorvastatin is recommended to remain in the formulary and be considered as first-line in the treatment of hypercholesterolemia.

Keywords:

• multicriteria decision analysis
• utility score
• drug attributes
• drug selection

Supplementary material

Assignments of attribute and factor weightages for multiattribute scoring tool (MAST)

Introduction: in drug selection, degree of importance of each factor/selection criteria being considered could vary. For some individuals efficacy/effectiveness may be more important than costs, for example. Thus, there is a need to allocate weights to the factors/selection criteria based on their importance. Together with individual drug values, the assigned criteria weights will contribute to the final score calculation.

Instructions: for this exercise, we need you to weigh the drug factors/selection criteria below by allocating percentage (%) to the factors/selection criteria listed (1a to 4a). The more important the criterion is, the more % should be allocated to it.

Allocation of weightages can be done in two easy steps.

1. In the boxes marked *, allocate % to the four attributes listed (efficacy/effectiveness, safety, drug applicability, and economics). Higher percentages should be given to attributes that you think are more important. For example if you think that efficacy/effectiveness is two times more important than economics, when economics is allocated 20%, efficacy/effectiveness should be given 40%. Percentages given to the four attributes should add up to 100%.

2. In the boxes marked #, allocate % for the corresponding factors/selection criteria. The % allocated for the factors of each attribute should total up to the % given to the particular attribute already allocated in Step 1.

For example if you have given 40% for efficacy/effectiveness and think that clinical efficacy is more important between the two factors, you may want to allocate 25% for clinical efficacy and 15% for effect on clinical endpoints.

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THANK YOU FOR YOUR TIME. IT IS HIGHLY APPRECIATED

Table S1 Clinical trials included in the analysis

Acknowledgments

We would like to thank the Director General of Health, Malaysia, for granting permission to publish this study. We are also grateful to the National Institute of Health (NIH), Ministry of Health, Malaysia, for providing financial assistance through the NIH grant (NMRR-12-77-10772). Our special thanks is due to the members of the Drug Scoring Technical Committee; Anis Talib, Aznida Abd Aziz, Azuwana Supian, Noraini Saari, Rosliza Lajis, Haarathi Chandriah, Hariana Haris, Hayati Alwani, and Lim Ming Tsuey for their time, input, and views, as well as cooperation and patience in the course of building the tool framework and gathering evidence to support the tool application.

Disclosure

The authors declare that they have no competing interests in this work.