Conceptual Development of a Measure to Assess Pharmacists' Knowledge of Herbal and Dietary Supplements

Article excerpt

Objectives. To describe the conceptual development of a measure for assessing pharmacist knowledge of herbal and dietary supplements.

Methods. A standardized approach to constructing a multiple-choice competency examination following 8 pre-specified criteria (eg, specifying the target spectrum of herbal and dietary supplements) was used to create an item bank. The quality of each item was evaluated by 5 herbal and dietary supplement content experts based on specific criteria in 3 rounds of review.

Results. From 122 initial items, 56 items were retained for the item bank representing 4 content areas: efficacy/effectiveness, safety, drug-supplement interactions, and regulation. The experts tended to agree that the constructed items represented a wide range of difficulty.

Conclusion. The initial development of a conceptually based item bank/measure of pharmacist herbal and dietary supplement knowledge lays the groundwork for a large-scale validation study. The measure should be useful as a standalone tool and as a component of a knowledge, attitude, and behavior survey for the assessment of pharmacist traits related to herbal and dietary supplements.

Keywords: knowledge, herbal supplements, dietary supplements, pharmacists, standardized examination

INTRODUCTION

The marketing of herbal and dietary supplements has led to dramatic growth in patient use of these products in the last 2 decades. (1-4) As health care professionals whose expertise focuses on pharmacotherapy, pharmacists have an important role in evaluating the safety, efficacy, and effectiveness of herbal and dietary supplement products and guiding patients concerning their appropriate use. (5) However, few studies have investigated pharmacists' knowledge level of herbal and dietary supplements and the extent to which pharmacist knowledge and attitudes towards such products contribute to patient counseling.

Researchers in the field of health care have a tradition of developing and conducting knowledge, attitude, and behavior surveys to gather information, evaluate current practice, and effect curricular refinement. (6) A review of knowledge, attitude, and behavior studies reported that pharmacists perceived they did not possess sufficient knowledge of herbal and dietary supplements. (7) Problematically, there was little evidence to support the availability of conceptually based, validated measures to assess a pharmacist's knowledge concerning herbal and dietary supplements, either as a standalone measure or within the context of a knowledge, attitude, and behavior survey. The purpose of this study was to report the initial development of a measure to assess pharmacist knowledge of herbal and dietary supplements. This represents part of a larger study to develop and validate measures of pharmacists' knowledge, attitude, and counseling on herbal and dietary supplements, which will be used to evaluate the interrelationships between these traits/constructs of interest.

A survey instrument that measures knowledge is typically created to capture respondent knowledge and understanding of scientific and clinical content areas. (6) A format, such as multiple-choice or true/false items, provides a structure for a metric that is used to assess an individual's total score. The score is intended to represent the participant's actual knowledge. Regardless of the type of item structure, there is always a best or most correct answer for each item on a knowledge measure. The advantage of using multiple-choice items over true/false items is that multiple-choice items incur less chance of "blind guessing," which refers to the situation where there is an equal probability of a respondent endorsing each option, where the fewer the options, the higher the likelihood that a respondent's guess will result in the correct answer. Multiple-choice items also demonstrate certain response patterns that are more informative than a dichotomous scoring structure (ie, scoring "1" for choosing the keyed option and scoring "0" for selecting any incorrect distractor options). …