Intervention Research Establishing Fidelity of the Independent Variable in Nursing Clinical Trials Karen Farchaus Stein 4 Judy T. Sargent 4 Nicholas Rafaels b Background: Internal validity of a randomized clinical trial of a nursing intervention is dependent on intervention fidelity. Although several methods have been developed, evaluating audio or audiovisual tapes for prescribed and proscribed interventionist behaviors is considered the gold standard test of treatment fidelity. This approach requires development of a psychometrically sound instru- ment to meaningfully categorize and quantify intervention- ist behaviors. b Objective: To outline critical steps necessary to develop a treatment fidelity instrument. b Methods: A comprehensive literature review was conducted to determine procedures used by other researchers. The literature review produced five quantitative studies of treatment fidelity, all in the field of psychotherapy, and two replication studies. A synthesis of methodologies across studies combined with researchers’ experiences resulted in identification of the steps necessary to develop a treatment fidelity measure. b Results: Seven sequential steps were identified as essential to the development of a valid and reliable measure of treatment fidelity. These steps include (a) identification of the essential elements of the experimental and control treatment modalities; (b) construction of scale items; (c) development of item scaling; (d) identification of the units for coding; (e) item testing and revision; (f) specification of rater qualifications and development of rater training program; and (g) development and completion of pilot testing to test psychometric properties. Development of the Possibilities Project Psychotherapy Coding Questionnaire is described as an illustration of the seven-step process. b Discussion: The results show the essential steps that are unique to the development of treatment fidelity measures and show the feasibility of using these steps to construct a psychometrically sound treatment-specific fidelity measure. b Key Words: internal validity & intervention fidelity & randomized clinical trials R andomized clinical trials (RCTs) are vital in advanc- ing effective new nursing interventions. In RCTs, the efficacy of the experimental intervention is established through comparison of patient outcomes between pre- established groups, including one group who received the experimental treatment and one who received the control or comparison treatment. The nature of many experimental nursing interventions is that they are flexible, dynamic, and individualized to be sensitive and responsive to the unique characteristics of the participant. Although this approach is essential to ensure clinically meaningful and relevant interventions, internal validity of the trial is dependent on the systematic and reliable delivery of the independent treatment variable (Calsyn, 2000). Hence, methods to establish reliable delivery of the treatment intervention ob- jectively are central to the integrity of any randomized trial. Reliable and competent delivery of an experimental treatment by the interventionist is referred to in the literature as intervention fidelity (Moncher & Prinz, 1991; Ogrodniczuk & Piper, 1999; Santacroce, Maccarelli, & Grey, 2004). Intervention fidelity has two core compo- nents: adherence and competence. Adherence is the most basic and is the extent to which the interventionists’ behaviors conform to the treatment protocol. Adherence is focused on the quantity of prescribed behaviors that are delivered in a treatment session or course, and compares the quantity of generic interventionist behaviors (common across psychotherapy) and behaviors that are proscribed by the protocol. The competence component is more complex and is focused on the interventionist’s skillfulness in the delivery of the intervention. In recent years, important strategies have been used to improve intervention fidelity, including the use of treatment manuals, formal training of interventionists, Nursing Research . January/February 2007 . Vol 56, No 1, 54–62 54 Nursing Research January/February 2007 Vol 56, No 1 Karen Farchaus Stein, PhD, RN, FAAN, is Associate Professor; and Judy T. Sargent, MS, RN, CS, is Doctoral Student and Research Assistant, School of Nursing, University of Michigan, Ann Arbor. Nicholas Rafaels, MS, is Programmer/Data Analyst, Division of Allergy and Clinical Immunology, Department of Medicine, The Johns Hopkins University, Baltimore, Maryland. Copyr ight © Lippincott Williams & Wilkins. Unauthor iz ed reproduction of this article is prohibited.