AIMS: FDA’s patient-focused drug development draft guidance suggests a decision process to determine the need for de-novo instrument development and proposes methods to support modification of existing instruments that conform to good measurement principles. Papadopoulos et al. (2020) also described guidelines for evaluating content validity of an existing clinical outcome assessment for a new context/target patient population; including conceptual match, input from target population, instrument content, and modifications. These methodologies can be especially beneficial when developing instruments in areas where there may be a scarcity of patients available for instrument development activities, such as in rare disease populations or diseases impacted by seasonality with limited patient access. Here we describe steps involved in modifying an existing influenza symptom assessment instrument (Osborne, 2011), for use in individuals with RSV infection, a seasonal infectious disease.
METHODS: As a core constellation of symptoms is common to both RSV and influenza, the Influenza Intensity and Impact Questionnaire (Flu-iiQ) a well-validated 25-item PROM, was selected for modification; informed by conceptual mapping of instrument content to input from three clinicians and available literature. Combined concept elicitation (CE)/cognitive debriefing (CD) interviews with laboratory-confirmed RSV patients were conducted to confirm content validity and optimize instrument wording.
RESULTS: Concepts clinically important in describing RSV infection but not included in the Flu-iiQ were added (e.g., wheezing, cough with phlegm, shortness of breath) and irrelevant items were removed (e.g., neck pain and impact on others). Findings from 20 RSV patient interviews (aged: 26-78; 70% female) confirmed the draft RSV Infection, Intensity and Impact Questionnaire (RSV-iiiQ) items accurately reflected the patient experience of RSV infection symptom severity and impact. Only minor revisions to question wording were suggested. The RSV-iiiQ consists of 29 items with four hypothesized domains: respiratory and systemic symptoms, and functional and emotional impact.
CONCLUSION: Creation of the RSV-iiiQ is aligned with recent recommendations for modifying existing PROMs. The RSV-iiiQ is fit for purpose in an adult RSV patient population and incorporates relevant items from the Flu-iiQ. Modification offered efficiencies through conduct of split CE/CD interviews reducing sample size, limited required new item generation, and reduced timelines. Preliminary psychometric evaluation is underway.
