Development of the Flu-PRO: A patient-reported outcome (PRO) instrument to evaluate symptoms of influenza

John H. Powers*, M. Lourdes Guerrero, Nancy Kline Leidy, Mary P. Fairchok, Alice Rosenberg, Andrés Hernández, Sonja Stringer, Christina Schofield, Patricia Rodríguez-Zulueta, Katherine Kim, Patrick J. Danaher, Hilda Ortega-Gallegos, Elizabeth Dansie Bacci, Nathaniel Stepp, Arturo Galindo-Fraga, Kristina St Clair, Michael Rajnik, Erin A. McDonough, Michelande Ridoré, John C. ArnoldEugene V. Millar, Guillermo M. Ruiz-Palacios

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


Background: To develop content validity of a comprehensive patient-reported outcome (PRO) measure following current best scientific methodology to standardize assessment of influenza (flu) symptoms in clinical research. Methods: Stage I (Concept Elicitation): 1:1 telephone interviews with influenza-positive adults (≥18 years) in the US and Mexico within 7 days of diagnosis. Participants described symptom type, character, severity, and duration. Content analysis identified themes and developed the draft Flu-PRO instrument. Stage II (Cognitive Interviewing): The Flu-PRO was administered to a unique set of influenza-positive adults within 14 days of diagnosis; telephone interviews addressed completeness, respondent interpretation of items and ease of use. Results: Samples: Stage I: N = 46 adults (16 US, 30 Mexico); mean (SD) age: 38 (19), 39 (14) years; % female: 56 %, 73 %; race: 69 % White, 97 % Mestizo. Stage II: N = 34 adults (12 US, 22 Mexico); age: 37 (14), 39 (11) years; % female: 50 %, 50 %; race: 58 % White, 100 % Mestizo. Symptoms: Symptoms identified by >50 %: coughing, weak or tired, throat symptoms, congestion, headache, weakness, sweating, chills, general discomfort, runny nose, chest (trouble breathing), difficulty sleeping, and body aches or pains. No new content was uncovered during Stage II; participants easily understood the instrument. Conclusions: Results show the 37-item Flu-PRO is a content valid measure of influenza symptoms in adults with a confirmed diagnosis of influenza. Research is underway to evaluate the suitability of the instrument for children and adolescents. This work can form the basis for future quantitative tests of reliability, validity, and responsiveness to evaluate the measurement properties of Flu-PRO for use in clinical trials and epidemiology studies.

Original languageEnglish
Article number1
JournalBMC Infectious Diseases
Issue number1
StatePublished - 5 Jan 2016
Externally publishedYes


  • Content validity
  • Endpoints
  • Influenza
  • Outcome assessments
  • Patient-reported outcomes
  • Symptoms


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