Table 1

Taxonomy of PROs Used in Clinical Trials

Attribute
Types

Intended use of the measure
• To define entry criteria for study populations
• To evaluate efficacy
• To evaluate adverse events
Concepts measured
• Overall health status
• Symptoms/signs, individually or as a syndrome associated with a medical condition
• Functional status (physical, psychological or social)
• Health perceptions (e.g., self-rating of health or worry about condition)
• Satisfaction with treatment or preference for treatment
• Adherence to medical treatment
Number of items
• Single item for single concept
• Multiple items for single concept
• Multiple items for multiple domains within a concept
Intended measurement population or condition
• Generic
• Condition-specific
• Population-specific
Mode of data collection
• Interviewer-administered
• Self-administered, with or without supervision
• Computer-administered or computer-assisted
• Interactively administered (e.g., interactive voice response systems or Web-based systems)
Timing and frequency of administration
• As events occur
• At regular intervals throughout a study
• Baseline and end of treatment
Types of scores
• Single rating on a single concept (e.g., pain severity)
• Index – single score combining multiple ratings of related domains or independent concepts
• Profile – multiple uncombined scores of multiple-related domains
• Battery – multiple uncombined scores of independent concepts
• Composite – an index, profile, or battery
Weighting of items or concepts
• All items and domains are equally weighted
• Items are assigned variable weights
• Domains are assigned variable weights
Response options
• See Table 2 for examples of response options (types of PRO scales)

U.S. Department of Health and Human Services FDA Center for Drug Evaluation and Research et al. Health and Quality of Life Outcomes 2006 4:79   doi:10.1186/1477-7525-4-79