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Table 3 Common Reasons for Changing PRO Instruments During Initial Development

From: Guidance for industry: patient-reported outcome measures: use in medical product development to support labeling claims: draft guidance

Item Property Reason for Change or Deletion
Clarity or relevance • Reported as not relevant by a large segment of the population of interest
• Generates an unacceptably large amount of missing data points
• Generates many questions or requests for clarification from patients as they complete the PRO instrument
• Patients interpret items and responses in a way that is inconsistent with the conceptual framework
Response range • A high percent of patients respond at the floor (worst end of the response scale) or ceiling (optimal end of the response scale)
• Patients note that none of the response choices apply to them
• Item means are highly skewed
Variability • All patients give the same answer (i.e., no variance)
• Most patients choose only one of the response choices
• Differences among patients are not detected when important differences are known
Reproducibility • Unstable scores over time when there is no logical reason for variation from one assessment to the next
Inter-item correlation • Item uncorrelated with other items in the same concept of interest
Ability to detect change • Item is nonresponsive (i.e., does not change when there is a known change in the concepts of interest)
Item discrimination • Item is highly correlated with measures of concepts other than the one it is intended to measure
Redundancy • Item duplicates information collected with other items that have equal or better measurement properties