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Common Reasons for Changing PRO Instruments During Initial Development |
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| Item Property |
Reason for Change or Deletion |
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| 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 |
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 |
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