Age, sex, and symptom intensity influence test taking parameters on functional patient-reported outcomes

Item response theory-based patient-reported outcomes such as the Activity Measure for Post Acute Care Computerized Adaptive Test are gaining use because of their flexibility and ease of administration. Their psychometric properties are being explored, but little is known about how respondent characteristics may impact precision. The goal of this study was, therefore, to assess the effects of age, sex, and symptom intensity on respondents' test taking behaviors and scores.

Three hundred eleven adults with late-stage lung cancer were consecutively enrolled between April 2008 and April 2009. Demographics and comorbidities were abstracted from their electronic medical records. The participants were followed on a 3- to 4-wk basis by telephonic interviews that involved administration of the Activity Measure for Post Acute Care Computerized Adaptive Test, followed by numerical rating scales scoring of their pain, fatigue, and dyspnea.

In more than 2538 computerized adaptive test (CAT) sessions, three findings were prominent. First, the women and the older patients took longer to complete CAT sessions, were more likely to skip items, and produced scores with larger standard errors. Second, the respondents with higher levels of dyspnea and fatigue, but not pain, completed their CAT sessions more rapidly and were less likely to skip items. Third, fatigue and dyspnea interact with age but not sex to influence CAT duration and skip count.

The findings of this study suggest that certain common clinical populations, for example, women, geriatric patients, and patients with intense symptoms, differ systematically in the time they are willing to devote to testing and the precision of their responses. The latter finding, unstable precision, is unlikely to be CAT specific and has implications for the interpretation of the scores of the Activity Measure for Post Acute Care Computerized Adaptive Test and other patient-reported outcomes.