Purpose: The specific concerns of people with low platelet counts (thrombocytopenia) have not been characterized well in the literature and as a result proper measurement of patient-reported concerns is lacking. We report on the development and validation of questions specifically targeted to patients with thrombocytopenia that can be added to the more general concerns in the Functional Assessment of Cancer Therapy-General.
Materials and methods: An 18-item FACT-Thrombocytopenia Subscale (ThS) was rated and evaluated by thrombocytopenic patients at baseline during a validation study of 40 thrombocytopenic and 43 nonthrombocytopenic cancer patients. To evaluate responsiveness, patients completed a battery of self-report measures including the FACT-Th and were followed up for change in platelet count over 2 weeks.
Results: All subscales and aggregated scores showed high internal consistency at initial assessment and at retesting. Convergent and divergent validity were demonstrated by predicted relationships between FACT-Th subscales and mood, mental and physical component scores of the SF-36, and social desirability. The ThS differentiated patients with low platelets from those with normal platelet counts and good performance from poor performance status patients.
Conclusion: The FACT-Th is a reliable and valid measure for assessing the impact of thrombocytopenia on patients' lives. It can distinguish cancer patients with and without thrombocytopenia and is responsive to increase in platelet count over time. The FACT-Th may therefore prove useful as a measure of self-reported symptoms and concerns related to thrombocytopenia in clinical trials evaluating new pharmacologic agents and/or platelet transfusion practice.