Screening for rehabilitation needs in newly diagnosed breast cancer patients: exploring psychometric properties of the National Comprehensive Cancer Network® (NCCN®) Distress Thermometer and Problem List

Background Identifying and managing distress in breast cancer patients is a crucial element of adequate rehabilitation. Immediately after diagnosis, a brief instrument such as the Distress Thermometer has the potential to aid early assessment of distress. Similarly, the accompanying Problem List can aid identification of sources of distress. The aim of this study was to determine cut-off scores of the Distress Thermometer indicating patients with clinically significant impaired functioning which is likely to reflect distress, to investigate its validity, and explore the measurement properties of the Problem List. Methodology 634 Swedish patients participating in the ReScreen​ intervention study [NCT03434717] were included. ROC curve analysis was performed to explore cut-off scores of the Distress Thermometer in relation to emotional, social, cognitive functioning, and global quality of life subscales of the QLQ-C30. The factor structure of the Problem List was assessed using Confirmatory Factor Analysis. Content validity of the Distress Thermometer was assessed in relation to resilience, assessed using the Connor-Davidson Resilience Scale. Convergent validity of the Problem List was investigated in relation to resilience and relevant QLQ-C30 subscales. Results The Distress Thermometer had acceptable accuracy in identifying clinically significant impaired cognitive functioning and global quality of life and excellent relative to emotional and social functioning. A cut-off on the Distress Thermometer between 4 and 5 was found to best balance sensitivity and specificity relative to impaired emotional and social functioning. The Problem List had acceptable model fit. The Distress Thermometer had good content validity and the Problem List convergent validity. Conclusions The Distress Thermometer and the Problem List have the potential to aid screening for newly diagnosed breast cancer patients with clinically significant impaired functioning. To ensure the responses accurately reflect the patient’s life, these tools should be used alongside a clinical interview when assessing dysfunction. A cut-off score on the Distress Thermometer between 4 and 5 best balances false negatives and false positives relative to impaired emotional and social functioning. However, before it is implemented in clinical practice, further validation in external and large cohorts is needed. A qualitative evaluation of the instrument would contribute to its utility.