The Distress Thermometer as an ultra-short screening tool: a first validation study for mixed-cancer outpatients in Singapore.
INTRODUCTION
Research has shown that single-item tools, like the Distress Thermometer (DT), are comparable to longer ones, like the Hospital Anxiety and Depression Scale (HADS). In this study, we tested the validity of the DT in a population of Singapore cancer outpatients, and determined the cut-off scores on the DT for clinically relevant distress and an impaired quality of life (QOL). We also documented the prevalence of anxiety, depression, and QOL impairments in this population.


METHODS
One hundred and five patients (Mdn age=51-60years, 64% female, and 71% Chinese) diagnosed with various cancers participated in this study. They completed a standard socio-demographic form, the DT and the Problem List, the HADS, and the EuroQOL Quality of Life Scale (EQ-5D).


RESULTS
Almost a third of patients had clinically significant emotional distress, with 15%-16% having probable levels of anxiety and depression. Almost half (41%-55%) had an impaired QOL compared to Singapore population norms. Receiver operating characteristic curve analyses identified an area under the curve of 0.89 (SE=0.36, 95% CI [0.82, 0.96], p<.001) when compared to the HADS cut-off score of 15. A cut-off score of 5 on the DT had the best sensitivity (0.88) and specificity (0.81). Participants above the DT cut-off score of 5 reported significantly more emotional problems (worry, nervousness, depression, sadness), insurance/finance-related problems, and sleep problems. They also scored significantly lower on EQ-5D, with more QOL impairments in the domains of carrying out their usual activities and anxiety/depression.


CONCLUSION
Levels of distress, anxiety, depression, and QOL impairments are high in this population. The DT was found to be a valid tool for distress screening in the Singapore cancer population, with a recommended cut-off score of 5.