Validation of the Distress Thermometer in a Swedish population of oncology patients; accuracy of changes during six months.

Purpose: To validate the Swedish version of the Distress Thermometer (DT) against the Hospital Anxiety and Depression Scale (HADS) for screening of distress and to explore how well DT measures changes of distress during six months in a population of heterogeneous oncology patients.

Methods: The DT was translated into Swedish according to the forward- and back-translation procedure. HADS total score ≥15 was used as gold standard. Consecutive patients were invited to participate at their first visit to the Oncology department. The HADS and the DT were completed at baseline and after 1, 3 and 6 months.

Results: 462 baseline and 321 six-month assessments were completed. The patients had a variety of cancer diagnoses (n = 42). Most patients (95%) received active treatment. The DT compared favourably with the HADS. The area under the curve was 0.86 (95% CI, 0.82-0.90). DT ≥ 4 showed a sensitivity of 87%, a specificity of 73%, a positive predictive value (PPV) of 52% and a negative predictive value (NPV) of 95% at baseline. The results from the 1, 3 and 6 months assessments were equivalent baseline results. The DT means changed in the same direction as HADS at all points of assessment. Patients with distress reported statistically significantly more problems in all categories on the associated 'Problem List' compared to non-distressed patients.

Conclusion: The Swedish version of the DT with a score ≥4 is valid for screening of distress in heterogeneous oncology patients. Its ability to measure changes in distress over time is comparable to HADS.