Measuring improvement in depression in cancer patients: a 50% drop on the self-rated SCL-20 compared with a diagnostic interview☆☆☆★★★
Received 23 August 2009; accepted 5 January 2010. published online 25 February 2010.
Abstract
Objective
To determine the validity of a 50% drop in the 20-item Symptom Checklist Depression Scale (SCL-20) score against the “gold standard” of no longer meeting criteria for major depression as assessed using a diagnostic interview in an outpatient cancer population and also to examine the validity of other potential cut-offs (i.e., percentage drops).
Materials and Methods
Secondary analysis of data from a randomized trial which compared collaborative care with usual care for cancer patients with major depression. A total of 194 trial participants who had both SCL-20 scores and depression diagnoses on the Structured Clinical Interview for DSM-IV at both baseline and at 12-week outcome formed the analyzed sample.
Results
A 50% reduction in the SCL-20 score from baseline to 12 weeks correctly identified the patients who no longer met criteria for major depression in 153 (78.9%) of 194 (95% CI 73.1% to 84.6%) cases. Most of those misclassified had not achieved a 50% reduction in SCL-20 score despite no longer meeting criteria for major depression. Examination of the performance of percentage drops other than 50% on the SCL-20 using a receiver operating characteristics (ROC) curve and histogram of misclassification suggested that the 50% drop was best if both a low overall misclassification rate and the minimizing of false positives of improvement were required.
Conclusions
A 50% reduction in the SCL-20 score performs well as a conservative measure of change in depression status in cancer patients.
aPsychological Medicine Research, University of Edinburgh Cancer Research Centre, School of Molecular and Clinical Medicine, University of Edinburgh, Edinburgh EH4 2XR, Scotland, UK
bPublic Health Sciences Section, Division of Community Health Sciences, The University of Edinburgh Medical School, Edinburgh EH8 9AG, Scotland, UK
☆ Work performed at Psychological Medicine Research, The University of Edinburgh Cancer Research Centre, School of Molecular and Clinical Medicine, University of Edinburgh and the Edinburgh NHS Cancer Centre, Edinburgh, Scotland, UK.
ABSTRACT