Developing brief scales for use in clinical practice: The reliability and validity of single-item self-report measures of depression symptom severity, psychosocial impairment due to depression, and quality of life

Objective: Reliable, valid, user-friendly measurement is necessary to successfully implement an outcomes evaluation program in clinical practice. Self-report questionnaires, which generally correlate highly with clinician ratings, are a cost-effective assessment option. However, even self-administered questionnaires can be burdensome to patients because many are lengthy. Consequently, we developed and determined the reliability and validity of ultra-brief, single-item assessments of 3 domains important to consider when treating depressed patients: symptom severity, psychosocial functioning, and quality of life. Method: In the first study (conducted June 1997 to March 2002), 1278 psychiatric outpatients with various DSM-IV diagnoses completed single-item assessments of psychosocial functioning and quality of life as well as more detailed measures of these constructs. In the second study (conducted August 2003 to July 2004), 562 psychiatric outpatients who were in ongoing treatment for a DSM-IV major depressive episode completed a depression symptom scale and a measure of global severity of depression. Results: The test-retest reliability of the psychosocial functioning and quality-of-life items was high. The single-item measures of symptom severity, psychosocial functioning, and quality of life were significantly correlated with the total scores and individual item scores of longer measures of the same constructs (p < .001). The single-item measures significantly discriminated between depressed patients in full remission, in partial remission, and in a current depressive episode (p < .001). Conclusion: These studies provide evidence of the reliability and validity of single-item measures of symptom severity, psychosocial functioning, and quality of life. Very brief measures, such as the ones described in the present report, are not burdensome for patients to complete and can be easily incorporated into a busy clinical practice in order to collect data on treatment effectiveness.