Quality of life in depression scale (QLDS). Development, reliability, validity, responsiveness and application.

Area of Science:

• Psychometric evaluation
• Clinical psychology
• Quality of life assessment

Background:

• Quality of life is crucial in managing depression.
• Existing measures may not fully capture the needs of depressed individuals.
• The needs model of quality of life provides a framework for scale development.

Purpose of the Study:

• To describe the joint development of the Dutch and English versions of the Quality of Life in Depression Scale (QLDS).
• To evaluate the reliability, internal consistency, and validity of the QLDS.
• To assess the scale's responsiveness to treatment in major depression.

Main Methods:

• Development of the QLDS based on the Hunt and McKenna needs model.
• Assessment of test-retest reliability and internal consistency (Cronbach's alpha).
• Evaluation of convergent validity against well-being measures and depression severity (Hamilton Rating Scale for Depression).
• Responsiveness testing in a fluoxetine treatment study for major depression.

Main Results:

• High test-retest correlation coefficients (0.94 UK, 0.87 Netherlands).
• Excellent internal consistency (alpha 0.95 UK, 0.92 Netherlands).
• Highly acceptable validity, correlating with well-being and depression severity.
• QLDS demonstrated responsiveness to change during fluoxetine treatment in 540 patients.

Conclusions:

• The QLDS is a reliable, valid, and user-friendly instrument for assessing quality of life in depression.
• The scale shows wide applicability and is undergoing international validation.
• The QLDS is a sensitive measure for detecting treatment-induced changes in quality of life for depressed patients.