Making clinicians lives easier: Guidance on use of the QIDS self-report in place of the MADRS

Background: The ability to convert total scores from one scale to another facilitates the interpretation of research findings and facilitates the use of systematic measurement in clinical practice. Methods: Item Response Theory methods were used to convert total scores between the 16-item Quick Inventory of Depressive Symptomatology (QIDS-SR₁₆) and the Montgomery Asberg Depression Rating Scale (MADRS) total scores. Data were obtained from a sample of 233 outpatients with highly treatment-resistant, nonpsychotic major depressive episodes participating in a one-year open label study of vagus nerve stimulation to augment psychotropic medication treatment. Results: MADRS total scores averaged 31.9 (SD = 6.7) at baseline and 21.9 (SD = 11.0) at one year. QIDS-SR₁₆ total scores averaged 17.6 (SD = 3.6) at baseline and 12.5 (SD = 5.8) at one year. Based on one-year data (or exit if the patient did not complete one year), corresponding QIDS-SR₁₆ and MADRS total scores were presented for each possible QIDS-SR₁₆ and MADRS total score. A QIDS-SR₁₆ total score of 5 was comparable to a MADRS total score of 7 or 8 (7.5). Limitation: The degree to which these results generalize to less treatment-resistant samples is unknown. Conclusion: The conversion of QIDS-SR₁₆ and MADRS total scores provides a basis for clinicians who wish to use the QIDS-SR₁₆ to understand what MADRS total scores reported in clinical trials approximate QIDS-SR₁₆ total scores obtained with their patients.