DEVELOPMENT A RELIABLE CHANGE INDEX FOR THE SELF-REPORTING QUESTIONNAIRE20: POTENTIAL USE IN CLINICAL AND RESEARCH SETTINGS

Abstract

Introduction: The use of scales and questionnaires for the assessment of psychiatric symptoms is of great importance for the clinical context as the search. One of the questionnaires commonly adopted in this field is the Self-Reported Questionnaire-20 (SRQ-20), a twenty items scale with binary score allocated to the evaluation of non-psychotic symptoms. We found no previously published reliable changing indexes for SRQ-20. Those are statistics used to compare the probability of change between pre-intervention and post-intervention scores over just the instrument of measurement error. Objectives: To establish reliable clinical change parameters for the SRQ-20. Methods: We evaluated 270 Brazilian adults aged 27.50 ± 9.23 years and high school 13:57 ± 3.40. Participants answered the SRQ-20. We calculate the internal consistency by the Kuder-Richardson method, test-retest reliability (in a subsample, n=40) by the Intraclass correlation coefficient, and computed a reliable change index. Results: The internal consistency of the scale in this population was 0.86, and test-retest reliability was 0.88. The reliable change index between two applications of the SRQ-20 is significant if occur ± 4 points change (p=0.10) or ± 5 points (p=0.05). Conclusion: The values ± 4 (p=0.10) and ± 5 (p=0.05) can be used in clinical, and research contexts to evaluate reliable clinical change in SRQ-20 scores.