Determination of the reliability of the stuttering severity instrument-fourth edition specific adults who stutter

Document Type : Original Articles


1 MSc, Department of Speech Therapy, School of Rehabilitation Sciences, Isfahan University of Medical sciences, Isfahan, Iran

2 Lecture, Academic Member, Department of Speech Therapy, School of Rehabilitation Sciences, Isfahan University of Medical Sciences, Isfahan, Iran

3 PhD in Biostatistics, Department of Biostatistics and Epidemiology, School of Health, Isfahan University Medical Sciences, Isfahan, Iran

4 MSc in Psychometric, Isfahan Insurance Organization, Isfahan, Iran

5 PhD, Department of Psychology and Language Sciences, University College London, England



Introduction: Stuttering Severity Instrument-Fourth Edition (named hereafter SSI-4) is one of the most wildly recognized and reliable measures of stuttering severities to date. This instrument has been used for describing some aspects of stuttering and also for measuring treatment outcomes. Considering the importance of outcome measurement in evidence- based practice and the paucity of reliable instruments to make such estimates in Iran, it was decided to determine the reliability of SSI-4 through this study.Materials and Methods: After being translated in to Persian according to IQOLA protocol, the reliability of instrument was evaluated in a sample of 35 adults who stutter. 5 experienced raters scored each subject's stuttering severity using SSI-4.Results: Inter- and intra-rater reliability was determined using Cronbach's alpha coefficient, Intra-class correlation coefficient (ICC), and one way ANOVA. ICC values ranged from 0.93 to 0.98 for inter-rater reliability and from 0.85 to 0.98 for intra-rater reliability. One way ANOVA with repeated measures did not provide any evidence of mean difference between the severity scores obtained from weekly assessments.Conclusion: Regarding to the high reliability of SSI-4 reported in this study, it can be concluded that the Persian version of SSI-4 is an appropriate instrument for evaluating stuttering severity in adults who stutter. However, the point that has to be made here is that SSI-4 address only one aspect of stuttering, namely its severity, and cannot cover all complicacies of the disorder.Keywords: Stuttering severity score, Inter and intra- judge agreement, Evidence -based practice, Reproducibility of results