Correlation between the Incontinence Severity Index (ISI) and the quality of life dimensions of the King's Health Questionnaire (KHQ) in German-speaking urinary incontinent women.

BACKGROUND:The Incontinence Severity Index (ISI) is a patient questionnaire to ascertain severity of urinary incontinence (UI) via two items. The aim of this study was to translate the ISI into German, to compare it with the German-language King's Health Questionnaire (KHQ), an already validated German-language questionnaire within the scope of UI to measure condition-specific quality of life (QoL), and to gain more insights into association between symptom severity and QoL in German-speaking women affected. METHODS:A total of 161 urinary incontinent women completed the ISI and the KHQ. Mean scores of the KHQ domains were computed and separated into severity-groups ascertained by the ISI (slight, moderate, severe, and very severe). Differences between severity-groups were examined using Kruskal-Wallis and Mann-Whitney U test. Correlation between ISI and KHQ were computed using Spearman's correlation coefficient to investigate construct validity of the ISI as well as association between symptom severity and QoL. RESULTS:Overall, mean scores of the KHQ domains increased with increasing severity level. A consistent significant increase was found in role, physical, and social limitations (p < 0.05). Furthermore, the ISI showed moderate to strong correlations with related domains (convergent validity) and weak correlations with non-related domains of the KHQ (discriminant validity). CONCLUSIONS:Construct validity of the German-language ISI is acceptable. Therefore this study supports its use in German-speaking women but further studies have to be done to gain more comprehensive insights into its psychometric properties. Moreover, increasing symptom severity is associated with decreasing QoL, especially concerning role, physical, and social limitations. TRIAL REGISTRATION NUMBER:DRKS00018777.