Cultural adaptation of a quality-of-life measure for urinary incontinence.

Objectives: To translate and validate a urinary incontinence-specific measure of quality of life (I-QOL) in French, Spanish, Swedish, and German and provide translations only into seven other languages and variants of these languages.
Methods: Quality of life and linguistic experts prepared two forward translations from American English to their native languages and helped to harmonize these translations at a meeting. In the four European countries, the adapted versions of the I-QOL were administered to 259 women with stress, urge, and mixed incontinence. Principal component analyses were used to confirm the proposed measurement model suggested by patient interviews. Psychometric testing was conducted using standardized procedures.
Results: Translation procedures resulted in a change in the original instrument's Likert response scale from 4 to 5 points. Principal component analyses confirmed three patient-derived subscales and higher-order factor analysis confirmed a total summary score. In all countries, the internal consistency (alpha) and reproducibility (ICC) were high (alpha ranged between 0.87 and 0.93); (ICC ranged between 0.92 and 0.95). In all countries, I-QOL scores were significantly worse (p < 0.001) as perceived severity of incontinence, use of services, and number of incontinent episodes increased.
Conclusions: The I-QOL has been adapted successfully into eleven languages and six variants of these languages. The cross-sectional psychometric properties of the US version were confirmed in four European countries. The I-QOL fills the need for a valid, international quality-of-life instrument for incorporation in clinical trials covering patients with varying types and severity of urinary incontinence.