Translation and psychometric evaluation of the simplified Chinese-version Endometriosis Health Profile-30.

STUDY QUESTION: What are the psychometric properties in mainland China of the 30-item Endometriosis Health Profile (EHP-30) translated into simplified Chinese?

SUMMARY ANSWER: The simplified Chinese version of the EHP-30 is a valid, reliable and acceptable tool for the measurement of the health-related quality of life (HRQoL) of women with endometriosis in the context of mainland China.

WHAT IS KNOWN ALREADY: Endometriosis can critically affect women's HRQoL. The EHP-30 is currently the most reliable instrument to measure the HRQoL in women with endometriosis.

STUDY DESIGN, SIZE, DURATION: This cross-sectional study was conducted in a tertiary referral university hospital from February 2012 to August 2012 in Beijing, P. R. China.

PARTICIPANTS/MATERIALS, SETTING, METHODS: The translation and cultural adaptation of the EHP-30 was performed according to accepted guidelines. The study included 336 women with endometriosis. Psychometric evaluation included factor analysis, convergent validity, measurement of internal consistency, item-total correlations and data completeness, descriptive statistics, and the determination of floor and ceiling effects.

MAIN RESULTS AND THE ROLE OF CHANCE: Factor analysis confirmed the validity of the five-factor structure of the EHP-30 core questionnaire, which explained 79.51% of the total variance. The correlations of related subscale scores between EHP-30 and Short Form-36 were all significant. Cronbach's α for internal consistency across each scale ranged 0.89-0.97 for the core questionnaire and 0.80-0.96 for the modular questionnaire. No <97.67% of data completeness was achieved. Floor effects were observed in three scales: self-image (19.64%), children (26.67%) and medical profession (15.19%). No ceiling effects were found. The control and powerlessness scale had the highest median score (54.17) in the core questionnaire, whereas the infertility module (median = 56.25) had the highest score in the modular section.

LIMITATIONS, REASONS FOR CAUTION: The study was conducted in a referral centre for the treatment of endometriosis, thereby leading to overrepresentation of severe symptoms of endometriosis. Furthermore, the test-retest reliability and responsiveness of the questionnaire were not evaluated in this study.

WIDER IMPLICATIONS OF THE FINDINGS: Our study addresses the urgent need for a valid and reliable instrument to measure the HRQoL of female patients with endometriosis in mainland China.

STUDY FUNDING/COMPETING INTEREST(S): This work was supported by grants to J. Leng from the Key Project for Clinical Faculty Foundation, Ministry of Health, China (2010). None of the authors has any conflict of interest to declare.