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May 25, 2011 - Chinese validation of Pelvic Floor Distress Inventory and Pelvic Floor Impact Questionnaire. Symphorosa Shing Chee Chan & Rachel Yau Kar ...
Int Urogynecol J (2011) 22:1305–1312 DOI 10.1007/s00192-011-1450-z

ORIGINAL ARTICLE

Chinese validation of Pelvic Floor Distress Inventory and Pelvic Floor Impact Questionnaire Symphorosa Shing Chee Chan & Rachel Yau Kar Cheung & Alice Ka Wah Yiu & Jimmy Chak Man Li & Beatrice Pui Yee Lai & Kwong Wai Choy & Tony Kwok Hung Chung

Received: 8 December 2010 / Accepted: 3 May 2011 / Published online: 25 May 2011 # The International Urogynecological Association 2011

Abstract Introduction and hypothesis The purpose of this study was to investigate the reliability and validity of the Chinese version of Pelvic Floor Distress Inventory (PFDI) and Pelvic Floor Impact Questionnaire (PFIQ). Methods Women who presented for pelvic floor disorders completed the Chinese version of PFDI and PFIQ, SF-36, a 3day urinary and fecal diary. POP-Q assessment, urodynamic study, anal manometry, and ultrasound were performed where appropriate. Results Five hundred and ninety-seven women completed the study. The Cronbach’s alpha and test–retest reliability of PFDI and PFIQ was 0.92 and 0.98, and 0.77 and 0.79, respectively. Convergent validity was demonstrated with negative correlation of PFDI and PFIQ with SF-36; positive correlation of staging of prolapse, urinary or fecal incontinent episodes with the respective subscales of PFDI and PFIQ. Conclusions The Chinese version of PFDI and PFIQ are reliable and valid condition-specific health-related quality of life questionnaires for women with pelvic floor disorders.

Electronic supplementary material The online version of this article (doi:10.1007/s00192-011-1450-z) contains supplementary material, which is available to authorized users. S. S. C. Chan (*) : R. Y. K. Cheung : A. K. W. Yiu : B. P. Y. Lai : K. W. Choy : T. K. H. Chung Department of Obstetrics and Gynaecology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, 30–32 Ngan Shing Street, Shatin, New Territories, Hong Kong e-mail: [email protected] J. C. M. Li Department of Surgery, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong

Keywords Chinese . Pelvic floor disorders . PFDI . PFIQ . Quality of life . Urinary incontinence

Introduction Pelvic floor disorders include a wide variety of interrelated clinical conditions, namely pelvic organ prolapse (POP), urinary incontinence, voiding dysfunction, fecal incontinence, and defecatory dysfunction. POP was found in 11.4– 39.7% of women; urinary incontinence and or urinary symptoms occurred in 25–52%; and fecal incontinence is also reported by 1.4–22% of women [1–6]. It is also common for several pelvic floor disorders to co-exist in the same woman or to develop sequentially over time [7, 8]. Women suffering from pelvic floor disorders often suffered from urinary, bowel, or sexual symptoms; and in addition, they also have significant impairment of their quality of life (QOL) [7–9]. In Caucasian study, almost 50% of these women reported moderate or great distress, and 35% reported that the symptoms affected at least one physical, social, or sexual activity [9]. Chinese women who suffer from pelvic floor disorders should also have symptom distress and impairment on QOL. A comprehensive disease-specific symptoms and QOL instruments for pelvic floor disorders can assess the whole spectrum of interrelated symptoms associated with pelvic floor disorders, which is essential to better understand the relationship of various symptoms and to fully assess the impact of the disease on the women. Pelvic Floor Distress Inventory (PFDI) and Pelvic Floor Impact Questionnaire (PFIQ) are comprehensive instruments assessing the symptoms, severity of symptoms if present and impact of different types of pelvic floor disorders on a woman"s activities and well-being [10].

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Both PFDI and PFIQ are reliable, valid and conditionspecific symptoms and QOL instruments for women with pelvic floor disorders. Each scale of the PFDI and PFIQ has been proved to be internally consistent (αs: PFDI 0.82– 0.89; PFIQ 0.96–0.97) and reproducible (interclass correlations: PFDI 0.86–0.87; PFIQ 0.77–0.92). The aim of this study was to investigate the reliability and validity of disease-specific symptom and QOL questionnaires PFDI and PFIQ in Chinese women suffering from pelvic floor disorders. This would provide a standardized and reproducible assessment, and minimize clinician"s factor in varying the assessment. Moreover, validated questionnaire in this area would also serve as an objective instrument in assessing different therapy to pelvic floor disorders, which would be useful tools in the future.

Materials and methods Approval to use PFDI and PFIQ was obtained from the original author. Translation The PFDI and PFIQ were evaluated by two bilingual researchers (Cantonese Chinese speaking) in the fields of urogynecology independently and no item was regarded as inappropriate. They then performed the forward translation of the PFDI and PFIQ to literal Chinese independently. After that, they reviewed the two versions of translation and held a meeting for discussion on items of discrepancy, in order to produce one version. Back-translation was performed by another professional translator (bilingual in target language) in Chinese–English translation, and who did not have access to the original version of the questionnaire, after the iterative evaluation of forward translation process. The original and back-translated versions were compared for accuracy and comprehension by another two monolingual researchers. Finally, the back-translated version of both PFDI and PFIQ was sent to a monolingual English speaking expert (the original author) for review. Comments on the back-translated version were obtained and there was no major discrepancy. The Chinese version of the PFDI and PFIQ were finalized. Before the study phase, 36 women suffered from pelvic floor disorders were invited to perform the Chinese version of PFDI and PFIQ. They could understand and complete the questionnaires and they considered the questionnaires comprehensive on their pelvic floor disorders. Study phase From April 2009 to May 2010, all Chinese women attending the urogynecology clinic of the institute with pelvic floor

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disorders in the past 6 months before the consultation were invited to join the study. Exclusion criteria included less than 18 years, mental incapacity that would preclude completion of the questionnaire and those who refused to join. Written consent was obtained. They filled in the Chinese version PFDI and PFIQ and Short Form Health Survey (SF-36) before they attended the specialty clinic. The generic questionnaire SF-36 was used in this study to assess the validity of PFDI and PFIQ. It was designed to measure health-related QOL. It composes of eight domains and measures physical functioning, role limitation due to physical problems, role limitation due to emotional problems, social functioning, mental health, energy/vitality, pain, and general health perception. A Hong Kong Chinese version was available and has been validated for use [11]. After completing the questionnaires, the women were then assessed by the attending gynecologist, who was blinded to the information obtained from the questionnaires. Clinical data and socio-demographic data, including age, gravidity, parity, marital status, and menstrual status were asked. The attending gynecologist then examined them and determined the severity of the pelvic floor disorders. The staging of those suffered from POP was assessed by pelvic organ prolapse quantification (POP-Q) [12]. Both the women and the attending gynecologist were also asked independently to grade the overall severity of symptoms on a visual analog scale (VAS) with a higher score indicating higher severity of symptoms. Women were asked to keep a urinary diary and fecal diary for 3 days in the following week. The urinary and fecal diary helped in quantifying the severity of their urinary and bowel symptoms. A 3-day urinary diary has been shown to be reliable for documenting urinary frequency and number of incontinent episodes [13, 14]. The questionnaires were repeated 4 weeks later for the women recruited in the first 6 months of the study (n=270) to establish the test–retest reliability. All these women were not offered any treatment during this interval; data of those who had indicated stable symptoms before the retest were used for analysis in test–retest reliability. For the whole study population, women who had urinary symptoms were followed by uroflowmetry and cystometry testing; and those who had fecal incontinence were offered anal manometry and anal ultrasound scanning. The investigators who performed these investigations were blinded to the results obtained from the questionnaire. Statistics and sample size It has been recommended that the subject-to-item ratio of a given measurement scale should be 5:1 or above [15, 16]. There were 46 items in the PFDI and 93 items in the PFIQ. A sample size of 465 (93×5) was required to fulfill the

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above criteria and to assess the correlation of the scales with the SF-36 and objective measures of different pelvic floor disorders. According to a previous validation study of the PFDI and PFIQ[10], we estimate that the effect size of correlation to be moderate, i.e., r=0.30 [17]. Assuming an effect size of .30 and an alpha