Development of an endometriosis quality-of-life instrument: The endometriosis health profile-30

OBJECTIVE: To describe a new disease-specific questionnaire with establishe d measurement properties that addresses the dimensions of health-related qu ality of life considered important to women with endometriosis. METHODS: The Endometriosis Health Profile-30 was developed in three stages. Stage 1 included open-ended exploratory interviews with 25 women to genera te the items on the questionnaire. Stage 2 was an 87-item questionnaire adm inistered in a postal survey to identify the most salient dimensions of hea lth-related quality of life. In stage 3, the reliability and validity of th e questionnaire were evaluated. RESULTS: The final instrument contained a core questionnaire with 30 items and five scales: pain, control and powerlessness, emotional well-being, soc ial support, and self-image. Six modular parts consisting of 23 questions w ere also developed and measured the areas of sexual intercourse, work, rela tionship with children, feelings about the medical profession, treatment, a nd infertility. All the scales achieved high internal reliability, with Cro nbach's alpha coefficient ranging from 0.83 to 0.93 (core questionnaire) an d 0.79 to 0.96 (modules). The intraclass correlation coefficients to evalua te the test-retest reliability were high (range 0.88-0.98, P < .001). Conte nt validity was demonstrated as the questionnaire was developed from interv iews of patients rather than existing literature and clinical scales. Const ruct validity was assessed by correlating the Endometriosis Health Profile- 30 scales with the relevant Short Form-36 scales. High correlations for all comparisons were found (-0.41 to -0.73). CONCLUSION: The Endometriosis Health Profile-30 is a reliable, valid, patie nt-generated instrument to measure the health-related quality of life of wo men with endometriosis. Its application in various health care settings wil l provide new and valuable information on the effect of endometriosis on he alth-related quality of life from the patients' perspective. (C) 2001 by th e American College of Obstetricians and Gynecologists.