title: Development of an endometriosis quality-of-life instrument: The Endometriosis Health Profile-30.
abstract: OBJECTIVE
  To describe a new disease-specific questionnaire with established measurement properties that addresses the dimensions of health-related quality 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 generate the items on the questionnaire. Stage 2 was an 87-item questionnaire administered in a postal survey to identify the most salient dimensions of health-related quality of life. In stage 3, the reliability and validity of the questionnaire were evaluated.
  
  
  RESULTS
  The final instrument contained a core questionnaire with 30 items and five scales: pain, control and powerlessness, emotional well-being, social support, and self-image. Six modular parts consisting of 23 questions were also developed and measured the areas of sexual intercourse, work, relationship with children, feelings about the medical profession, treatment, and infertility. All the scales achieved high internal reliability, with Cronbach's alpha coefficient ranging from 0.83 to 0.93 (core questionnaire) and 0.79 to 0.96 (modules). The intraclass correlation coefficients to evaluate the test-retest reliability were high (range 0.88-0.98, P <.001). Content validity was demonstrated as the questionnaire was developed from interviews of patients rather than existing literature and clinical scales. Construct 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).
  
  
  CONCLUSIONS
  The Endometriosis Health Profile-30 is a reliable, valid, patient-generated instrument to measure the health-related quality of life of women with endometriosis. Its application in various health care settings will provide new and valuable information on the effect of endometriosis on health-related quality of life from the patients' perspective.
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology and Health Services Research Unit, Division of Public Health and Primary Health Care, University of Oxford, United Kingdom. georgina.jones@obs-gyn.ox.ac.uk
authors.forename: G
authors.initials: G
authors.lastname: Jones
authors.forename: S
authors.initials: S
authors.lastname: Kennedy
authors.forename: A
authors.initials: A
authors.lastname: Barnard
authors.forename: J
authors.initials: J
authors.lastname: Wong
authors.forename: C
authors.initials: C
authors.lastname: Jenkinson
mesh_terms: D000293:Adolescent; D000328:Adult; D001294:Attitude to Health; D004715:Endometriosis / Q000523:psychology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010146:Pain; D011788:Quality of Life; D011795:Surveys and Questionnaires