title: A valid and reliable measure of constipation-related quality of life.
abstract: OBJECTIVE
  Few existing measures assess constipation-specific quality of life. This study sought to develop a valid and reliable quality-of-life measure for constipation.
  
  
  METHODS
  First, we created a preliminary instrument that assessed quality-of-life domains affected by constipation: body image, eating, mood, and relationships with others. We conducted focus groups both with patients with constipation seeking treatment and the health care providers who treat them. Next, a 59-item questionnaire was given to 240 subjects with constipation (83% female) and 103 healthy volunteers (63% female). Test-retest reliability and discriminant, convergent, and divergent validity were assessed.
  
  
  RESULTS
  Exploratory factor analysis revealed four domains: Social Impairment (five items), Distress (six items), Eating Habits (three items), and Bathroom Attitudes (four items). Internal consistency and test-retest reliability for all subscales was high (Cronbach's alpha = 0.89; intraclass correlation coefficient = 0.87). All domains discriminated well between subjects with constipation and healthy volunteers (P < 0.001). Convergent validity was excellent: all subscales correlated highly with the Irritable Bowel Syndrome Quality of Life Scale total score (P < 0.001) and the Medical Outcomes Study Short Form-36 physical component and mental component summary scores (P < 0.001). Scores from our Constipation-Related Quality of Life measure were not significantly correlated with the Social Desirability Scale, demonstrating divergent validity.
  
  
  CONCLUSIONS
  Our findings support the reliability and validity of the Constipation-Related Quality of Life measure. Future validation of the Constipation-Related Quality of Life measure for assessing changes in quality of life in response to treatments for constipation is needed.
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, California 94115, USA.
authors.forename: Jennifer Y
authors.initials: JY
authors.lastname: Wang
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Hart
authors.forename: Janet
authors.initials: J
authors.lastname: Lee
authors.forename: Julia R
authors.initials: JR
authors.lastname: Berian
authors.forename: G Lindsay
authors.initials: GL
authors.lastname: McCrea
authors.forename: Madhulika G
authors.initials: MG
authors.lastname: Varma
mesh_terms: D000328:Adult; D003248:Constipation / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*