title: Development and validation of the Patient Assessment of Constipation Quality of Life questionnaire.
abstract: OBJECTIVE
  Chronic constipation is characterized by difficult, infrequent, or seemingly incomplete bowel movements. The Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaire was developed to address the need for a standardized, patient-reported outcomes measure to evaluate constipation over time.
  
  
  METHODS
  Items for the PAC-QOL were generated from the literature, clinical experts, and patients. Following principal components and multi-trait analyses, 28 items were retained forming four subscales (worries and concerns, physical discomfort, psychosocial discomfort, and satisfaction) and an overall scale. Validation studies were conducted in the United States, Europe, Canada, and Australia, to evaluate the internal consistency reliability (Cronbach's alpha), reproducibility (Intraclass Correlation Coefficients (ICCs)), validity (analysis of variance models), and responsiveness (effect size) of the PAC-QOL scales.
  
  
  RESULTS
  The PAC-QOL scales were internally consistent (Cronbach's alpha >0.80) and reproducible (ICCs >0.70, except for the satisfaction subscale ICC=0.66). PAC-QOL scale scores were significantly associated with abdominal pain (p<0.001) and constipation severity (p<0.05). Effect sizes in patients reporting improvements in constipation over a 6-week period were moderate to large, with subscale effect sizes ranging from 0.76 to 3.41 and the overall scale effect size=1.77. Similar findings were observed in validation studies conducted in Europe, Canada, and Australia.
  
  
  CONCLUSIONS
  The PAC-QOL is a brief but comprehensive assessment of the burden of constipation on patients' everyday functioning and well-being. Multinational studies demonstrate that the PAC-QOL is internally consistent, reproducible, valid, and responsive to improvements over time.
authors.affiliation: Mapi Values, Boston, MA, USA. patrick.marquis@mapivaluesusa.com
authors.forename: Patrick
authors.initials: P
authors.lastname: Marquis
authors.forename: Christine
authors.initials: C
authors.lastname: De La Loge
authors.forename: Dominique
authors.initials: D
authors.lastname: Dubois
authors.forename: Anne
authors.initials: A
authors.lastname: McDermott
authors.forename: Olivier
authors.initials: O
authors.lastname: Chassany
mesh_terms: D000328:Adult; D001294:Attitude to Health; D001315:Australia; D002170:Canada; D003248:Constipation / Q000523:psychology*; D003431:Cross-Cultural Comparison; D005060:Europe; D005260:Female; D017144:Focus Groups; D006801:Humans; D008297:Male; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D006113:United Kingdom; D014481:United States