title: Self-administered versus interview-based questionnaires among patients with intermittent claudication: Do they give different results? A cross-sectional study.
abstract: OBJECTIVE
  Many clinical investigations use generic and/or specific questionnaires to obtain information about participants and patients. There is disagreement about whether the administration method can affect the results. The aim here was to determine whether, among patients with intermittent claudication (IC), there are differences in the Walking Impairment Questionnaire (WIQ) and European Quality of Life-5 Dimension (EQ-5D) scores with regard to: 1) the questionnaire administration method (self-administration versus face-to-face interview); and 2) the type of interviewer (vascular surgeon, VS, versus general practitioner, GP).
  
  
  METHODS
  Cross-sectional observational multicenter epidemiological study carried out within the Spanish National Health Service.
  
  
  METHODS
  1,641 evaluable patients with IC firstly completed the WIQ and EQ-5D questionnaires and then were interviewed by their doctor on the same day. Pearson correlations and Chi-square tests were used.
  
  
  RESULTS
  There was a strong correlation (r > 0.800; P < 0.001) between the two methods of administering the WIQ and EQ-5D questionnaires, and between the VS and GP groups. Likewise, there was a high level of concordance (P > 0.05) between the different dimensions of the WIQ-distance and EQ-5D (self-administration versus face-to-face) in the VS and GP groups.
  
  
  CONCLUSIONS
  There was no difference between the different methods of administering the WIQ and EQ-5D questionnaires, among the patients with IC. Similarly, the two types of interviewers (VS or GP) were equally valid. Therefore, it seems unnecessary to expend effort to administer these questionnaires by interview, in studies on IC.
authors.affiliation: Angiology and Vascular Surgery Department, Hospital Universitario de Salamanca, Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Lozano
authors.affiliation: Centro de Salud Villablanca, Madrid, Spain.
authors.forename: José María
authors.initials: JM
authors.lastname: Lobos
authors.affiliation: Angiology and Vascular Surgery Department, Hospital Universitario de Getafe, Madrid, Spain.
authors.forename: José Ramón
authors.initials: JR
authors.lastname: March
authors.affiliation: Centro de Salud Jesús H. Gómez Tornero, Abarán, Murcia, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Carrasco
authors.affiliation: Angiology and Vascular Surgery Department, Hospital Universitario de Valladolid, Valladolid, Spain.
authors.forename: Marcello Barbosa
authors.initials: MB
authors.lastname: Barros
authors.affiliation: Hematology Department, Hospital Universitario de Salamanca, Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain.
authors.forename: José Ramón
authors.initials: JR
authors.lastname: González-Porras
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D059026:Diagnostic Self Evaluation; D005260:Female; D006801:Humans; D007383:Intermittent Claudication / Q000175:diagnosis / Q000453:epidemiology*; D007407:Interviews as Topic / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012647:Self-Assessment; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires / Q000592:standards*; D016138:Walking