title: A questionnaire to identify patellofemoral pain in the community: an exploration of measurement properties.
abstract: Community-based studies of patellofemoral pain (PFP) need a questionnaire tool that discriminates between those with and those without the condition. To overcome these issues, we have designed a self-report questionnaire which aims to identify people with PFP in the community.
  
  
  
  
  
  
  
  comparative study and cross-sectional study.
  
  
  
  comparative study: PFP patients, soft-tissue injury patients and adults without knee problems. Cross-sectional study: adults attending a science festival.
  
  
  
  comparative study participants completed the questionnaire at baseline and two weeks later. Cross-sectional study participants completed the questionnaire once. The optimal scoring system and threshold was explored using receiver operating characteristic curves, test-retest reliability using Cohen's kappa and measurement error using Bland-Altman plots and standard error of measurement. Known-group validity was explored by comparing PFP prevalence between genders and age groups.
  
  
  
  Eighty-four participants were recruited to the comparative study. The receiver operating characteristic curves suggested limiting the questionnaire to the clinical features and knee pain map sections (AUC 0.97 95 % CI 0.94 to 1.00). This combination had high sensitivity and specificity (over 90 %). Measurement error was less than the mean difference between the groups. Test-retest reliability estimates suggest good agreement (N = 51, k = 0.74, 95 % CI 0.52-0.91). The cross-sectional study (N = 110) showed expected differences between genders and age groups but these were not statistically significant.
  
  
  
  A shortened version of the questionnaire, based on clinical features and a knee pain map, has good measurement properties. Further work is needed to validate the questionnaire in community samples.
authors.affiliation: College of Clinical and Biomedical Sciences, University of Central Lancashire, Preston, PR1 2HE, UK. MPDey@uclan.ac.uk.
authors.forename: Paola
authors.initials: P
authors.lastname: Dey
authors.affiliation: Department of Health Professions, Manchester Metropolitan University, Manchester, M15 6GX, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Callaghan
authors.affiliation: College of Clinical and Biomedical Sciences, University of Central Lancashire, Preston, PR1 2HE, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Cook
authors.affiliation: 5 Boroughs Partnership NHS Foundation Trust, St Helens Hospital, Marshalls Cross Road, St Helens, WA9 3DA, UK.
authors.forename: Ruth
authors.initials: R
authors.lastname: Sephton
authors.affiliation: College of Health and Wellbeing, University of Central Lancashire, Preston, PR1 2HE, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Sutton
authors.affiliation: 5 Boroughs Partnership NHS Foundation Trust, St Helens Hospital, Marshalls Cross Road, St Helens, WA9 3DA, UK.
authors.forename: Elaine
authors.initials: E
authors.lastname: Hough
authors.affiliation: 5 Boroughs Partnership NHS Foundation Trust, St Helens Hospital, Marshalls Cross Road, St Helens, WA9 3DA, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: James
authors.affiliation: Stepping Hill Hospital, Stockport Foundation NHS Trust, Poplar Grove, Hazel Grove, Stockport, Cheshire, SK2 7JE, UK.
authors.forename: Rukhtam
authors.initials: R
authors.lastname: Saqib
authors.affiliation: Department of Health Professions, Manchester Metropolitan University, Manchester, M15 6GX, UK.
authors.forename: James
authors.initials: J
authors.lastname: Selfe
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D046788:Patellofemoral Pain Syndrome / Q000175:diagnosis*; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Diagnosis; Differential; Patellofemoral pain; Reliability; Sensitivity and specificity; Validation studies