title: Format and readability of an enhanced invitation letter did not affect participation rates in a cancer registry-based study: a randomized controlled trial.
abstract: OBJECTIVE
  To assess the effectiveness of an "enhanced" invitation letter in increasing participation in an Australian cancer registry-based study and assess the representativeness of the study sample.
  
  
  METHODS
  Eight hundred hematological cancer survivors, diagnosed within the last 3 years and aged 18-80 years at recruitment, were selected from one Australian state-based cancer registry. Half were randomly allocated to receive the standard invitation letter (control group). The remaining half received a modified invitation letter, incorporating content and design characteristics recommended to improve written communication (intervention group).
  
  
  RESULTS
  Of the 732 eligible survivors, 268 (37%) returned a completed survey. There was no difference in participation between the intervention (n = 131, 36%) and control groups (n = 137, 38%; P = 0.53). Participants were representative of the population for characteristics assessed, except for age group at diagnosis. Survivors 50 years or older at diagnosis had higher odds of returning a completed survey, 50-59 (odds ratio [OR]: 2.53; 95% confidence interval [CI]: 1.47, 4.35), 60-69 (OR: 2.69; 95% CI: 1.58-4.58), and 70-80 (OR: 1.90; 95% CI: 1.07-3.35), than survivors aged 15-39 years at diagnosis.
  
  
  CONCLUSIONS
  An enhanced invitation letter was not effective in increasing participation of hematological cancer survivors in an Australian cancer registry study. The study sample was moderately representative on variables assessed, with age group at diagnosis the only variable associated with participation. Research should evaluate strategies to increase participation in registry studies and focus on tailoring techniques to patient's age.
authors.affiliation: Priority Research Centre for Health Behaviour, Faculty of Health, University of Newcastle & Hunter Medical Research Institute, HMRI Building, Callaghan, New South Wales 2308, Australia. alix.hall@newcastle.edu.au
authors.forename: Alix E
authors.initials: AE
authors.lastname: Hall
authors.forename: Rob W
authors.initials: RW
authors.lastname: Sanson-Fisher
authors.forename: Marita C
authors.initials: MC
authors.lastname: Lynagh
authors.forename: Timothy
authors.initials: T
authors.lastname: Threlfall
authors.forename: Catherine A
authors.initials: CA
authors.lastname: D'Este
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia; D015709:Correspondence as Topic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000523:psychology / Q000628:therapy*; D018579:Patient Selection; D012042:Registries; D017741:Survivors; D055815:Young Adult