title: An analysis of first-time blood donors return behaviour using regression models.
abstract: OBJECTIVE
  Blood products have a vital role in saving many patients' lives. The aim of this study was to analyse blood donor return behaviour.
  
  
  METHODS
  Using a cross-sectional follow-up design of 5-year duration, 864 first-time donors who had donated blood were selected using a systematic sampling. The behaviours of donors via three response variables, return to donation, frequency of return to donation and the time interval between donations, were analysed based on logistic regression, negative binomial regression and Cox's shared frailty model for recurrent events respectively.
  
  
  RESULTS
  Successful return to donation rated at 49·1% and the deferral rate was 13·3%. There was a significant reverse relationship between the frequency of return to donation and the time interval between donations. Sex, body weight and job had an effect on return to donation; weight and frequency of donation during the first year had a direct effect on the total frequency of donations. Age, weight and job had a significant effect on the time intervals between donations.
  
  
  CONCLUSIONS
  Aging decreases the chances of return to donation and increases the time interval between donations. Body weight affects the three response variables, i.e. the higher the weight, the more the chances of return to donation and the shorter the time interval between donations. There is a positive correlation between the frequency of donations in the first year and the total number of return to donations. Also, the shorter the time interval between donations is, the higher the frequency of donations.
authors.affiliation: Biostatistics and Epidemiology Department, Clinical Biochemistry Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Kheiri
authors.affiliation: Research Center of Iranian Blood Transfusion Organization, Shahrekord, Iran.
authors.forename: Z
authors.initials: Z
authors.lastname: Alibeigi
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001519:Behavior; D001782:Blood Donors / Q000523:psychology* / Q000706:statistics & numerical data; D001789:Blood Group Antigens; D001835:Body Weight; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007492:Iran; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D016016:Proportional Hazards Models; D012737:Sex Factors; D012959:Socioeconomic Factors; D013997:Time Factors; D055815:Young Adult
chemical_list: D001789:Blood Group Antigens
keywords: first-time donor; recurrent event; regression model; return rate