title: Survival analysis and its associated factors of Beta thalassemia major in hamadan province.
abstract: BACKGROUND
  There currently is a lack of knowledge about the long-term survival of patients with beta thalassemia (BT), particularly in regions with low incidence of the disease. The aim of the present study was to determine the survival rate of the patients with BT major and the factors associated with the survival time.
  
  
  METHODS
  This retrospective cohort study was performed in Hamadan province, located in the west of Iran. The study included patients that referred to the provincial hospitals during 16 year period from 1997 to 2013. The follow up of each subject was calculated from the date of birth to the date of death. Demographic and clinical data were extracted from patients' medical records using a checklist. Statistical analysis included the Kaplan-Meier method to analyze survivals, log-rank to compare curves between groups, and Cox regression for multivariate prognostic analysis.
  
  
  RESULTS
  A total of 133 patients with BT major were enrolled, 54.9% of whom were male and 66.2% were urban. The 10-, 20- and 30-year survival rate for all patients were 98.3%, 88.4% and 80.5%, respectively. Based on hazard ratio (HR), we found that accompanied diseases (P=0.01), blood type (P=0.03) and residency status (P=0.01) were significant predictors for the survival time of patients.
  
  
  CONCLUSIONS
  The survival rate of BT patients has improved. Future researches such as prospective designs are required for the estimation of survival rate and to find other prognostic factors, which have reliable sources of data.
authors.affiliation: Center for Disease Control and Prevention, Deputy of Health Services, Hamadan University of Medical Sciences, Hamadan, Iran;
authors.forename: Reza
authors.initials: R
authors.lastname: Zamani
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Science, Tehran, Iran;
authors.forename: Salman
authors.initials: S
authors.lastname: Khazaei
authors.affiliation: Department of Epidemiology, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Shahab
authors.initials: S
authors.lastname: Rezaeian
keywords: Iran; Kaplan-Meier estimate; Survival; Thalassemia