title: Estimating the effect of an intensive surveillance program on stage of breast carcinoma at diagnosis: a propensity score analysis.
abstract: BACKGROUND
  The authors used propensity score adjustment to investigate the impact of intensive screening on stage of breast carcinoma at diagnosis in women who were at elevated risk for breast carcinoma.
  
  
  METHODS
  The authors compared 58 women participating in a surveillance program at the Columbia Presbyterian Medical Center of New York Presbyterian Hospital who developed breast carcinoma with 3022 nonparticipating breast carcinoma patients. A propensity score was constructed for each woman by using important background covariates, and multivariable regression modeling was used to estimate the association of program membership with disease stage after adjusting for the propensity score.
  
  
  RESULTS
  Before propensity score adjustment, nine baseline covariates significantly differed between the two groups (number of pregnancies, number of births, age at first delivery, race, how the tumor was discovered, history of prior breast disease, breast carcinoma in mother, breast carcinoma in maternal aunt, and breast carcinoma in sister), and there was a significant difference in stage at diagnosis. After adjustment, no significant differences remained. Program participants were more likely to have lower stage tumors at diagnosis than nonparticipants, but this association did not reach statistical significance (odds ratio, 1.52; 95% confidence interval, 0.94--2.46).
  
  
  CONCLUSIONS
  Propensity score methods can remove bias in treatment comparisons in observational studies. An intensive surveillance program at a major cancer center may have had some effect on improving stage at diagnosis, but this effect was not statistically significant.
authors.affiliation: Division of Biostatistics, Mailman School of Public Health, Columbia University, New York, New York 10032, USA. nm133@columbia.edu
authors.forename: N
authors.initials: N
authors.lastname: Mitra
authors.forename: F R
authors.initials: FR
authors.lastname: Schnabel
authors.forename: A I
authors.initials: AI
authors.lastname: Neugut
authors.forename: D F
authors.initials: DF
authors.lastname: Heitjan
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis*; D019937:Diagnostic Techniques and Procedures; D005260:Female; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D019370:Observation / Q000379:methods; D012044:Regression Analysis