healthmedicinet

Research article

Ilia Makedonov¹, Sumei Gu², Lawrence F Paszat^123* and on behalf of the investigators of the Ontario Cancer Screening Research Network

• *
  Corresponding author: Lawrence F Paszat [email protected]

Author Affiliations

Abstract (provisional)

Background The Ontario Breast Screening Program (OBSP) is a population-based breast
screening programme, not requiring physician referral. OBSP invites women by mail
to book their next screens. However, women who do not participate in the OBSP, may
be referred by physicians to non-OBSP mammography facilities, which do not remind
women to book their next screen. Methods We identified women without breast cancer
prior to June 30, 2011, having bilateral mammography (M) during a baseline period
at age 50 – 69 at OBSP or non-OBSP facilities, and during a re-exposure period, at
the same facility type. We used a case-control design to study the association of
facility type and having M during an outcome period. Cases were women failing to receive
the outcome M. Controls were matched by age, census tract, and socioeconomic status.
Exposure was baseline facility type. Covariates were comorbidity, residential mobility,
and primary care physician (PCP) characteristics. Conditional logistic regression
analysis was performed. Results Cases were less likely to have been screened at OBSP
facilities. Failure to receive the outcome M was associated with having moved after
re-exposure M (OR?=?1.61, 95% confidence interval (CI) 1.52, 1.71), having a male
PCP (OR?=?1.05, 95% CI 1.02, 1.05), or a higher Charlson score (OR?=?1.06 per unit
increase, 95% CI 1.03, 1.09). Having re-exposure M at an OBSP facility (OR?=?0.18,
95% CI 0.18, 0.19)., having a Canadian trained PCP (OR?=?0.83, 95% CI 0. 8, 0.87),
and having a PCP one year after the re-exposure M (OR?=?0.81, 95% CI 0.68, 0.97) were
protective against failure to receive the outcome M. Conclusions The OBSP, not requiring
physician referral, and inviting women by mail to book their next screen, is associated
with a lower probability of failure to reattend for subsequent screening than screening
by PCP referral to non-OBSP facilities.