title: Can demographic, clinical and treatment-related factors available at hormonal therapy initiation predict non-persistence in women with stage I-III breast cancer?
abstract: To investigate whether demographic, clinical and treatment-related risk factors known at treatment initiation can be used to reliably predict future hormonal therapy non-persistence in women with breast cancer, and to inform intervention development.
  
  
  
  Women with stage I-III breast cancer diagnosed 2000-2012 and prescribed hormonal therapy were identified from the National Cancer Registry Ireland (NCRI) and linked to pharmacy claims data from Ireland's Primary Care Reimbursement Services (PCRS). Non-persistence was defined as a treatment gap of ≥180 days within 5 years of initiation. Seventeen demographic, clinical and treatment-related risk factors, identified from a systematic review, were abstracted from the NCRI-PCRS dataset. Multivariate binomial models were used to estimate relative risks (RR) and risk differences (RD) for associations between risk factors and non-persistence. Calibration and discriminative performance of the models were assessed. The analysis was repeated for early non-persistence (<1 year of initiation).
  
  
  
  Within 5 years of treatment initiation 680 women (19.9%) were non-persistent. Women aged <50 years (adjusted RR 1.41, 95% CI 1.16-1.70) and those prescribed antidepressants (RR 1.22, 95% CI 1.04-1.45) had increased risk of non-persistence. Married women (RR 0.82 95% CI 0.71-0.94) and those with prior medication use (RR 0.62 95% CI 0.51-0.75) had reduced risk of non-persistence. The area under the receiver-operating characteristic (ROC) curve for non-persistence was 0.61. Findings were similar for early non-persistence.
  
  
  
  The risk prediction model did not discriminate well between women at higher and lower risk of non-persistence at treatment initiation. Future studies should consider other factors, such as psychological characteristics and experience of side-effects.
authors.affiliation: Division of Population Health Sciences, Royal College of Surgeons in Ireland, Beaux Lane House, Mercer Street Lower, Dublin 2, Ireland. caitrionacahir@rcsi.ie.
authors.forename: Caitriona
authors.initials: C
authors.lastname: Cahir
authors.affiliation: Trinity College Dublin, Ireland and Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Thomas I
authors.initials: TI
authors.lastname: Barron
authors.affiliation: Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Linda
authors.initials: L
authors.lastname: Sharp
authors.affiliation: Division of Population Health Sciences, Royal College of Surgeons in Ireland, Beaux Lane House, Mercer Street Lower, Dublin 2, Ireland.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Bennett
mesh_terms: D000367:Age Factors; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000523:psychology; D017024:Chemotherapy, Adjuvant; D003863:Depression; D005260:Female; D006801:Humans; D017533:Marital Status; D055118:Medication Adherence; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control*; D009367:Neoplasm Staging; D012042:Registries; D012307:Risk Factors
chemical_list: D018931:Antineoplastic Agents, Hormonal
keywords: Adherence; Breast cancer; Hormonal therapy; Medication taking behaviour; Persistence