DARWIN EU® - Eye disorders in women with breast cancer treated with anastrozole, letrozole or tamoxifen

Study type

• Study topic:
  Human medicinal product
• Study type:
  Non-interventional study
• Scope of the study:
  Safety study (incl. comparative)
• Data collection methods:
  Secondary use of data

Non-interventional study

• Non-interventional study design:
  Cohort

Study drug and medical condition

• Study drug International non-proprietary name (INN) or common name:
  ANASTROZOLE
• Anatomical Therapeutic Chemical (ATC) code:
  (L02BG03) anastrozole

  anastrozole

  (L02BG04) letrozole

  letrozole

  (L02BA01) tamoxifen

  tamoxifen
• Medical condition to be studied:
  Eye disorder

Population studied

• Short description of the study population:
  The source population will include women aged 18 years and above with a primary diagnosis of breast cancer in the period between 01/01/2010 and 31/12/2022.
• Age groups:
  • Adults (18 to < 65 years)

    • Adults (18 to < 46 years)
    • Adults (46 to < 65 years)
  • Elderly (≥ 65 years)

    • Adults (65 to < 75 years)
    • Adults (75 to < 85 years)
    • Adults (85 years and over)

Study design details

• Study design:
  A new drugs user cohort study will be conducted to assess the incidence rates of eye disorders (primary objective), pre-specified patient-level characteristics (secondary objective 1) and median time to onset of the outcome (secondary objective 2).
• Main study objective:
  1. To calculate incidence rates and cumulative incidence of eye disorders, overall and stratified by eye disorder (Cataract, Degeneration of retina, Keratitis, Macular hole, Retinal artery occlusion, Retinal detachment, Retinal haemorrhage, Retinal tear, Retinal vascular disorder, Uveitis, Visual impairment, Vitreomacular traction syndrome and all visual system disorders combined), age category and type of therapy (anastrozole, letrozole or tamoxifen), among pre- and postmenopausal women with breast cancer (primary objective).; 2. To characterise postmenopausal women with breast cancer treated with anastrozole, letrozole or tamoxifen at the start of treatment in terms of demographics and potential risk factors for eye disorders (secondary objective). ; 3. To estimate the time from initiation of anastrozole, letrozole or tamoxifen to first eye disorder (overall) among postmenopausal women with breast cancer (secondary objective).;
• Setting:
  Routinely collected data from 5 databases in 5 European countries.
• Outcomes:
  The outcomes of interest were new events of selected eye disorders, their combination, and all visual system eye disorders: ; • Cataract, ; • Degeneration of retina ; • Keratitis ; • Macular hole ; • Retinal artery occlusion ; • Retinal detachment ; • Retinal haemorrhage ; • Retinal tear ; • Retinal vascular disorder ; • Uveitis ; • Visual impairment ; • Vitreomacular traction syndrome ; • All visual system disorders ; A preliminary list of concepts based on SNOMED codes is provided in the Annex II. The operational definition of the outcomes is presented in the Table 6.
• Summary results:
  CONCLUSION ; Using real-world data from five European countries, we identified heterogeneity in incidence rates of eye disorders across data sources and age groups, but when compared within a database, IRs in patients exposed to different drugs (anastrozole, letrozole and tamoxifen) were typically similar. There were no consistent or large differences in IRs of different eye disorders by the type of drug, particularly in postmenopausal women. However, some aspects such as absence of detailed clinical data (e.g. cancer stage) and lack of follow up across some databases should be considered when interpreting the result of this study.