Effectiveness of voxelotor in individuals with sickle cell disease and a history of red blood cell transfusions: A non-interventional, retrospective cohort study using real-world data in the United States

Study type

• Study topic:
  Disease /health condition

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

Non-interventional study

• Non-interventional study design:
  Cohort

Study drug and medical condition

• Name of medicine:
  OXBRYTA
• Study drug International non-proprietary name (INN) or common name:
  VOXELOTOR
• Anatomical Therapeutic Chemical (ATC) code:
  (B06AX03) voxelotor

  voxelotor
• Medical condition to be studied:
  Sickle cell disease

Population studied

• Short description of the study population:
  The study population will include patients with SCD between the ages of 12 and 85 years of age who are enrolled in a health insurance plan continuously during the baseline period.
• Age groups:
  • Paediatric Population (< 18 years)

    • Adolescents (12 to < 18 years)
  • Adult and elderly population (≥18 years)

    • 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)
• Special population of interest:
  Other
• Special population of interest, other:
  Individuals with sickle cell disease and a history of red blood cell transfusions
• Estimated number of subjects:
  5000

Study design details

• Study design:
  This is a non-interventional, retrospective cohort study of individuals with SCD using a US real-world dataset composed of linked closed claims, proprietary voxelotor prescription claims, and laboratory data. ; Propensity score (PS) methods will be utilized to adjust for measured confounding covariat
• Main study objective:
  Compare the change in red blood cell (RBC) transfusions per patient per year (PPPY) from baseline (one year prior to index date) to follow-up (up to one year after index date).
• Setting:
  The study population will include patients with SCD between the ages of 12 and 85 years who are enrolled in a health insurance plan (commercial, Medicare, Medicaid) continuously during the 365 days prior to and including the index date (baseline). ; The index selection period is November 25, 2019 (date of FDA accelerated approval for voxelotor) through one year prior to the end of the study period. ; The exposed group will include patients with a new prescription claim for voxelotor (no prior use 365 days prior to index date), while the control group will include matched patients who do not have a prescription claim for voxelotor. Non-voxelotor controls will include those receiving no SCD modifying therapies as well as those receiving non-voxelotor SCD treatments to be reflective of clinical practice. ; Patients who are receiving chronic transfusion therapy for stroke prevention will be excluded from this analysis. ; Both the exposed and control groups may be treated with other SOC treatments such as HU.
• Data analysis plan:
  Detailed methodology for summary and statistical analyses of data collected in this study will be documented in the SAP, which will be dated, filed, and maintained by Pfizer. ; The SAP may modify the plans outlined in the protocol; any major modifications of primary endpoint definitions or their analyses would be reflected in a protocol amendment.