title: Bayesian analyses demonstrate tissue blood volume is not decreased during acute sickle cell pain episodes: A preliminary study.
abstract: BACKGROUND
  Pain is the most common complication of Sickle Cell Disease (SCD). Tissue oximetry properties in SCD during steady state and acute pain are not well described.
  
  
  METHODS
  This was a cross sectional study of tissue oximetry properties in individuals with SCD during steady state, acute pain and healthy controls without SCD. A novel tissue oximetry device was used to better account for tissue pigmentation interference. We hypothesized that during acute SCD pain, blood volume to painful areas would be at least 10% less than steady state. Bayesian analyses of the data (with flat piors) were planned a priori because of the small projected sample size.
  
  
  RESULTS
  The sample included 14 individuals (4 during crisis, 5 steady state, and 5 controls). In individuals with SCD, blood volume to the lower back was higher during crisis (0.18% of tissue volume vs. 0.14% ). Bayesian analyses yielded a 3% probability that our hypothesis (that blood volume would decrease by 10% ) was correct.
  
  
  CONCLUSIONS
  During acute SCD pain, blood volume to painful areas is not decreased. Bayesian analyses were useful for interpretation of small sample data and may have utility in early phase trials for rare diseases.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Perry
authors.affiliation: Division of Hematology and Medical Oncology, Mount Sinai Hospital, New York, NY, USA.
authors.forename: Jena
authors.initials: J
authors.lastname: Simon
authors.affiliation: Laboratory of Investigative Dermatology, The Rockefeller University, New York, NY, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gareau
authors.affiliation: Department of Emergency Medicine, Division of Hematology and Medical Oncology, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Glassberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000755:Anemia, Sickle Cell / Q000097:blood*; D001499:Bayes Theorem; D001810:Blood Volume / Q000502:physiology*; D003430:Cross-Sectional Studies; D006801:Humans; D008875:Middle Aged; D010146:Pain / Q000209:etiology*; D055815:Young Adult
keywords: Sickle cell disease; pain crisis; tissue oximetry