title: The (mis)classification of chemo-fog--methodological inconsistencies in the investigation of cognitive impairment after chemotherapy.
abstract: BACKGROUND
  A growing number of studies report cognitive impairment after chemotherapy; indeed the phenomenon of chemo-fog is now almost universally accepted. We are concerned however that there is little if any consistency in the way in which patients are classified as showing cognitive impairment or not. We aim to demonstrate that different methods of analysis produce markedly different results, making the true extent of impairment unclear.
  
  
  METHODS
  We analysed data from 92 breast cancer patients 4 weeks post-chemotherapy and from 42 healthy controls using 7 different methods, each taken from a different research paper in the area of cognitive impairment post-chemotherapy.
  
  
  RESULTS
  The extent of impairment was dependent on the method of analysis. Impairment ranged from 12 to 68.5% in the chemotherapy group and from 4.8 to 64.3% in the healthy control group.
  
  
  CONCLUSIONS
  This brief report highlights the contrasting degrees of cognitive impairment calculated by using legitimate statistical methods and demonstrates the need for a collaborative effort to standardise our methods that we might better understand the phenomenon of chemo-fog.
authors.affiliation: Cancer Research UK Psychosocial Oncology Group, Brighton and Sussex Medical School University of Sussex, Falmer East Sussex, UK. v.m.shilling@sussex.ac.uk
authors.forename: Val
authors.initials: V
authors.lastname: Shilling
authors.forename: Valerie
authors.initials: V
authors.lastname: Jenkins
authors.forename: Ivonne Solis
authors.initials: IS
authors.lastname: Trapala
mesh_terms: D000970:Antineoplastic Agents / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000188:drug therapy; D003072:Cognition Disorders / Q000139:chemically induced* / Q000145:classification*; D005260:Female; D006801:Humans; D009483:Neuropsychological Tests
chemical_list: D000970:Antineoplastic Agents