title: Informing disinvestment with limited evidence: cobalamin deficiency in the fatigued.
abstract: OBJECTIVE
  Health technology reassessment and disinvestment can be difficult due to uncertainties regarding available evidence. Pathology testing to investigate cobalamin (vitamin B12) deficiency is a strong case in point. We conducted a 3-month economic evaluation of five strategies for diagnosing and treating cobalamin deficiency in adult patients hypothetically presenting with new unexplained fatigue in the primary care setting. The first consultation per patient was considered. Screening tests other than serum cobalamin were not included.
  
  
  METHODS
  A cost-effectiveness analysis was undertaken using a decision tree to represent the diagnostic / treatment pathways, with relevant cost and utility scores assigned to different stages in the evaluation process. Input parameter values were estimated from published evidence, supplemented by expert opinion, with sensitivity analysis undertaken to represent parameter uncertainty.
  
  
  RESULTS
  Ordering serum vitamin B12 to assess cobalamin deficiency among patients with unexplained fatigue was not cost-effective in any patient population, irrespective of pretest prevalence of this deficiency. For patients with a pretest prevalence above 1 percent, treating all with oral vitamin B12 supplements without testing was most cost-effective, whereas watchful waiting with symptoms monitoring was most cost-effective for patients with lower pretest prevalence probabilities.
  
  
  CONCLUSIONS
  Substantial evidence gaps exist for parameter estimation: questionable cobalamin deficiency levels in the fatigued; debatable treatment methods; unknown natural history of the condition. Despite this, we reveal a robust path for disinvestment decision making in the face of a paradox between the evidence required to inform disinvestment compared with its paucity in informing initial funding decisions.
authors.affiliation: School of Allied Health,Faculty of Health Sciences,Australian Catholic University.
authors.forename: George
authors.initials: G
authors.lastname: Mnatzaganian
authors.affiliation: Discipline of Public Health,School of Population Health,University of Adelaide.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Karnon
authors.affiliation: Discipline of Public Health,School of Population Health,University of Adelaide.
authors.forename: John R
authors.initials: JR
authors.lastname: Moss
authors.affiliation: Menzies Centre for Health Policy,Sydney School of Public Health,Sydney Medical School,The University of Sydney.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Elshaug
authors.affiliation: ClinPath Laboratories,Adelaide.
authors.forename: Michael
authors.initials: M
authors.lastname: Metz
authors.affiliation: Discipline of General Practice,School of Population Health,University of Adelaide.
authors.forename: Oliver R
authors.initials: OR
authors.lastname: Frank
authors.affiliation: Discipline of Public Health,School of Population Health,University of Adelaide;School of Health Sciences,Faculty of Health Arts and Design,Swinburne University of Technologyjhiller@swin.edu.au.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Hiller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001774:Blood Chemical Analysis; D003362:Cost-Benefit Analysis; D019587:Dietary Supplements; D005221:Fatigue / Q000097:blood* / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017059:Models, Econometric; D019057:Quality-Adjusted Life Years; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000150:complications* / Q000175:diagnosis* / Q000188:drug therapy; D055815:Young Adult
chemical_list: D014805:Vitamin B 12
keywords: Cost-effectiveness analysis; Disinvestment; Fatigue; Pathology testing; Vitamin B12 deficiency