title: Cost-effectiveness of Confirmatory Testing Before Treatment of Onychomycosis.
abstract: OBJECTIVE
  Onychomycosis is the most common disease of the nail in adults. International guidelines urge health care professionals to perform confirmatory diagnostic testing before initiating systemic therapy. This approach was determined to be cost-effective in studies from the late 1990s but has not been evaluated more recently. The effect of testing on the costs of efinaconazole, 10%, topical solution treatment is unknown.
  
  
  OBJECTIVE
  To evaluate the cost and potential harm associated with 3 approaches to onychomycosis evaluation before treatment with oral terbinafine or efinaconazole, 10%.
  
  
  METHODS
  A decision analysis that compared the costs of 3 onychomycosis management algorithms based on recently published data of test statistics, disease prevalence, and relevant costs: (1) empirical therapy without confirmatory testing, (2) pretreatment confirmatory testing with potassium hydroxide (KOH) stain followed by periodic acid-Schiff (PAS) evaluation if KOH testing is negative, and (3) pretreatment testing with PAS. There was no direct patient evaluation. Selection of included studies was based on outcome variables and the quality of study design. The study was conducted from April 1, 2014, to September 1, 2015.
  
  
  METHODS
  Primary outcomes included direct cost of onychomycosis testing and therapy and cost to avoid harm when treating patients with oral terbinafine.
  
  
  RESULTS
  At a disease prevalence of 75%, per-patient cost savings of empirical terbinafine therapy without confirmatory testing was $47 compared with the KOH screening model and $135 compared with PAS testing. The cost of testing necessary to prevent a single case of clinically relevant liver toxic effects related to terbinafine at a prevalence of 75% was between $18.2 million and $43.7 million for KOH screening and between $37.6 million and $90.2 million for PAS testing. At a prevalence of 75%, KOH screening and PAS testing before treatment with efinaconazole, 10%, saved $272 and $406 per patient per nail, respectively.
  
  
  CONCLUSIONS
  These results show that empirical treatment with terbinafine for patients with suspected onychomycosis is more cost-effective than confirmatory testing across all prevalence of disease, with minimal effect on patient safety. In contrast, confirmatory testing before treatment with efinaconazole, 10%, is associated with reduced costs. Blanket recommendations for confirmatory testing before systemic therapy should be reconsidered and replaced with recommendations tailored to specific therapies.
authors.affiliation: Department of Dermatology, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Anar
authors.initials: A
authors.lastname: Mikailov
authors.affiliation: Department of Dermatology, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Cohen
authors.affiliation: Department of Biostatistics and Bioinformatics, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana.
authors.forename: Cara
authors.initials: C
authors.lastname: Joyce
authors.affiliation: Department of Dermatology, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Arash
authors.initials: A
authors.lastname: Mostaghimi
mesh_terms: D000284:Administration, Oral; D000287:Administration, Topical; D000465:Algorithms; D017046:Cost Savings / Q000191:economics; D003362:Cost-Benefit Analysis / Q000706:statistics & numerical data*; D003661:Decision Support Techniques; D003663:Decision Trees; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D006878:Hydroxides / Q000191:economics; D009281:Naphthalenes / Q000009:adverse effects / Q000191:economics* / Q000627:therapeutic use*; D014009:Onychomycosis / Q000175:diagnosis / Q000188:drug therapy* / Q000191:economics*; D010503:Periodic Acid-Schiff Reaction; D017680:Potassium Compounds / Q000191:economics; D000067561:Potentially Inappropriate Medication List / Q000191:economics; D000077291:Terbinafine; D014230:Triazoles / Q000009:adverse effects / Q000191:economics* / Q000627:therapeutic use*
chemical_list: D006878:Hydroxides; D009281:Naphthalenes; D017680:Potassium Compounds; D014230:Triazoles; D000077291:Terbinafine; C431707:efinaconazole; C029943:potassium hydroxide