title: Using a simulation model to assess risk of false negative point-of-care urinary human chorionic gonadotropin device results due to high-dose hook interference.
abstract: BACKGROUND
  It is unclear if the point-of-care (POC) Clinitest hCG device is subject to high-dose hook interference from physiological concentrations of intact human chorionic gonadotropin (hCG), β-core fragment of hCG (hCGβcf), and hCG free β-subunit (hCGβ) found in urine during pregnancy. We used a simulation model to address this question and related our findings to our institution's pregnant population in order to assess risk for potential false-negative hCG results.
  
  
  METHODS
  The expected distribution of days relative to ovulation during routine POC hCG testing was estimated from 182 patients. Clinitest-Clinitek Status hCG device susceptibility to high-dose hook interference from hCG variants and potential risk of false-negative results as it relates to this population were evaluated by testing increasing concentrations of hCG, hCGβcf, hCGβ as well as urine simulating physiological hCG, hCGβcf and hCGβ concentrations expected during early pregnancy (≤44 days post-ovulation).
  
  
  RESULTS
  The Clinitest-Clinitek Status hCG device exhibited high-dose hook interference from hCGβcf alone, but not from hCG, hCGβ, or simulated physiological urinary concentrations of combined hCG, hCGβcf and hCGβ expected during early pregnancy. The majority of our patient population had urinary hCG testing conducted during early pregnancy.
  
  
  CONCLUSIONS
  The Clinitest-Clinitek Status hCG device is unlikely to exhibit false-negative urinary hCG results due to high-dose hook interference for women in early healthy pregnancy, although additional studies are necessary to determine potential risk in other patient populations. Visual interpretation of POC urinary hCG device results is an important failure mode to consider in risk analyses for erroneous urinary hCG device results.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Denise
authors.initials: D
authors.lastname: Milhorn
authors.affiliation: Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA. Electronic address: nkorpist@unch.unc.edu.
authors.forename: Nichole
authors.initials: N
authors.lastname: Korpi-Steiner
mesh_terms: D006063:Chorionic Gonadotropin / Q000652:urine*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000652:urine; D003198:Computer Simulation; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008962:Models, Theoretical; D010060:Ovulation; D010446:Peptide Fragments / Q000652:urine; D019095:Point-of-Care Systems; D011247:Pregnancy; D011933:Reagent Kits, Diagnostic; D018570:Risk Assessment
chemical_list: D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D010446:Peptide Fragments; D011933:Reagent Kits, Diagnostic; C063554:urinary gonadotropin fragment
keywords: Hook effect; Point-of-care; Variant hook effect; hCG; hCGβcf