title: Clinical diagnosis and outcomes for Troponin T 'positive' patients assessed by a high sensitivity compared with a 4th generation assay.
abstract: BACKGROUND
  High sensitivity troponin T (hsTnT) detects lower levels of troponin T with greater precision than the 4th generation (cTnT) assay. However, the clinical implications of this are uncertain.
  
  
  OBJECTIVE
  Primary: Describe the proportion of patients who test 'positive' with hsTnT but negative with cTnT. Secondary: Determine proportion in each group with an adverse event (representation, AMI or died) within 90 days of the index test.
  
  
  METHODS
  161 patients samples were tested with cTnT and hsTNT assays. McNemar's test was used to compare paired samples. Electronic medical records were reviewed, with discharge diagnosis and 90 day outcomes determined blind to hsTnT results. Patients were then classified as 'TnT negative' (hsTnT was <0.014 mcg/mL), 'new positive' (hsTnT was ≥ 0.014 mcg/mL and cTnT <0.03 mcg/mL) and 'TnT positive' (cTNT was ≥ 0.03 mcg/mL).
  
  
  RESULTS
  Positive results more than doubled with the hsTnT assay (50% vs 22%, P < 0.001). 81 patients were 'TnT negative', 44 were 'new positive' and 36 'cTnT positive'. The discharge diagnosis for 'new positives' was AMI in 4 (9%), other cardiac in 13 (30%) and non-cardiac in 27 (61%). At 90 days adverse events occurred in 30%, 54% and 50% of the groups respectively. There were no late cases of AMI or cardiovascular death in 'new positive' patients.
  
  
  CONCLUSIONS
  Many patients with diagnoses other than AMI will have hsTNT above the reference level. Indiscriminate testing with hsTnT might lead to more patients requiring serial troponin testing and/or invasive further tests, which will have process and resource implications for EDs and health services.
authors.affiliation: Adult Emergency Department, Auckland City Hospital, Auckland, New Zealand.
authors.forename: Sumeshni
authors.initials: S
authors.lastname: Jairam
authors.forename: Peter
authors.initials: P
authors.lastname: Jones
authors.forename: Luay
authors.initials: L
authors.lastname: Samaraie
authors.forename: Alexei
authors.initials: A
authors.lastname: Chataline
authors.forename: James
authors.initials: J
authors.lastname: Davidson
authors.forename: Ralph
authors.initials: R
authors.lastname: Stewart
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D004635:Emergency Medicine / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D020107:Troponin T