title: One-step homogeneous C-reactive protein assay for saliva.
abstract: BACKGROUND
  Cardiovascular disease is the leading cause of death in the world. Human C-reactive protein (CRP) has been used in the risk assessment of coronary events. Human saliva mirrors the body's health and well-being and is non-invasive, easy to collect and ideal for third world countries as well as for large patient screening. The aim was to establish a saliva CRP reference range and to demonstrate the clinical utility of salivary CRP levels in assessing the coronary events in a primary health care setting.
  
  
  METHODS
  We have used a homogeneous bead based assay to detect CRP levels in human saliva. We have developed a rapid 15 min (vs 90 min), sequential, one-step assay to detect CRP in saliva. Saliva was collected from healthy volunteers (n=55, ages 20-70 years) as well as from cardiac patients (n=28, ages 43-86 years).
  
  
  RESULTS
  The assay incubation time was optimised from 90 min to 15 min and generated a positive correlation (n=29, range 10-2189 pg/mL, r2=0.94; Passing Bablok slope 0.885, Intercept 0, p>0.10), meaning we could decrease the incubation time and produce equivalent results with confidence. The mean CRP level in the saliva of healthy human volunteers was 285 pg/mL and in cardiac patients was 1680 pg/mL (p<0.01). Analysis of CRP concentrations in paired serum and saliva samples from cardiac patients gave a positive correlation (r2=0.84, p<0.001) and the salivary CRP concentration capable of distinguishing healthy from diseased patients.
  
  
  CONCLUSIONS
  The results suggest that this minimally invasive, rapid and sensitive assay will be useful in large patient screening studies for risk assessment of coronary events.
authors.affiliation: The School of Chemical Engineering, The University of Queensland, Brisbane, Australia. c.punyadeera@uq.edu.au
authors.forename: Chamindie
authors.initials: C
authors.lastname: Punyadeera
authors.forename: Goce
authors.initials: G
authors.lastname: Dimeski
authors.forename: Karam
authors.initials: K
authors.lastname: Kostner
authors.forename: Peter
authors.initials: P
authors.lastname: Beyerlein
authors.forename: Justin
authors.initials: J
authors.lastname: Cooper-White
mesh_terms: D000293:Adolescent; D000328:Adult; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000032:analysis*; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism*; D006801:Humans; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012463:Saliva / Q000737:chemistry*; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D002097:C-Reactive Protein