title: Platelet-reactivity tests identify patients at risk of secondary cardiovascular events: a systematic review and meta-analysis.
abstract: BACKGROUND
  Antiplatelet therapy is the standard treatment for the prevention of cardiovascular events (CVEs). High on-treatment platelet reactivity (HPR) is a risk factor for secondary CVEs in patients prescribed aspirin and/or clopidogrel. The present review and meta-analysis was aimed at assessing the ability of individual platelet-function tests to reliably identify patients at risk of developing secondary CVEs.
  
  
  RESULTS
  A systematic literature search was conducted to identify studies on platelet-reactivity measurements and CVEs. The main inclusion criteria were: (i) prospective study design; (ii) study medication, including aspirin and/or clopidogrel; and (iii) a platelet-function test being performed at baseline, before follow-up started. Of 3882 identified studies, 102 (2.6%; reporting on 44 098 patients) were included in the meta-analysis. With regard to high on-aspirin platelet reactivity (HAPR), 22 different tests were discussed in 55 studies (22 441 patients). Pooled analysis showed that HAPR was diagnosed in 22.2% of patients, and was associated with an increased CVE risk (relative risk [RR] 2.09; 95% confidence interval [CI] 1.77-2.47). Eleven HAPR tests independently showed a significantly increased CVE risk in patients with HAPR as compared with those with normal on-aspirin platelet reactivity. As regards high on-clopidogrel platelet reactivity (HCPR), 59 studies (34 776 patients) discussed 15 different tests, and reported that HCPR was present in 40.4% of patients and was associated with an increased CVE risk (RR 2.80; 95% CI 2.40-3.27). Ten tests showed a significantly increased CVE risk.
  
  
  CONCLUSIONS
  Patients with HPR are suboptimally protected against future cardiovascular complications. Furthermore, not all of the numerous platelet tests proved to be able to identify patients at increased cardiovascular risk.
authors.affiliation: Department of Vascular Surgery, UMC Utrecht, Utrecht, the Netherlands.
authors.forename: P P
authors.initials: PP
authors.lastname: Wisman
authors.forename: M
authors.initials: M
authors.lastname: Roest
authors.forename: F W
authors.initials: FW
authors.lastname: Asselbergs
authors.forename: P G
authors.initials: PG
authors.lastname: de Groot
authors.forename: F L
authors.initials: FL
authors.lastname: Moll
authors.forename: Y
authors.initials: Y
authors.lastname: van der Graaf
authors.forename: G J
authors.initials: GJ
authors.lastname: de Borst
mesh_terms: D001241:Aspirin / Q000008:administration & dosage / Q000009:adverse effects; D001792:Blood Platelets / Q000166:cytology*; D002318:Cardiovascular Diseases / Q000097:blood* / Q000175:diagnosis*; D000077144:Clopidogrel; D003324:Coronary Artery Disease / Q000150:complications / Q000188:drug therapy; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000009:adverse effects; D010979:Platelet Function Tests / Q000379:methods*; D011446:Prospective Studies; D012307:Risk Factors; D013988:Ticlopidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin
keywords: aspirin; clopidogrel; meta-analysis; platelets; thrombosis