title: Aspirin for primary prevention of vascular events in women: individualized prediction of treatment effects.
abstract: AIMS To identify women who benefit from aspirin 100 mg on alternate days for primary prevention of vascular events by using treatment effect prediction based on individual patient characteristics. METHODS AND RESULTS Randomized controlled trial data from the Women's Health Study were used to predict treatment effects for individual women in terms of absolute risk reduction for major cardiovascular events (i.e. myocardial infarction, stroke, or cardiovascular death). Predictions were based on existing risk scores, i.e. Framingham (FRS), and Reynolds (RRS), and on a newly developed prediction model. The net benefit of different aspirin treatment-strategies was compared: (i) treat no one, (ii) treat everyone, (iii) treatment according to the current guidelines (i.e. selective treatment of women >65 years of age or having >10% FRS), and (iv) prediction-based treatment (i.e. selective treatment of patients whose predicted treatment effect exceeds a given decision threshold). The predicted reduction in 10-year absolute risk for major cardiovascular events was <1% in 97.8% of 27 939 study subjects when based on the refitted FRS, in 97.0% when based on the refitted RRS, and in 90.0% when based on the newly developed model. Of the treatment strategies considered, only prediction-based treatment using the newly developed model and selective treatment of women >65 years of age yielded more net benefit than treating no one, provided that the 10-year number-willing-to-treat (NWT) to prevent one cardiovascular event was above 50. CONCLUSION Aspirin was ineffective or even harmful in the majority of patients. Age was positively related to treatment effect, whereas current smoking and baseline risk for cardiovascular events were not. When the NWT is 50 or lower, the aspirin treatment strategy that is associated with optimal net benefit in primary prevention of vascular events in women is to treat none.
authors.affiliation: Department of Vascular Medicine, University Medical Center Utrecht, The Netherlands.
authors.forename: Johannes A N
authors.initials: JA
authors.lastname: Dorresteijn
authors.forename: Frank L J
authors.initials: FL
authors.lastname: Visseren
authors.forename: Paul M
authors.initials: PM
authors.lastname: Ridker
authors.forename: Nina P
authors.initials: NP
authors.lastname: Paynter
authors.forename: Annemarie M J
authors.initials: AM
authors.lastname: Wassink
authors.forename: Julie E
authors.initials: JE
authors.lastname: Buring
authors.forename: Yolanda
authors.initials: Y
authors.lastname: van der Graaf
authors.forename: Nancy R
authors.initials: NR
authors.lastname: Cook
mesh_terms: D000368:Aged; D001241:Aspirin / Q000008:administration & dosage* / Q000009:adverse effects; D002318:Cardiovascular Diseases / Q000401:mortality / Q000517:prevention & control*; D004334:Drug Administration Schedule; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality / Q000517:prevention & control; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects; D011322:Primary Prevention; D012307:Risk Factors; D020521:Stroke / Q000401:mortality / Q000517:prevention & control; D016896:Treatment Outcome
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin
references.citation: JAMA. 2006 Jan 18;295(3):306-13
references.pmid: 16418466
references.citation: Circulation. 2011 Feb 22;123(7):768-78
references.pmid: 21343593
references.citation: Med Decis Making. 2006 Nov-Dec;26(6):565-74
references.pmid: 17099194
references.citation: Circulation. 2002 Jul 16;106(3):388-91
references.pmid: 12119259
references.citation: Future Cardiol. 2010 Mar;6(2):141-6
references.pmid: 20230255
references.citation: BMJ. 2011 Oct 03;343:d5888
references.pmid: 21968126
references.citation: N Engl J Med. 2005 Mar 31;352(13):1293-304
references.pmid: 15753114
references.citation: Trials. 2007 Jun 05;8:14
references.pmid: 17550609
references.citation: Lancet. 2009 May 30;373(9678):1849-60
references.pmid: 19482214
references.citation: JAMA. 2007 Feb 14;297(6):611-9
references.pmid: 17299196
references.citation: N Engl J Med. 1989 Jul 20;321(3):129-35
references.pmid: 2664509
references.citation: J Womens Health Gend Based Med. 2000 Jan-Feb;9(1):19-27
references.pmid: 10718501
references.citation: JAMA. 2001 May 16;285(19):2486-97
references.pmid: 11368702
references.citation: J Am Coll Cardiol. 2011 Mar 22;57(12):1404-23
references.pmid: 21388771
references.citation: J Clin Epidemiol. 2006 Oct;59(10):1087-91
references.pmid: 16980149
references.citation: Ann Intern Med. 2009 Mar 17;150(6):396-404
references.pmid: 19293072