Platelet function testing to predict hyporesponsiveness to clopidogrel in patients with chest pain seen in the emergency department

Figures & data

Table 1 Patient characteristics stratified by clopidogrel hyporesponsiveness, with PRU = 230 as the cutoff

	PRU < 230	PRU ≥ 230	P value
Gender
Male	187 (60.1%)	96 (43.2%)	<0.001
Female	124 (39.9%)	126 (56.8%)
Age
Mean (SD)	63.6 (12.3)	65.4 (13.2)	0.110
Race
Caucasian	244 (78.5%)	142 (64.0%)	<0.001
African American	66 (21.2%)	75 (33.8%)
Asian	1 (0.3%)	2 (0.9%)
Other	0 (0.0%)	3 (1.4%)
Type 1 diabetes
Yes	6 (1.9%)	5 (2.3%)	1.000
No	304 (97.7%)	217 (97.7%)
Unknown	1 (0.3%)	0 (0.0%)
Type 2 diabetes
Yes	76 (24.4%)	90 (40.5%)	<0.001
No	234 (75.2%)	131 (59.0%)
Unknown	1 (0.3%)	1 (0.5%)
Hypertension
Yes	266 (85.5%)	194 (87.4%)	0.795
No	42 (13.5%)	28 (12.6%)
Unknown	3 (1.0%)	0 (0.0%)
Smoking
Yes	136 (43.7%)	83 (37.4%)	0.153
No	173 (55.6%)	138 (62.2%)
Unknown	2 (0.6%)	1 (0.5%)
Chronic renal failure
Yes	57 (18.3%)	48 (21.6%)	0.378
No	253 (81.4%)	174 (78.4%)
Unknown	1 (0.3%)	0 (0.0%)
Obesity
Yes	133 (42.8%)	98 (44.1%)	0.790
No	177 (56.9%)	123 (55.4%)
Unknown	1 (0.3%)	1 (0.5%)

Notes: Fisher’s Exact test (or Student’s t-test for age) was used to test for dependence between hyporesponsiveness and each patient characteristic. There was a statistically significant bivariate association with gender, race, and type 2 diabetes, with the higher risk of hyporesponsiveness associated with female gender, African American race, and having type 2 diabetes. There is a marginally significant (P = 0.110) association with increasing age.

Abbreviations: PRU, P2Y12 reaction units; SD, standard deviation.

Figure 1 Scatter plot of percent P2Y12 inhibition versus PRU.

Notes: Points to the right of the vertical red line are patients for whom PRU was ≥230, while points below the horizontal red line are for patients in whom percent P2Y12 inhibition was <30. Points in the lower right quadrant (n = 208, 39.2%) are judged clopidogrel-hyposensitive by both criteria, while points in the upper left quadrant (n = 231, 43.5%) are judged clopidogrel-responsive by both criteria. Points in the upper right and lower left quadrants (n = 92, 17.3%) have discordant judgments based on the two criteria. For comparison, a dotted gray line is drawn at the alternative PRU = 208 cutoff.
Abbreviation: PRU, P2Y12 reaction units.

Table 2 Multivariable logistic regression model of hyporesponsiveness to clopidogrel (PRU ≥ 230)

Variable	Estimate	SE	Z value	P value	Adjusted OR
					Estimate	95% CI
Intercept	−1.827	0.618	−2.957	0.0031*
Gender (female)	0.595	0.191	3.113	0.0019*	1.813	1.248	2.641
Age (decades)	0.155	0.082	1.899	0.0575	1.167	0.996	1.372
Race (African American)	0.772	0.215	3.589	0.0003*	2.165	1.423	3.312
Type 1 diabetes	−0.109	0.692	−0.158	0.8747	0.897	0.212	3.432
Type 2 diabetes	0.746	0.206	3.618	2.97E-04*	2.109	1.410	3.166
Hypertension	−0.299	0.287	−1.041	0.2980	0.742	0.424	1.309
Smoking	−0.038	0.202	−0.190	0.8496	0.962	0.648	1.431
Chronic renal failure	0.110	0.233	0.475	0.6349	1.117	0.706	1.760
Obesity	0.015	0.194	0.076	0.9396	1.015	0.693	1.485

Notes: Parameter estimates, standard errors, P values (H₀: β = 0 versus nonzero alternative), and adjusted OR for each of nine predictors and 95% CI.

* P > 0.05.

Abbreviations: CI, confidence interval; OR, odds ratio; SE, standard error; PRU, P2Y12 reaction units.