Table 3.

Comparison of overall test performance among those with both CRP and ESR performed simultaneously, N = 43 820^a

Disease outcomeb	n	CRP AUCc (95% CI)	ESR AUC (95% CI)	P-value for CRP versus ESR	CRP and ESR AUC (95% CI)	P-value for combined versus better single test
Any relevant disease	3977	0.682 (0.672 to 0.690)	0.665 (0.656 to 0.674)	<0.001	0.688 (0.678 to 0.697)	<0.001
Infections	1565	0.617 (0.601 to 0.632)	0.589 (0.574 to 0.603)	<0.001	0.619 (0.604 to 0.634)	0.018
Autoimmune conditions	1663	0.710 (0.697 to 0.724)	0.708 (0.695 to 0.721)	0.680	0.724 (0.710 to 0.737)	<0.001
Cancer	882	0.774 (0.759 to 0.788)	0.766 (0.752 to 0.781)	0.017	0.777 (0.763 to 0.791)	0.006
Polymyalgia rheumatica/giant cell arteritis	476	0.882 (0.880 to 0.900)	0.872 (0.860 to 0.890)	0.099	0.887 (0.874 to 0.900)	0.110
Rheumatoid arthritis	557	0.691 (0.670 to 0.712)	0.690 (0.669 to 0.711)	0.890	0.700 (0.679 to 0.721)	0.007
Seronegative arthritis	151	0.700 (0.653 to 0.746)	0.686 (0.638 to 0.734)	0.510	0.706 (0.659 to 0.753)	0.540
Inflammatory bowel disease	223	0.698 (0.660 to 0.737)	0.691 (0.653 to 0.730)	0.450	0.701 (0.662 to 0.740)	0.510

^aOnly 9494 (total amount in 1st column) out of the total 43 820 had a relevant disease outcome. The analysis of test performance uses those with and without relevant disease hence the total n = 43 820 is correct here.

^bWhere disease subtypes were examined, diseases other than the specified condition reported were classified as non-diseased.

^cAUC = area under the receiver operator curve, where AUC = 0.5 is equivalent to no diagnostic utility and AUC = 1 is perfect diagnostic accuracy. AUC was calculated using logistic regression modelling with test result(s) on a log scale and age and sex as additional explanatory variables. CRP = C-reactive protein. ESR = erythrocyte sedimentation rate.