Added Value of Fecal Calprotectin to Support the Diagnosis of Spondyloarthropathies

Article Figures & Data

Table 1.

Diagnostic performance of different fecal calprotectin assays to support the diagnosis of SpA.

	Quantum Blue Calprotectin		LIAISON Calprotectin	QUANTA Lite Calprotectin Extended Range
AUC (95% CI)	0.658 (0.556–0.750)		0.684 (0.583–0.774), p = 0.2964^*	0.661 (0.559–0.754), p = 0.9056^*
Median (95% CI) in SpA (n = 52)	59.0 µg/g (39.9–82.0)		25.4 µg/g (15.8–38.7)	24.6 µg/g (15.2–32.6)
Median (95% CI) in non-SpA (n = 47)	32 µg/g (15.0–45.4), p = 0.0056^§		11.5 µg/g (7.9–16.6), p = 0.0017^§	13.0 µg/g (10.9–15.6) p = 0.0057^§
Manufacturer’s cutoff	50 µg/g	200 µg/g	50 µg/g	50 µg/g	120 µg/g
Sensitivity for SpA (95% CI)	56% (41–70)	6% (1–16)	29% (17–43)	15% (7–28)	0% (0–7)
Specificity for SpA (95% CI)	68% (53–81)	98% (89–100)	94% (83–99), p < 0.0001^**	96% (86–100), p < 0.0001^**	98% (89–100)
Cutoff at 98% specificity for SpA	157 µg/g		62 µg/g	60 µg/g
Sensitivity for SpA (95% CI)	13% (6–26)		21% (11–35)	8% (2–19)
Likelihood ratio for SpA (95% CI)	6.3 (0.8–49.5)		9.9 (1.3–74.1)	3.6 (0.4–31.2)
OR for SpA (95% CI)	7.2 (0.8–60.5), p = 0.1308^§§		12.3 (1.5–99.8), p = 0.018^§§	3.8 (0.4–35.6), p = 0.2372^§§

↵* Evaluation performed versus AUC Quantum Blue Calprotectin using the method of DeLong, et al, in MEDCALC software (version 17.1).
↵§ Mann-Whitney U test (independent samples).
↵** McNemar test (paired proportions) versus Quantum Blue Calprotectin.
↵§§ OR calculated using the method of Altman, et al, in MEDCALC: if the associated p value is < 0.05 it can be concluded that the OR is significantly different from 1 and that the odds in 1 group are significantly higher than in the other. SpA: spondyloarthropathies; AUC: area under the curve.

Table 2.

Performance of different tests to support the diagnosis of SpA.

	R, n = 80	R + HLA-B27, n = 67	R + HLA-B27 + FC, n = 67	FC, n = 99	HLA-B27 + FC, n = 81	R + FC, n = 80
Sensitivity (95% CI)	36% (24–50)	67% (52–79)	74% (59–85), p = 0.2482^*	21% (11–35)	71% (57–82)	55% (41–68) p = 0.0026^**
Specificity (95% CI)	94% (80–98)	84% (65–94)	84% (65–94)	98% (89–100)	78% (62–88)	88% (73–95)
LR (95% CI)	6.0 (1.5–24.1)	4.2 (1.7–10.5)	4.6 (1.8–11.5)	9.9 (1.3–74.1)	3.2 (1.7–6.1)	4.6 (1.8–11.8)
OR (95% CI)	8.8 (1.9–41.3)	10.5 (3.0–36.5)	14.8 (4.1–52.8)	12.3 (1.5–99.8)	8.6 (3.1–23.8)	9.0 (2.7–29.6)

↵* McNemar test (paired proportions) versus R + HLA-B27.
↵** McNemar test (paired proportions) versus R. With n = no. patients for which the test(s) was/were performed. SpA: spondyloarthritis; R: radiology (radiograph and/or MRI); FC: fecal calprotectin analysis with LIAISON Calprotectin performed at cutoff of 62 µg/g, corresponding to a 98% specificity for SpA; LR: likelihood ratio; MRI: magnetic resonance imaging.