Table 3.

Reference intervals of PRO-C3 in patients with NAFLD or NASH.

	N	Lower limit (ng/ml) [90% CI]	Upper limit (ng/ml) [90% CI]	Median (ng/ml) [90% CI]	Skewness
F0/F1	56	6.1 [6.1–6.4]	15.0 [13.7–16.2]	9.5 [8.6–10.2]	0.019
F2	59	6.1 [6.1–6.5]	25.4 [21.2–29.5]	11.5 [10.7–13.1]	0.63∗
F3	60	8.0 [7.1–9.1]	27.4 [24.1–30.7]	14.5 [13.5–15.8]	-0.49
F4	40	6.1 [6.1–7.3]	54.2 [39.1–69.8]	16.3 [15.0–20.5]	0.54
NASH	134	6.3 [6.1–6.9]	31.2 [27.8–35.0]	13.8 [12.9–14.9]	0.47∗
Fibrotic NASH	119	6.5 [6.1–7.2]	34.4 [30.0–38.9]	14.6 [13.7–15.9]	0.56∗

Reference intervals were estimated by the robust method according to the recommended approach (CLSI C28-A3). PRO-C3 levels below the lower limit of quantification were assigned the lowest acceptable concentration. NASH was defined as lobular inflammation ≥1, ballooning ≥1, and NAS ≥4. Fibrotic NASH was defined as NASH with fibrosis stage ≥2. Outliers were detected on log-transformed data using test Tukey’s criterion, and excluded. Skewness estimates are based on the log-transformed data. Statistical significance: ∗p <0.05. CLSI, Clinical and Laboratory Standards Institute; NAS, non-alcoholic fatty liver disease activity score; NASH, non-alcoholic steatohepatitis.