Table 2.
PRO-C3 reference range in healthy volunteers.
| N | Lower limit (ng/ml) [90% CI] | Upper limit (ng/ml) [90% CI] | Median (ng/ml) | Skewness | |
|---|---|---|---|---|---|
| Total healthy | 269 | 6.1 [6.1–6.1] | 14.7 [14.0–15.3] | 8.9 [8.5–9.2] | 0.36∗ |
| Sex | |||||
| Male | 103 | 6.1 [6.1–6.1] | 14.9 [13.6–16.1] | 8.7 [8.4–9.1] | 0.45 |
| Female | 166 | 6.1 [6.1–6.1] | 14.6 [13.9–15.5] | 9.1 [8.5–9.6] | 0.3 |
| Age, years | |||||
| ≤22 | 13 | 6.1 [6.1–6.5] | 20.0 [15.0–25.3] | 10.0 [8.5–13.1] | 0.35 |
| 22–29 | 58 | 6.1 [6.1–6.1] | 14.6 [13.3–16.0] | 9.1 [8.4–9.7] | 0.22 |
| 30–39 | 64 | 6.1 [6.1–6.1] | 13.6 [12.5–14.8] | 8.5 [7.9–9.5] | 0.37 |
| 40–49 | 44 | 6.1 [6.1–6.1] | 14.3 [12.6–16.0] | 8.4 [8.0–9.3] | 0.5 |
| 50–59 | 46 | 6.1 [6.1–6.1] | 15.1 [13.2–16.8] | 8.6 [7.9–9.6] | 0.41 |
| 60–69 | 26 | 6.1 [6.1–6.9] | 16.9 [14.7–19.1] | 10.1 [8.6–11.1] | -0.22 |
| 70+ | 17 | 6.1 [6.1–6.1] | 16.0 [13.2–19.3] | 9.1 [7.3–10.5] | 0.27 |
| BMI stage | |||||
| Normal | 69 | 6.1 [6.1–6.2] | 14.8 [13.6–16.0] | 9.4 [8.5–9.8] | 0.22 |
| Overweight | 101 | 6.1 [6.1–6.1] | 14.1 [13.1–15.2] | 8.5 [8.1–8.9] | 0.39 |
| Obese | 96 | 6.1 [6.1–6.1 | 14.6 [13.6–15.5] | 9.0 [8.4–9.3] | 0.15 |
| Ethnicity | |||||
| Asian | 27 | 6.1 [6.1–6.6] | 14.5 [12.8–16.5] | 9.3 [8.2–10.4] | 0.32 |
| Black | 51 | 6.1 [6.1–6.1] | 16.1 [14.5–17.9] | 9.3 [8.4–10.6] | 0.25 |
| Hispanic | 22 | 6.1 [6.1–6.9] | 15.1 [13.2–16.8] | 9.6 [8.4–10.4] | -0.34 |
| White | 167 | 6.1 [6.1–6.1] | 14.1 [13.3–14.9] | 8.6 [8.1–9.0] | 0.36 |
Stratified according to sex, age strata, obesity, and ethnicity. BMI status was defined as healthy (BMI 18.5–24.9), overweight (BMI 25.0–29.5), and obese (BMI ≥30). Except for the age groups ‘<22’ and ‘70+’ in which the number of patients was too low, the lower and upper limits with 90% CIs were estimated using the robust method (CLSI C28-A3). For the age group ‘≤20’ and ‘>70’ the lower and upper limits were estimated using the robust method, but the 90% CIs for the lower and upper limits were estimated based on the assumption that the data had a log-normal distribution. PRO-C3 levels below the lower limit of quantification were assigned the lowest acceptable concentration. Outliers were detected on log-transformed data using test Tukey’s criterion, and excluded. Skewness estimates are based on the log-transformed data. Significance level: ∗p <0.05.