Table 5:
Sensitivity, specificity, and positive and negative predictive values for FGF-21 and conventional serum biomarkers for mitochondrial diseases*
| Sensitivity | Specificity | Positive predictlvevalue | Negative predictlvevalue | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FGF-21 | Lac | Pyru | L:P† | CK | FGF-21 | Lac | Pyru | L:P† | CK | FGF-21 | Lac | Pyru | L:P† | CK | FGF-21 | Lac | Pyru | L:P† | CK | |
| Adult muscle-manifesting mitochondrial disorders (MELAS, PEO, and MNGIE; n=29) | 89.7 (72.7–97.8) | 40.0 (21.161–3) | 63.6 (30.8–891) | 9.0 (0.2–41.3) | 31.8 (13.9–549) | 91.7 (84.8–96.1) | 92.7 (83.9–97.6) | 87.2 (74.2–95.2) | 100.0 (92.5–100.0) | 73.7 (62.3–83.1) | 74.3 (56.7–87.5) | 66.7 (38.4–88.2) | 53.9 (25.1–80.8) | 100.0 (2.5–100.0) | 25.9 (11.1–46.3) | 97.1 (91.6–99.4) | 81.0 (70.6–89.0) | 91.1 (78.8–97.5) | 82.5 (70.1–91.3) | 78.9 (67.6–87.7) |
| Adult mito-chondrial disorders with nervous system involvement (MIRAS; n=12) | 41.7 (15.2–72.3) | 9.1 (0.2–41.3) | 77.8 (40.0–97.2) | 0(0–7.6) | 8.3 (0.2–38.5) | 91.7 (84.8–96.1) | 92.8 (83.9–97.6) | 87.2 (74.3–95.2) | 100.0 (66.4–100.0) | 73.7 (62.3–83.1) | 35.7 (12.8–64.9) | 16.7 (0.4–64.1) | 53.9 (25.1–80.8) | NA‡ | 4.8 (0.1–23.8) | 93.4 (86.9–97.3) | 86.5 (76.6–93.3) | 95.4 (84.2–99.4) | 83.9 (717–92.4) | 83.6 (72.5–91.5) |
| Child muscle-manifesting mitochondrial disorders (n=23) | 95.7 (78.1–99.9) | 90.5 (69.6–98.8) | 83.3 (51.6–97.9) | 75.0 (42.8–94.5) | 70.0 (34.8–93.3) | 91.7 (84.8–96.1) | 92.8 (83.9–97.6) | 83.3 (51.6–97.9) | 100.0 (92.5–100.0) | 73.7 (62.3–83.1) | 71.0 (52.0–85.8) | 79.2 (57.9–92.9) | 62.5 (35.4–84.8) | 100.0 (66.4–100.0) | 25.9 (11.1–46.3) | 99.0 (94.6–100.0) | 87.0 (89.5–99.6) | 95.4 (84.2–99.4) | 94.0 (83.5–98.8) | 94.9 (85.9–98.9) |
| Adult and child muscle-manifesting mitochondrial disorders (n=52) | 92.3 (81.5–97.9) | 63.0 (47.6–76.8) | 73.9 (51.6–89.8) | 43.5 (23.2–65.5) | 43.8 (26.4–62.3) | 91.7 (84.8–96.1) | 92.8 (83.9–97.6) | 87.2 (74.3–95.2) | 100.0 (92.5–100.0) | 73.7 (62.3–83.1) | 84.2 (72.1–92.5) | 85.3 (68.9–95.1) | 73.9 (51.6–89.8) | 100.0 (69.2–100.0) | 41.2 (24.7–59.3) | 96.1 (90.4–94.9) | 79.0 (68.5–87.3) | 87.2 (74.3–95.2) | 78.3 (65.8–87.9) | 75.7 (64.3–84.9) |
| All mito-chondrial disorders (n=64) | 82.8 (71.3–91.1) | 52.6 (39.0–66.0) | 75.0 (56.6–88.5) | 31.3 (16.1–50.0) | 34.1 (20.5–49.9) | 91.7 (84.8–96.1) | 92.8 (83.9–97.6) | 87.2 (74.3–95.2) | 100.0 (92.5–100.0) | 73.7 (62.3–83.1) | 85.5 (74.2–93.1) | 85.7 (69.7–95.2) | 80.8 (61.4–92.3) | 100.0 (69.2–100.0) | 42.9 (26.3–60.7) | 90.0 (82.8–94.9) | 70.3 (59.8–79.5) | 83.7 (70.3–92.6) | 68.1 (55.8–78.8) | 65.9 (54.8–75.8) |
Values are percentages (95% CI). Lac=lactate. Pyru=pyruvate. L:P=lactate-to-pyruvate ratio. CK=creatine kinase. MELAS=mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. PEO=progressive external ophthalmoplegia. MNGIE=mitochondrial neurogastrointestinal encephalomyopathy. MIRAS=mitochondrial recessive ataxia syndrome.
*
Each mitochondrial disease group was compared with all disease controls and healthy controls.
†
Calculated as 1000×(lactate/pyruvate).
‡
L:P was normal in all MIRAS patients and controls and, therefore, the positive predictive value could not be calculated.