Table 2 Summary of outcome of subgroup analysis of various metabolites between patient with Alzheimer’s disease (AD) and healthy controls (HC)
Metabolites | No. of studies | No. of AD | N of HC | Heterogeneity test | I2 (%) | Model | Effect estimate (95% CI) | Test(s) of P = 0 | ||
|---|---|---|---|---|---|---|---|---|---|---|
Chi2 | P-value | Z | P-value | |||||||
Concentration | ||||||||||
NAA | 6 | 326 | 417 | 2.15 | 0.83 | 0 | Fixed | − 0.91 [− 1.05, − 0.77] | 12.47 | < 0.00001 |
Cr | 2 | 169 | 97 | 5.36 | 0.02 | 81 | Random | − 0.33 [− 0.81, 0.15] | 1.33 | 0.18 |
Cho | 4 | 235 | 316 | 0.64 | 0.84 | 0 | Fixed | 0.03 [− 0.01, 0.07] | 1.67 | 0.89 |
mI | 5 | 302 | 370 | 1.10 | 0.89 | 0 | Fixed | 0.32 [0.19, 0.46] | 4.65 | < 0.00001 |
Glu | 3 | 90 | 266 | 0.37 | 0.83 | 0 | Fixed | − 0.75 [− 1.00, − 0.50] | 5.87 | < 0.00001 |
GLx | 4 | 189 | 311 | 7.66 | 0.05 | 61 | Random | − 0.67 [− 1.13, − 0.20] | 2.80 | 0.005 |
Ratio | ||||||||||
NAA/Cr | 14 | 491 | 735 | 174.71 | < 0.00001 | 93 | Random | − 0.15 [− 0.20, − 0.09] | 5.30 | < 0.00001 |
Cho/Cr | 13 | 464 | 739 | 54.16 | < 0.00001 | 78 | Random | 0.05 [0.03, 0.06] | 5.38 | < 0.00001 |
mI/Cr | 16 | 632 | 1005 | 104.68 | < 0.00001 | 86 | Random | 0.10 [0.08, 0.13] | 8.66 | < 0.00001 |
mI/NAA | 7 | 266 | 367 | 162.48 | < 0.00001 | 96 | Random | 0.17 [0.04, 0.30] | 2.51 | 0.01 |
NAA/mI | 1 | 47 | 56 | – | – | – | – | – | – | – |
sI/Cr | 1 | 15 | 19 | – | – | – | – | – | – | – |
Glu/Cr | 1 | 30 | 26 | – | – | – | – | – | – | – |
mI/Cho | 1 | 30 | 15 | – | – | – | – | – | – | – |