Table 2 Characteristics of studies included in meta-analysis
Reference; country | Tear sample collection method | Method of quantification | Participants in the Control group | Participants in the Diabetes group | Participants in the Complications group | Reported biomarkers | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Number of participants | Sex | Age (years) Presented as mean ± SD or range or median (IQR) | Number of participants | Sex | Age (years) Presented as mean ± SD or range or median (IQR) | Complication; number of participants | Sex | Age (years) Presented as mean ± SD or range or median (IQR) | ||||
Mei et al [37]; China | Capillary collection strip | Electrochemical platform; ELISA | 5 | - | - | - | - | - | DR: 5 | - | - | VEGF |
Sorkhabi et al [41]; Iran | Capillary tube | ELISA | 20 | 8 M and 12 F | 46.05+13 | 20 | 12 M and 8 F | 47.75+5.6 | NPDR: 25; PDR: 25 | NPDR: 13 M and 12 F; PDR: 10 M and 15 F | NPDR: 52.04+8.7; PDR: 52.92+10.1 | TNF-α, IL-8 and IL-1RA |
Liu et al [42]; China | Glass capillary tube | ELISA; mulitplex cytokine analysis | 15 | 8 M and 7 F | 59+2.42 | 15 | 8 M and 7 F | 61.27+1.95 | DR: 15 | 7 M and 8 F | 61.07±2.16 | IL-1β, IL-1RA, IL-6, IL-8, IL-10, VEGF and MCP-1 |
Azhan et al [43]; Malaysia | Schirmer strip | ELISA | 33 | 19 M and 14 F | 69.6+7.5 | - | - | - | NPDR: 32 | 18 M and 14 F | 67.3+7.0 | VEGF |
Ang et al [52]; USA | Schirmer strip | Human immunoassay kit | - | - | - | 30 | 17 M and 13 F | 64.6+8.8 | NPDR: 28; PDR: 30 | NPDR: 11 M and 17 F; PDR: 16 M and 14 F | NPDR: 58.5+8.2; PDR: 52.3+9.6 | VEGF |
Kim et al [44]; South Korea | Capillary tube | Multiplex immunobead assay; magnetic luminex screening assay | 30 | 15 M and 15 F | 67.5 (60–72) | 30 | 7 M and 23 F | 70 (63–74) | - | - | - | MCP-1, IL-6, IL-8, and VEGF |
Manchikanti et al [38]; India | 10 μl micropipette tip attached to a plastic pipette | ELISA | 21 | 19 M and 2 F | 51.33±10.683 | - | - | - | NPDR: 10; PDR: 11 | 19 M and 2 F | 54.59±11.58 | TNF-α and IL-1β |
Amorim et al [26]; Portugal | Schirmer I test | BCA protein assay kit; LC-MS/MS; multiplex analysis | 12 | 3 M and 9 F | 54±11 | 13 | 7 M and 6 F | 59±11 | NPDR: 25; PDR: 16 | NPDR: 18 M and 7 F; PDR: 13 M and 3 F | NPDR: 65±9; PDR: 66±6 | IL-1β and IL-6 |
Byambajav et al [39]; UK | Glass capillary micropipette | Magnetic bead panel | 17 | 6 M and 11 F | 52+16 | 41 | 25 M and 16 F | 62+21 | DED: 47 | 29 M and 18 F | 64+16 | IL-6, TNF-α, VEGF, IL-1β, IL-1RA, and IL-8 |
Zhou et al [45]; China | Glass capillary tube | Immune bead–based array | 22 | 10 M and 12 F | 57.32±9.66 | - | - | - | DR: 48 | 29 M and 19 F | 59.15 ± 9.51 | TNF-α and IL-6 |
Liu et al [40]; China | Glass capillary micropipette | Multiplex bead analysis | 29 | 5 M and 24 F | 62.4±7.5 | 24 | 7 M and 17 F | 63.5±10.1 | DED: 32 | 14 M and 18 F | 61.8±9.8 | TNF-α and IL-1β |
Hashemi et al [46]; Iran | Schirmer's standard strip | ELISA | 30 | 15 M and 15 F | 56.90±8 | 30 | 16 M and 14 F | 58.8±7.74 | DR: 30 | 14 M and 16 F | 62.2±7.0 | VEGF |
Machalińska et al [47]; Poland | Schirmer's standard strip | Multiplex fluorescent bead-based immunoassays, High sensitivity cytokine assay | 52 | 25 M and 27 F | 63+12 | - | - | - | DR: 52 | 35 M and 17 F | 65+11.5 | TNF- α, VEGF, IL-1β, IL-6, and IL-8 |
Sheikhrezaee et al [28]; Iran | Schirmer's standard strip | ELISA | 30 | 15 M and 15 F | 56.9±8 | 30 | 16 M and 14 F | 58.8±7.8 | DR: 30 | 14 M and 16 F | 62.2±7 | VEGF |
Costagliola et al [27]; Italy | Schirmer's standard strip | ELISA | 16 | 8 M and 8 F | 53 (47-58) | - | - | - | NPDR: 16; PDR: 16 | NPDR: 9 M and 7 F; PDR: 10M and 6 F | NPDR: 54 (49-67); PDR: 59 (52-73) | TNF-α |
Amil-Bangsa et al [48]; Malaysia | Glass capillary tube | ELISA | - | - | - | 15 | 8 M and 7 F | 58.3±4.8 | Mild NPDR: 15; moderate NPDR: 15; severe NPDR: 15 | Mild: 6 M and 9 F, moderate: 9 M and 6 F; severe 12 M and 3 F | Mild: 57.0±4.8; moderate: 58.9±4.7; severe: 57.5±4.8 | TNF-α |
Stolwijk et al [49]; Netherlands | Glass capillary tube | Bradford's assay, HPLC, SDS-PAGE | 26 | - | 39.7+11.5 | 25 | - | 33.4+12.1 | DR: 29 | - | 46.3+10.4 | LTF and LZM |
Zou et al [50]; China | Schirmer I test | TMT Labeling, HPLC, LC-MS | 5 | 2 M and 3 F | 54.80±6.06 | - | - | - | DED: 10 | 4 M and 6 F | 55.50±4.79 | LTF and LZM |
Yu et al [51]; China | Glass microcapillary tube | Lowry method, SDS-PAGE | 67 | 32 M and 35 F | - | - | - | - | NPDR: 70; PDR: 63 | NPDR: 36 M and 34 F; PDR: 31 M and 35 F | - | LTF and LZM |
Total participants: 1413 | 430 | 273 | 710 | |||||||||