Table 1.
Vote counting based on the direction of the relationship between lead concentration and red blood cell parameters.
| Reference | Study | Sample size | Study quality |
RBC count
(n = 7) |
HCT
(n = 8) |
HB
(n = 33) |
MCV
(n = 9) |
MCH
(n = 8) |
MCHC
(n = 7) |
RDW
(n = 5) |
|---|---|---|---|---|---|---|---|---|---|---|
| (23) | Guo et al. 2021 | 17486 | Good | ▾ | ||||||
| (24) | Hegazy et al. 2010 | 60 | Good | ▴ | ▾ | ▾ | ▾ | ▾ | ▾ | ▴ |
| (30) | Kutllovci-Zogaj et al. 2014 | 250 | Good | ▾ | ||||||
| (32) | Liu et al. 2012 | 140 | Good | ▾ | ||||||
| (35) | Mitra et al. 2012 | 559 | Good | ▾ | ||||||
| (38) | Ngueta, 2016 | 3799 | Good | ▴ | ▴ | ▾ | ||||
| (41) | Rondó et al. 2011 | 384 | Good | ▾ | ||||||
| (47) | Zolaly et al. 2012 | 235 | Good | ▾ | ||||||
| (51) | Irawati et al. 2022 | 128 | Fair | ▴ | ||||||
| (26) | Keramati et al. 2013 | 223 | Fair | ▾ | ▴ | ▾ | ▾ | |||
| (27) | Khan et al. 2010 | 246 | Fair | ▾ | ||||||
| (31) | Li et al. 2018 | 743 | Fair | ▾ | ▾ | ▾ | ||||
| (33) | Liu et al. 2015 | 855 | Fair | ▾ | ▾ | |||||
| (42) | Ruiz-Tudela et al. 2021 | 1427 | Fair | ■ | ▴ | |||||
| (45) | Wang et al. 2012 | 4429 | Fair | ▾ | ||||||
| (46) | Ye et al. 2015 | 1047 | Fair | ▾ | ||||||
| (20) | Alvarez-Ortega et al. 2017 | 118 | Poor | ▴ | ▾ | ▾ | ▾ | ▾ | ▾ | ▴ |
| (21) | Alvarez-Ortega et al. 2019 | 554 | Poor | ▴ | ▴ | ▴ | ▴ | ▾ | ▾ | ▴ |
| (50) | Banga et al. 2021 | 81 | Poor | ▴ | ||||||
| (22) | Dai et al. 2017 | 332 | Poor | ■ | ■ | ■ | ■ | ■ | ■ | ▴ |
| (25) | Hoang et al. 2021 | 403 | Poor | ▾ | ||||||
| (28) | Kordas et al. 2010 | 222 | Poor | ▴ | ||||||
| (29) | Kuang et al. 2020 | 395 | Poor | ▴ | ▾ | ▾ | ▾ | ▾ | ▴ | |
| (34) | Mitchell et al. 2012 | 67 | Poor | ■ | ||||||
| (48) | Moawad et al. 2016 | 300 | Poor | ▾ | ||||||
| (36) | Mohan et al. 2014 | 226 | Poor | - | ||||||
| (37) | Nassef et al. 2014 | 90 | Poor | ▾ | ||||||
| (39) | Queirolo et al. 2010 | 222 | Poor | ▾ | ||||||
| (19) | Rasoul et al. 2012 | 180 | Poor | ▾ | ||||||
| (40) | Rawat et al. 2021 | 43 | Poor | ▾ | ▾ | ▾ | ▾ | ▾ | ▾ | ▴ |
| (43) | Reddy et al. 2011 | 195 | Poor | ▾ | ||||||
| (49) | Shah et al. 2010 | 340 | Poor | ▾ | ||||||
| (44) | Wang et al. 2021 | 426 | Poor | ▾ | ||||||
| Proportion of negative relationships (95%CI) | ||||||||||
| All studies | 0.286 (0.065, 0.648) | 0.625 (0.295, 0.881) | 0.750 (0.583, 0.874) | 0.556 (0.254, 0.827) | 0.875 (0.546, 0.986) | 0.714 (0.352, 0.935) | 0.000 (0.000, 0.379) | |||
| Excluding conflicting results | 0.333 (0.077, 0.714) | 0.714 (0.352, 0.935) | 0.828 (0.663, 0.931) | 0.625 (0.295, 0.881) | 1.000 (0.708, 1.000) | 0.833 (0.442, 0.981) | 0.000 (0.000, 0.379) | |||
| Only good quality studies | 0.000 (0.000, 0.853) | 0.500 (0.061, 0.939) | 0.875 (0.546, 0.986) | 1.000 (0.333, 1.000) | 1.000 (0.147, 1.000) | 1.000 (0.147, 1.000) | 0.000 (0.000, 0.853) | |||
RBC, red blood cell; HCT, hematocrit; HB, hemoglobin; MCV, mean corpuscular volume; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration; RDW, red cell distribution width; CI, confidence interval.
▴, positive relationship; ▾, negative relationship; ■, conflicting results/no direction; -, no information available.
Bolds represent evidence of a relationship.