Table 4.
Eligible articles quality assessment, following Fowkes and Fulton guidelines
| Guideline | Checklist | Urciuoli et al., 1998 [24] | Akça; Sahin, 2008 [10] | Bonan et al., 2008 [14] | Bodur; Cingil, 2009 [13] | Alcarde et al., 2010 [11] | Bodner et al., 2011 [12] | Ramos et al., 2012 [23] | Vitorino et al., 2013 [25] | Even-Zohar, 2014 [17] | Khoury; Sá-Neves, 2014 [19] | Dagios et al., 2015 [16] | Rachadel et al., 2015 [21] | Cucato et al., 2016 [15] | Herazo-Beltrán et al., 2017 [18] | Kuok et al., 2017 [20] | Ramocha et al., 2017 [22] |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Study design appropriate to objectives? | Cross-sectional | X | X | X | X | X | X | X | X | X | X | X | X | X | X | X | X |
| Cohort | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Controlled trial | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Case control | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Study sample representative? | Source of sample | 0 | 0 | 0 | + | ++ | 0 | 0 | 0 | 0 | 0 | ++ | 0 | 0 | 0 | 0 | 0 |
| Sampling method | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | + | 0 | |
| Sample size | ++ | 0 | ++ | 0 | ++ | 0 | 0 | ++ | 0 | ++ | 0 | 0 | 0 | 0 | 0 | ++ | |
| Entry criteria/ exclusions | + | ++ | + | ++ | ++ | + | + | + | ++ | + | + | + | + | + | + | 0 | |
| Non-respondents | 0 | 0 | 0 | 0 | 0 | + | 0 | 0 | 0 | 0 | ++ | 0 | 0 | 0 | + | 0 | |
| Control group accetable? | Definition of controls | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Source of controls | + | + | + | + | + | 0 | + | + | + | + | + | + | + | + | 0 | + | |
| Matching / randomisation | + | + | + | + | ++ | 0 | 0 | 0 | + | + | 0 | 0 | 0 | + | + | + | |
| Comparable characteristics | + | ++ | + | + | ++ | + | ++ | ++ | + | ++ | ++ | ++ | + | + | ++ | + | |
| Quality of measurements and outcomes? | Validity | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Reproducibility | + | + | + | + | + | + | + | + | + | + | + | + | + | 0 | + | + | |
| Blindness | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Quality control | + | ++ | + | 0 | + | + | + | + | + | + | 0 | + | 0 | 0 | 0 | + | |
| Completeness? | Compliance | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Drop outs | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Deaths | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Missing data | 0 | 0 | 0 | 0 | 0 | + | 0 | 0 | 0 | 0 | ++ | 0 | 0 | 0 | + | 0 | |
| Distorting influences? | Extraneous treatments | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Contamination | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Changes over time | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Confounding factors | + | ++ | + | + | ++ | + | ++ | ++ | + | ++ | ++ | ++ | + | + | + | + | |
| Distortion reduced by analysis | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | 0 | ++ | ++ | ++ | ++ | ++ | 0 | ++ | |
| Summary questions | Bias | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | No | Yes | Yes | Yes | Yes | Yes | No | Yes |
| Confounding | No | Yes | No | Yes | Yes | No | Yes | Yes | Yes | Yes | Yes | Yes | No | No | No | No | |
| Chance | Yes | Yes | Yes | No | Yes | No | Yes | Yes | No | Yes | Yes | Yes | No | No | No | Yes |
Notes: 0: No problem; +: Minor problem; ++: Major problem; NA: Not Applicable