Table 3.
Risk of bias and quality assessment of included studies using the Newcastle–Ottawa Scale (NOS).
| Study | Study design | Selection (max 4) | Comparability (max 2) | Exposure/ Outcome (max 3) | Total Score/9 | Quality rating |
|---|---|---|---|---|---|---|
| Kim et al. (22) | Case–control | ★★★★ | ★★ | ★★ | 8 | Low risk (good quality); validated GC–MS exposure ascertainment |
| Durmaz et al. (23) | Case–control | ★★★★ | ★★ | ★★ | 8 | Low risk (good quality); creatinine-adjusted BPA measurement |
| Lee et al. (24) | Cross-sectional | ★★ | ★★ | ★★ | 6 | Moderate risk; cross-sectional exposure–outcome assessment limits temporality |
| Supornsilchai et al. (25) | Case–control | ★★★★ | ★★ | ★★ | 8 | Low risk (good quality); high-sensitivity LC–MS/MS method |
| Jung et al. (26) | Case–control | ★★★★ | ★★ | ★★ | 8 | Low risk (good quality); multicenter recruitment |
| Chen et al. (27) | Case–control | ★★★★ | ★★ | ★★ | 8 | Low risk (good quality); matched design and internal QC |
| Mohsen et al. (28) | Cross-sectional | ★★ | ★★ | ★★ | 6 | Moderate risk; limited adjustment for confounders |
| Durmaz et al. (29) | Case–control | ★★★★ | ★★ | ★★ | 8 | Low risk (good quality); clinically well-defined PT cases |
| Vu Huynh et al. (30) | Case–control | ★★★★ | ★★ | ★★ | 8 | Low risk (good quality); large sample size and recent data |
★ indicates a point awarded for meeting a specific NOS criterion. NOS, Newcastle–Ottawa Scale; HPLC, high-performance liquid chromatography; LC–MS/MS, liquid chromatography–tandem mass spectrometry; UPLC–MS/MS, ultra-performance liquid chromatography–tandem mass spectrometry; GC–MS, gas chromatography–mass spectrometry; CPP, central precocious puberty; BMI, body mass index.