TABLE 2.

Risk of bias assessment of the case control studies in this review, showing stars awarded for each domain.

Study	Selection	Comparability	Exposure
Edlow et al. (2007) 23	★★★☆	★ ☆	★★☆
Goldenberg et al. (1993) 24	★★★☆	★☆	★★★
Puyenbroek & Stolte (1983) 27	★★☆☆	★☆	★★★
Yang et al. (2023) 30	★☆☆☆	☆☆	★★☆