Traffic-light plots showing the assessment of risk of bias using the Risk Of Bias In Nonrandomized Studies-of Exposures tool. (A) Studies considered for the evaluation of the association between SCT and CKD. (B) Studies considered for the determination of the pooled prevalence of SCT in patients with CKD/ESRD. Domains: D1, bias owing to confounding; D2, bias arising from measurement of the exposure; D3, bias in the selection of participants for the study (or the analysis); D5, bias owing to missing data; D6, bias arising from measurement of the outcome; and D7, bias in the selection of the reported result. D4 was not evaluated because patients with SCT do not receive any clinical care.