Observations D-Bil >0.3 % T-Bil0 to 0.8 11861 52 0.4 T-Bil0 to 0.9 12623 106 0.8 T-Bil0 to 1.0 13209 174 1.3 T-Bil0 to 1.1 13608 248 1.8 T-Bil>1.1 2434 1439 59.1 T-Bil = Total bilirubin in mg/dL; D-Bil = direct bilirubin in mg/dL

Table 8: The numbers presented in table 7 are a conservative case for not performing direct bilirubin when total bilirubin is <0.9 mg/dL as the percentage of observations with direct bilirubin >0.3 mg/dL is only 0.4% when total bilirubin is <0.9 mg/dL. If we examine the percentage of patients with total bilirubin up to 1.1 mg/dL, only 1.8% had direct bilirubin exceeding 0.3 mg/dL. However the rate of direct bilirubin exceeding 0.3 mg/dL in patients with total bilirubin of 0.9 mg/dL is a clinically meaningful 7.1%, and in those with total bilirubin of 1.0 mg/dL the rate is, as expected, even higher at 11.6%. Therefore, despite the low prevalence of direct bilirubin >0.3 mg/dL in patients with total bilirubin of up to 1.1 mg/dL, it would be prudent to perform reflex testing for direct bilirubin when total bilirubin is ≥ 9.0 mg/dL