GSTM1 and anemia: In the anemia subgroup with Hb < 7.0 g/dL, the SpHb measurement had a consistently higher bias of 1.97 (95% confidence interval, CI: 1.42–2.52), 2.06 (95% CI: 1.67–2.44), and 1.62 (95% CI: 1.32–1.92) for the normal, mild, and severe hyperbilirubinemia groups, respectively.