Table 4. Assessment of bone marrow involvement.

Variables	Sensitivity	Specificity	PPV	NPV	95% CId	P valued
IgH PCRa	66.7	82.4	42.4	92.7	0.84–0.97	0.003
PET/CTb	55.6	87.1	45.6	91.0	0.86–0.95	0.001
IgH PCR or PET/CTa,c	85.2	71.7	37.0	96.1	0.90–0.99	0.001
IgH PCR and PET/CTa,c	37.0	97.0	70.6	88.8	0.86–0.91	0.001

PPV = positive predictive value, NPV = negative predictive value, CI = confidence interval, IgH = immunoglobulin heavy chain gene rearrangement, PCR = polymerase chain reaction, PET/CT = positron emission tomography-computed tomography.

^aValues shown in Table 2 were used for calculations as standard formulas for sensitivity, specificity, PPV, NPV.

^bTo evaluate the optimal cut-off value for PET/CT for detecting BMI, receiver operating characteristic analysis was performed using the area under the curve, Youden indexes. Optimal cut-off value was 1.0mCi and the area under the curve was 0.708.

^cParallel test was used to determine sensitivity, specificity of IgH PCR or PET/CT. Serial test was used to determine sensitivity and specificity of combined IgH PCR and PET/CT for detecting BMI.

^d95% CI and their P values for NPV were shown in Table 4.