Table 4.

Multivariate analysis of prognostic variables, serum M-spike response, and PCLI response

Prognostic variable	Proportional hazard ratio	95% CI	P
Initial PCLI ≥ 3%	2.71	1.52-4.62	.001*
Serum M-spike response < 50%	1.47	1.01-2.16	.047*
PCLI response < 60%	1.70	1.14-2.03	.009*
β2M > 3.5 mg/dL	1.33	0.87-2.03	.19
Creatinine > 1.4	1.20	0.76-1.88	.43

β₂M indicates β₂-microglobulin; CI, confidence interval; and PCLI, plasma cell labeling index.

^*Statistically significant.