Table 4. Multivariate analysis correlating radiation dose to brachial plexus with nodal category.

	No. of brachial plexuses	Univariate		Multivariate*		Multivariate†		Multivariate‡
		Mean	SE	Mean	SE	Mean	SE	Mean	SE
Minimum dose (Gy)
N0–N1	77	19.5	1.2	19.5	1.2	21.8	0.99	19.6	1.2
N2–N3	148	28.0	0.88	28.0	0.88	26.8	0.71	28.0	0.87
p Value		<0.0001		<0.0001		<0.0001		<0.0001
Maximum dose (Gy)
N0–N1	77	52.8	1.3	53.1	1.3	54.0	1.3	52.7	1.3
N2–N3	148	60.9	0.95	60.7	0.91	60.3	0.93	61.0	0.95
p Value		<0.0001		<0.0001		0.0001		<0.0001
Mean dose (Gy)
N0–N1	77	36.5	1.2	36.8	1.2	38.3	1.1	36.5	1.2
N2–N3	148	45.2	0.87	45.0	0.84	44.2	0.78	45.2	0.87
p Value		<0.0001		<0.0001		<0.0001		<0.0001

Abbreviation: SE = standard error.

^*Adjusting for brachial plexus volume.

^†Adjusting for use of low anterior neck (LAN) field.

^‡Adjusting for tumor category (note: Analysis retained significance after adjusting for treatment intent and total radiation dose).