Table 4 –

Multivariable associations between baseline factors and outcomes (grades 2–3)^a,b

			Acute					Late
			N (%)	OR	95% CI		p value	N (%)	OR	95% CI		p value
Any GI toxicity	Prostate volume			0.98	0.94–	1.02	0.31		0.99	0.97–	1.02	0.55
	Age at SBRT (yr)			0.91	0.83–	0.99	0.028		0.98	0.92–	1.04	0.45
	Hormone therapy	Yes	3 (2)	1.14	0.29–	4.46	0.85	3 (2)	0.43	0.12–	1.48	0.18
		No	7 (2)	REF				18 (5)	REF
	Rectal spacer	Yes	2 (1)	0.26	0.05–	1.22	0.09	4 (1)	0.24	0.08–	0.71	0.010
		No	8 (3)	REF				17 (6)	REF
Any GU toxicity	Prostate volume			1.01	0.99–	1.02	0.42		1.01	1.00–	1.01	0.24
	Age at SBRT (yr)			1.02	0.98–	1.06	0.35		1.00	0.98–	1.03	0.79
	Hormone therapy	Yes	20 (13)	1.41	0.80–	2.51	0.24	34 (23)	0.92	0.59–	1.44	0.71
		No	39 (10)	REF				96 (24)	REF
	Rectal spacer	Yes	24 (9)	0.69	0.40–	1.20	0.19	40 (15)	0.37	0.25–	0.57	<0.001
		No	35 (12)	REF				90 (32)	REF
	IPSS baseline score			1.04	0.99–	1.09	0.09		1.09	1.05–	1.13	<0.001
	IPSS baseline score (grouped)	≥15	7 (12)	1.13	0.49–	2.61	0.78	20 (34)	1.76	0.99–	3.15	0.055
		<15	52 (11)	REF				110 (23)	REF

CI = confidence interval; GI = gastrointestinal; GU = genitourinary; IPSS = International Prostate Symptom Score; N = total number for level; OR = odds ratio; REF= reference; SBRT = stereotactic body radiotherapy.

^aModels assess probability of experiencing toxicity: OR >1 indicates higher odds of toxicity; OR <1 indicates lower odds of toxicity.

^bFor continuous factors, odds ratio corresponds to a one-unit increase.