TABLE 3.

Distribution of protocol modifications and impact on outcome.

	Distribution			PFS		OS
Variable	CHOP‐19 (155 dogs)	CHOP‐25 (347 dogs)	P‐value	Hazard ratio	P‐value	Hazard ratio	P‐value
L‐asparaginase induction			.093	1.03	.846	1.04	.76
No	138 (89%)	287 (82.7%)
Yes	17 (11%)	60 (17.3%)
1st vincristine < 0.7 mg/m2			.279	1	.963	1.08	.49
No	117 (75.5%)	244 (70.3%)
Yes	38 (24.5%)	103 (29.7%)
1st cyclophosphamide <250 mg/m2			<.001*	0.96	.819	1.09	.61
No	151 (98.1%)	303 (87.3%)
Yes	3 (1.9%)	44 (12.7%)
1st doxorubicin < 30 mg/m2 (for dogs ≥ 15 kg)			.411	1.02	.917	1	1.0
No	88 (90.7%)	217 (86.8%)
Yes	9 (9.3%)	33 (13.2%)
1st doxorubicin <25 mg/m2 (for dogs <15 kg)			1	0.94	.704	0.97	.89
No	27 (56.2%)	52 (55.9%)
Yes	21 (43.8%)	41 (44.1%)
Vincristine RDI
All dogs (median [range])	0.91 (0.45‐2.26)	0.92 (0.33‐4.26)	.117	7.04	<.001*	4.33	<.001*
Completed protocols (median [range])	0.88 (0.48‐1.06)	0.89 (0.33‐1.48)	.518	2.17	.128	2.09	.18
Cyclophosphamide RDI
All dogs (median [range])	0.96 (0.6‐4.5)	0.9 (0.25‐5.86)	.112	2.56	<.001*	2.09	<.001*
Completed protocols (median [range])	0.93 (0.6‐1.11)	0.87 (0.44‐1.46)	.01*	5.64	<.001*	3.91	.01*
Doxorubicin RDI
All dogs (median [range])	0.88 (0.38‐2.43)	0.93 (0.25‐2.16)	.014*	4.73	<.001*	2.32	.001*
Completed protocols (median [range])	0.91 (0.46‐1.17)	0.93 (0.3‐1.45)	.241	1.86	.176	1.44	.48
Number of dose delays			.005*	0.87	<.001*	0.9	.003*
Median (range)	0 (0‐6)	1 (0‐10)
Number of dose reductions			.008*	0.9	<.001*	0.95	.03*
Median (range)	0 (0‐6)	1 (0‐12)

Abbreviations: CHOP, C = cyclophosphamide, H = hydroxydaunorubicin (Doxorubicin), O = Oncovin, P = prednisolone; PFS, progression‐free survival; OS, overall survival; RDI, relative dose intensity.

^*Significant differences (P < .05).