Prior oral contraceptive use in ovarian cancer patients: assessing associations with overall and progression-free survival

Table 2 Multivariate analyses for overall survival and progression-free survival

Model	Oral contraceptive variable	N (events) for overall survival	Adjusted HR (95 % CI) for overall survival	P-Value	N (events) for progression-free survival	Adjusted HR (95 % CI) for progression – free survival	P-Value
All variables^a	Ever vs Never Users	880 (393)	0.82 (0.66, 1.03)	0.09	821 (481)	0.78 (0.64, 0.96)	0.02
	Duration of use
	1–48 months vs never	857 (383)	0.91 (0.70, 1.19)	0.27	800 (467)	0.71 (0.56, 0.91)	0.03
	>48 months vs never		0.80 (0.61, 1.05)			0.83 (0.66, 1.06)
	Duration of use as a continuous variable	857 (383)	0.998 (0.996, 1.00)	0.06	800 (467)	0.999 (0.997, 1.001)	0.22
Only the Statistically Significant Univariate Variables^b	Ever vs Never Users	950 (429)	0.89 (0.72, 1.10)	0.28	879 (520)	0.80 (0.66, 0.98)	0.03
	Duration of use
	1–48 months vs never	926 (418)	1.01 (0.78, 1.30)	0.35	858 (506)	0.74 (0.59, 0.94)	0.04
	>48 months vs never		0.84 (0.65, 1.10)			0.86 (0.68, 1.08)
	Duration of use as a continuous variable	926 (418)	0.998 (0.996, 1.000)	0.06	858 (506)	0.999 (0.997, 1.001)	0.17
Only the Statistically Significant Univariate Variables, Excluding Tumor Grade^c	Ever vs Never Users	1204 (511)	0.95 (0.78, 1.15)	0.57	1111 (619)	0.84 (0.70, 0.996)	0.046
	Duration of use	1173 (497)		0.80	1083 (601)		0.052
	1–48 months vs never		1.00 (0.79, 1.27)			0.77 (0.62, 0.95)
	>48 months vs never		0.93 (0.74, 1.18)			0.89 (0.72, 1.09)
	Duration of use as a continuous variable	1173 (497)	0.999 (0.997, 1.001)	0.19	1083 (601)	0.999 (0.998, 1.000)	0.15

^aAdjusted for all variables from Table 1 except for age at menarche, age at menopause, and platinum-based chemotherapy within 3 months, all of which were missing in approximately 450 patients
^bStatistically significant variables in univariate analyses include tumor stage, tumor type, tumor grade, debulking status after surgery, age at cancer diagnosis, and number of live births
^cTumor grade was excluded because it was missing in approximately 300 patients
NOTE: When age was excluded, all the oral contraceptive use models reached statistical significance (p < 0.05), except in the progression-free survival model that used continuous duration of oral contraceptive use as the key variable

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