Table 2.

Summary of the clustered and weighted Cox proportional hazard model for survival^*

	Coefficient	Robust standard error	Z score	P value Unadjusted (Corrected†)	HR (95% CI)
Income level of residence
Low	Ref	–	–	–	1.00
Lower-middle	−0.18	0.22	−0.82	0.41 (1.00)	0.83 (0.54 – 1.29)
Upper-middle	−0.69	0.62	−1.11	0.27 (1.00)	0.50 (0.15 – 1.69)
High	−1.25	0.76	−1.64	0.10 (1.00)	0.29 (0.06 – 1.27)
All ages ‡
HR per month	0.03	0.02	1.81	0.07 (0.56)	1.03 (1.00 – 1.07)
HR per year	0.41	0.23	1.81	0.07 (0.56)	1.51 (0.96 – 2.35)
Age > 4 years
HR per month	−0.07	0.02	−2.89	0.004 (0.048)	0.94 (0.90 – 0.98)
HR per year	−0.79	0.27	−2.89	0.004 (0.048)	0.45 (0.27 – 0.78)
Laterality
Unilateral	Ref	–	–	–	1.00
Bilateral	0.52	0.36	1.46	0.14 (1.00)	1.68 (0.84 – 3.38)
Primary tumor
cT1	Ref	–	–	–	1.00
cT2	20.8	1.03	20.2	<0.001 (<0.001)	1.10×109 (1.46×108 – 8.26×109)
cT3	22.3	0.67	33.3	<0.001 (<0.001)	4.65×109 (1.25×109 – 1.72 × 1010)
cT4	24.8	–	–	–	5.98×1010 (No CI)
Sex
Male	Ref	–	–	–	1.00
Female	0.69	0.23	3.02	0.003 (0.04)	1.98 (1.27 – 3.10)
Family history of retinoblastoma
Negative	Ref	–	–	–	1.00
Positive	2.41	0.97	2.48	0.01 (0.16)	11.10 (1.66 – 74.8)
Hereditary retinoblastoma §
H0	Ref	–	–	–	1.00
H1	0.26	0.45	0.58	0.56 (1.00)	1.30 (0.54 – 3.13)

HR= hazard ratio

^*Overall, 43 observations were dropped from survival analysis because of missing observation time.

^†Corrected using Bonferroni method (multiplied by 12 for each model term).

^‡Age included in analysis as a continuous variable.

^§Hereditary refers to bilateral or trilateral retinoblastoma, positive family history, or positive blood RB1 mutation. H0= non-hereditary, H1= hereditary