Table 1.

Characteristics of the uveal melanoma case patients and control subjects of the RIFA case-control study

	Cases		Controls
			Population		Ophthalmologist*		Sibling†
	N	%	N	%	N	%	N	%
Eligible	486	100	1510	100	348	100	330	100
Responder	461	95	847	56	180	52	187	57
Interviewed/partly interviewed	459	94	827	55	180	52	187	57
only questionnaire	2	0	20	1	0	0	0	0
Nonresponder	25		663		168		143
nonresponder questionnaire	10	2	284	19	23	7	5	2
no nonresponder questionnaire	15	3	379	25	145	42	138	42
Characteristics of cases and controls included in the analyses	459	100	827	100	180	100	187	100
Sex
men	243	53	454	55	103	57	81	43
women	216	47	373	45	77	43	106	57
Age at reference date
20-49	90	20	159	19	25	14	53	28
50-59	111	24	194	24	46	26	41	22
60-69	192	42	374	45	79	44	84	45
70-74	66	14	100	12	30	17	9	5
Place of residence
Northern region 1	75	16	130	16	38	21	32	17
Northrhine-Westphalia2	187	41	362	44	74	41	71	38
Midwestern region3	92	20	162	20	36	20	34	18
Southern region4	91	20	146	18	30	17	33	18
Eastern region5	14	3	27	3	2	1	13	7
Region missing	0	0	0	0	0	0	4	2

Due to rounding, the sum of the percentages may not necessarily exactly add up to 100%

* Ophthalmologists' controls were recruited only for cases diagnosed the first year of case recruitment (until September 24, 2003)

^† Cases without eligible siblings could not contribute controls to the study

1) Schleswig-Holstein, Lower Saxony, Hamburg, Bremen 2) only Northrhine-Westphalia 3) Hesse, Rhineland Palatinate, Saarland

4) Baden-Württemberg, Bavaria 5) Berlin, Brandenburg, Saxony Anhalt, Saxony, Thuringia, Mecklenburg-West Pomerania