Recruiting former melanoma patients via hospitals in comparison to office-based dermatologists in a register-based cohort study that required indirect contact

Table 3 Comparison between study participants and non-participants in terms of patients’ social demographics and disease characteristics

	Participants (n = 689)						Non-participants (n = 1012)^c		p-value⁴
	Early responder (n = 401)^a		Late responder (n = 288)^b		All participants (n = 689)
	n	%	n	%	n	%	n	%
Sex									0.03
Male	197	49.1	138	47.9	335	48.6	438	43.3
Female	204	50.9	150	52.1	354	51.4	574	56.7
Cancer stage at time of diagnosis (UICC) (Register data)^d									0.15
Stage I	205	51.1	160	55.6	365	53.0	492	48.6
Stage II	17	4.2	17	5.9	34	4.9	68	6.7
Stage III	4	1.0	3	1.0	7	1.0	16	1.6
Stage IV	0	0	0	0	0	0	3	0.3
unknown	175	43.6	108	37.5	283	41.1	433	42.8
Localization at time of diagnosis (ICD-10) (Register data)									0.13
C43.6 + C43.7: Extremities	193	48.1	136	47.2	329	47.8	502	49.6
C43.2-C43.4: Head−/ Neck-Area	50	12.5	43	14.9	93	13.5	168	16.6
C43.5: Trunk	148	36.9	100	34.7	248	36.0	317	31.3
C43.8+ C43.9: Unspecified/Overlapping Areas	10	2.5	9	3.1	19	2.8	25	2.5
Place of residence									0.08
Urban	289	72.1	207	71.9	496	72.0	687	67.9
Rural	112	27.9	81	28.1	193	28.0	325	32.1
Age at end of recruitment (years)^e									< 0.0001
Median	62.0		63.0		62.0		69.0
Lower Quartile	50.0		50.0		50.0		51.0
Upper Quartile	73.0		74.5		74.0		79.0
Time since diagnosis (years)^f									0.18
Median	9.0		9.0		9.0		9.0
Lower Quartile	7.0		8.0		8.0		8.0
Upper Quartile	11.0		10.0		10.0		10.0

⁴Comparison of participants and non-participants: Chi²⁻Test and Fisher’s Exact Test (categorical variables); Median Test (continuous variables)
^aParticipation after first mail-out, percentages refer to all participants (n = 689)
^bUp to 7 reminders after first mail-out, percentages refer to all participants (n = 689)
^cTotal register-based sample: n = 2112, percentages refer to all non-participants (n = 1012)
^dUICC-Stage: For year of diagnosis up to 2003 according to TNM 5th edition (German version, Springer Verlag 1997), for year of diagnosis 2004 or later according to TNM 6th edition (German version, Springer Verlag 2002); Subdivisions according to TNM 6 in A or B were summarized in respective stages
^eAge at termination of recruitment (15.05.2012): Difference between date of birth and end of recruitment
^fPeriod of time between date of diagnosis by month and termination of recruitment

ISSN: 1471-2288