Cause of death for patients with breast cancer: discordance between death certificates and medical files, and impact on survival estimates

Table 3 Agreement analyses (kappa statistic) for different patient subgroups (grouped based on patient and tumor characteristics), comparing principal cause of death from death certificates and medical files

Category	Subgroups	Number of patients alive	Number of deceased patients (FU 31-12-2016)	Kappa statistic	Spearman’s correlation coefficient and p-value
Age	<40 years	177	11	ND^a	Rho= -0.7 P-value= 0.23
	40-49	525	37	0.64
	50-59	736	42	0.83
	60-69	649	60	0.73
	70-79	334	89	0.54
	≥80	87	115	0.50
Year of diagnosis	2009	393	96	0.77	Rho= -0.26 P-value= 0.67
	2010	379	69	0.59
	2011	398	70	0.71
	2012	429	54	0.67
	2013	472	28	0.78
	2014	437	37	0.54
Stage at diagnosis	Stage 0	46	1	ND^a	Rho= -0.8 P-value= 0.33
	Stage I	1019	44	0.76
	Stage II	1053	121	0.69
	Stage III	288	69	0.75
	Stage IV	56	102	0.35
	Stage unknown^b	46	17	0.43
Grade of tumor	Grade 1	301	18	ND^a	ND^c
	Grade 2	1223	155	0.58
	Grade 3	960	166	0.81
	Grade unknown^b	24	15	0.86
Multiple tumors	Yes	94	35	0.66	ND^c
Multiple tumors	No	2414	319	0.69	ND^c

ISSN: 2049-3258