Table 2

Dukes' stage distribution by covariable category, and before and after imputation

Characteristic	Stage at diagnosis
Characteristic	A	B	C	D	Unknown
Age at diagnosis
≤50	9.4	25.7	33.8	12.8	18.2
51–60	11.0	28.3	33.8	11.2	15.7
61–70	11.4	31.2	32.6	9.4	15.4
71–80	11.0	35.3	31.1	8.2	14.6
≥81	9.0	39.7	30.5	6.1	14.7
Sex
Male	11.1	32.9	31.7	8.8	15.5
Female	10.1	34.0	32.2	8.9	14.9
Operation
Elective	11.6	33.5	31.4	8.3	15.2
Emergency	1.8	31.9	37.3	14.2	14.8
IMD income category
Most affluent	11.5	32.3	32.0	8.7	15.5
2	11.2	33.3	32.1	8.6	14.8
3	10.4	34.2	31.8	8.7	14.9
4	10.2	33.5	32.0	8.8	15.6
Most deprived	9.8	33.5	31.7	9.7	15.4
Unknown^*	11.4	34.7	36.6	11.6	5.7
Cancer site
Colon	7.6	36.7	32.1	9.9	13.6
Rectosigmoid	11.8	30.7	33.3	10.0	14.3
Rectum	17.6	26.3	31.0	6.0	19.2
Year of diagnosis
1998	8.5	31.0	28.2	8.6	23.7
1999	10.1	30.9	30.3	8.9	19.9
2000	10.4	33.1	31.8	8.8	15.9
2001	11.3	34.7	32.8	9.9	11.4
2002	10.9	34.5	34.2	9.2	11.2
2003	11.2	33.9	32.6	8.7	13.6
2004	10.4	31.8	30.4	8.4	19.0
2005	11.5	35.1	34.5	8.7	10.2
2006	11.8	35.5	32.6	8.4	11.7
Charlson comorbidity score
0	10.9	33.1	31.8	9.0	15.3
1	8.2	34.7	33.7	8.7	14.7
2	10.6	35.5	31.9	7.6	14.5
3	9.2	37.4	31.9	6.1	15.5
Dukes' stage distribution
Before imputation (all)	10.7	33.4	31.9	8.9	15.2
Before imputation (staged cases only)	12.6	39.4	37.7	10.4	–
After imputation	12.7	39.5	37.4	10.4	–
Across imputed cases	13.5	40.0	36.3	10.1	–

↵* Index of Multiple Deprivation (IMD) income category information was missing in only a small proportion of cases (n=404, 0.25%).