Table 3.
Absolute risk and Cox proportional hazards models for overall, sex-stratified and age-stratified analyses in IDA analytic cohort
| Cohort characteristics | Absolute estimates | Cox proportional hazards models | ||||||
| Baseline at risk (N) |
Number of YCRC cases | 5-year cumulative incidence % (95% CI) | Risk difference % (95% CI) | NNS (95% CI) | Unadjusted HR (95% CI) |
Adjusted HR (95% CI) |
||
| Overall | IDA | 47 800 | 184 | 0.45 (0.38–0.51) |
0.39 (0.33–0.46) |
259.8 (226.8–301.6) |
10.35 (7.89–13.57) |
10.81 (8.15–14.33) |
| No IDA | 191 200 | 73 | 0.05 (0.04–0.07) |
|||||
| Ages <30 years | IDA | 4925 | 7 | 0.14 (0.04–0.27) |
0.14 (0.04–0.26) |
703.6 (377.2–2422) |
29.22 (3.59–237.47) |
147.67 (3.43–6350.88) |
| No IDA | 20 505 | 1 | 0.01 (0.00–0.02) |
|||||
| Ages 30–39 years | IDA | 12 255 | 21 | 0.20 (0.12–0.28) |
0.18 (0.10–0.26) |
583.6 (399.2–943.8) |
14.53 (5.86–36.00) |
14.00 (5.48–35.76) |
| No IDA | 50 152 | 6 | 0.02 (0.00–0.03) |
|||||
| Ages 40–49 years | IDA | 30 620 | 156 | 0.61 (0.51–0.72) |
0.53 (0.41–0.63) |
196.3 (171.1 –235.9) |
9.62 (7.21–12.83) |
10.06 (7.47–13.56) |
| No IDA | 120 543 | 66 | 0.09 (0.07–0.11) |
|||||
| Men | IDA | 22 445 | 160 | 0.85 (0.72–1.00) |
0.78 (0.64–0.92) |
140.3 (121.5–165.6) |
14.04 (10.17–19.39) |
14.00 (10.04–19.54) |
| No IDA | 89 780 | 48 | 0.08 (0.06–0.11) |
|||||
|
Men,
aged <30 years |
IDA | 1235 | 7 | 0.58 (0.17–1.04) |
0.56 (0.15–1.00) |
176.4 (95.2–625) |
29.44 (3.62–239.31) |
38.76 (4.50–334.13) |
| No IDA | 5141 | 1 | 0.02 (0.00–0.06) |
|||||
|
Men,
aged 30–39 years |
IDA | 3812 | 13 | 0.37 (0.28–0.58) |
0.34 (0.14–0.55) |
293.2 (185.2–625) |
14.35 (4.68–44.02) |
11.96 (3.76–38.08) |
| No IDA | 16 201 | 4 | 0.03 (0.01–0.07) |
|||||
|
Men,
aged 40–49 years |
IDA | 17 398 | 140 | 1.02 (0.84–1.19) |
0.91 (0.74–1.09) |
124.3 (106.4–149.3) |
13.56 (9.64–19.09) |
13.95 (9.81–19.85) |
| No IDA | 68 438 | 43 | 0.10 (0.07–0.14) |
|||||
| Women | IDA | 25 355 | 24 | 0.11 (0.07–0.17) |
0.08 (0.03–0.13) |
1056.5 (741–1692) |
3.85 (2.20–6.74) |
4.24 (2.34–7.69) |
| No IDA | 101 420 | 25 | 0.03 (0.02–0.05) |
|||||
|
Women,
aged <30 years |
IDA | 3690 | 0 | |||||
| No IDA | 15 364 | 0 | ||||||
|
Women,
aged 30–39 years |
IDA | 8443 | 8 | 0.12 (0.04–0.22) |
0.11 (0.03–0.21) |
1055.4 (588.2–2500) |
16.09 (3.42–75.76) |
13.99 (2.76–70.85) |
| No IDA | 33 951 | 2 | 0.01 (0.00–0.02) |
|||||
|
Women,
aged 40–49 years |
IDA | 13 222 | 16 | 0.14 (0.07–0.22) |
0.07 (0.00–0.16) |
826.4 (555.6–1428.6) |
2.74 (1.45–5.19) |
3.23 (1.65–6.31) |
| No IDA | 52 105 | 23 | 0.07 (0.04–0.10) |
|||||
Risk difference corresponds to difference between exposed and unexposed cumulative incidence results. Number needed to scope (NNS) is the inverse of the CRC prevalence among exposed individuals.
Absolute estimates derived from 5-year cumulative incidence curve models accounting for censoring with bootstrapped 95% CIs.
Unadjusted model includes matching strata variable as random intercept; adjusted model additionally adjusts for race/ethnicity, BMI, prevalent diabetes, smoking status and aspirin use.
Empty cells reflect having zero cases, limiting the ability to conduct stratified analyses.
BMI, body mass index; CRC, colorectal cancer; IDA, iron-deficiency anaemia; YCRC, young-onset colorectal cancer.