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Table 2 Frequency distribution of comorbidities, lifestyle factors and healthcare use of CRC cases and controls, and their association with risk of CRC

From: New use of low-dose aspirin and risk of colorectal cancer by stage at diagnosis: a nested case–control study in UK general practice

Characteristic Controls
N = 10,000
n (%)
Cases
N = 3033
n (%)
RR (95% CI)a
PCP visitsb
 0–1 486 (4.9) 92 (3.0) 1.00 (−)
 2–4 1094 (10.9) 261 (8.6) 1.37 (1.06–1.79)
 5–9 2624 (26.2) 699 (23.0) 1.76 (1.38–2.25)
 10–19 3715 (37.1) 1164 (38.4) 2.28 (1.79–2.91)
 ≥ 20 2081 (20.8) 817 (26.9) 3.07 (2.38–3.96)
Referralsb
 0–1 4760 (47.6) 1182 (39.0) 1.00 (−)
 2–4 2778 (27.8) 917 (30.2) 1.28 (1.16–1.43)
 5–9 1716 (17.2) 612 (20.2) 1.35 (1.19–1.53)
 ≥ 10 746 (7.5) 322 (10.6) 1.57 (1.33–1.85)
Hospitalizationsb
 None 8496 (85.0) 2424 (79.9) 1.00 (−)
 1 930 (9.3) 375 (12.4) 1.32 (1.16–1.51)
 2 328 (3.3) 148 (4.9) 1.45 (1.18–1.77)
 ≥ 3 246 (2.5) 86 (2.8) 1.08 (0.83–1.39)
BMI (kg/m2)c
 < 20 343 (3.4) 111 (3.7) 1.07 (0.85–1.35)
 20–24 2665 (26.7) 774 (25.5) 1.00 (−)
 25–29 3793 (37.9) 1144 (37.7) 1.03 (0.93–1.15)
 ≥ 30 2324 (23.2) 714 (23.5) 1.04 (0.92–1.17)
 Unknown 875 (8.8) 290 (9.6) 1.25 (1.06–1.47)
Smoking status
 Non-smoker 4378 (43.8) 1231 (40.6) 1.00 (−)
 Current 1292 (12.9) 376 (12.4) 1.07 (0.94–1.23)
 Former 4102 (41.0) 1362 (44.9) 1.20 (1.09–1.31)
 Unknown 228 (2.3) 64 (2.1) 0.93 (0.69–1.27)
Alcohol consumption (units/week)d
 None 1771 (17.7) 483 (15.9) 1.00 (−)
 1–9 4722 (47.2) 1401 (46.2) 1.12 (0.99–1.26)
 10–20 1521 (15.2) 480 (15.8) 1.21 (1.04–1.41)
 ≥ 21 725 (7.3) 274 (9.0) 1.46 (1.20–1.78)
 Unknown 1261 (12.6) 395 (13.0) 1.15 (0.97–1.36)
Comorbiditiese
 Diabetes 1852 (18.5) 598 (19.7) 0.98 (0.87–1.10)
 IBD 124 (1.2) 40 (1.3) 1.04 (0.72–1.50)
 IBS 534 (5.3) 176 (5.8) 1.02 (0.85–1.22)
 Gout 765 (7.6) 250 (8.2) 1.10 (0.94–1.29)
 Hypertension 5626 (56.3) 1740 (57.4) 1.01 (0.93–1.11)
 Hypercholesterolemia 1655 (16.6) 484 (16.0) 0.96 (0.83–1.35)
 Upper GI disorders 2165 (21.6) 656 (21.6) 0.93 (0.84–1.03)
  1. BMI body mass index, CI confidence interval, CRC colorectal cancer, GI gastrointestinal, IBD inflammatory bowel disease, IBS irritable bowel syndrome, NSAIDS non-steroidal anti-inflammatory drugs, PCP primary care practitioner, RR rate ratio, u/w units per week
  2. aAdjusted by the matching variables (age, sex and year of index date) and number of PCP visits, smoking (any time before index date), insulin, NSAIDs, BMI (any time before index date) and oral steroids
  3. bIn the year before the index date
  4. cAny time before the index date taking the value recorded nearest to the index date
  5. dUnits per week = 10 ml (8 g) of pure ethanol
  6. eAny time before the index date except for GI disorders, which were ascertained anytime up to and including the start date. Reference group for all comorbidities was not having the respective condition
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