Table 2

Studies of smoking in CD where isolated colonic disease was separately identified

Author/refYearCountryNumber of cases CDNature of studyCurrent smoking OR/RR for CD phenotypeCurrent smoking* isolated colonic CD %Current smoking all CD%Current smoking CD excluding isolated colonic %Current smoking healthy controls %Current smoking UC %
Somerville et al731984UK82Case-controlRR for smoking and CD:
Small bowel only 3.5 (0.8–14.6)
Colon only 4.7 (1.4–16.1)
Small and large bowel 4.5 (1.8–11.5)
Holdstock et al741984UK150Consecutive outpatients25 (smokers with isolated colon CD had more relapses p=0.028)3552 8
Tobin et al751987UK137Case-controlRR for smoking at onset and CD:
Small bowel only 1.4 (0.5–4.0)
Ileum and ascending colon 6.0 (2.1–17.2)
Small bowel and rest of colon 3.9 (1.5–10.2)
Colon only 2.5 (0.8–7.3)
(controls for UC 40%)
Lindberg et al761992Sweden231Postal questionnaire (95% response)425153
Breuer-Katschinski et al771995Germany346Postal questionnaire
(82% response)
Russel et al781998Europe (20 centres, 13 countries)457Prospective consecutive cases35475916
Cosnes et al791999France622Consecutive outpatients544949
Cosnes et al802004France688 all colonicConsecutive outpatients6142
Aldhous et al812007UK (Scotland)408Retrospective outpatients334350
Hancock et al662008UK675DatabaseOR 1.64 (1.09–2.45) for never smokers with isolated colonic CD vs ileal or ileocolonic51 (ever)61 (ever)63
Chen et al622011USA628University databaseOR 1.69 (1.07–2.66) for any ileal involvement (L1+L3) vs colon only (L2)253738
Nunes et al822013Spain3224National registry263435
Chivese et al832015South Africa194Prospective consecutive casesRR 3.63 (1.32–9.98)
for ileocolonic vs colonic;
RR 3.54 (1.06–11.83)
for ileal vs colonic
  • *‘Current smoking’ variably either smoking at time of diagnosis or at time of sampling but excluding ‘ex-smoking’.

  • CD, Crohn's disease; RR, relative risk.