Risk Factors for Inflammatory Bowel Disease in the General Population

L. A. García Rodríguez; A. González-Pérez; S. Johansson; M.-A. Wallander


Aliment Pharmacol Ther. 2005;22(4):309-315. 

In This Article


The resulting overall incidence of IBD was 21 per 100 000 py in our 20–84 year old source population. The corresponding incidences for UC, CD, and indeterminate colitis were 11, 8, and 2 cases per 100 000 py, respectively. Figure 1 shows incidence rates of UC, and CD stratified by age groups. Incidence of CD was highest in the youngest age group. Incidence of UC varied with age and showed several peaks in patients in the third, and fifth decade of life as well as among those over 70 years of age. Incidence rate of CD was similar between sexes whereas incidence rate of UC was higher in males (12 per 100 000 py) than in females (8 per 100 000 py).

Incidence Rate of UC and CD Stratified by Age

Table 1 shows the estimates of the association between selected prior comorbidity and the estimates of OR for UC and CD. Diabetes was associated with an increased OR of UC (2.09, 95% CI:1.20–3.66) but not CD. On the other hand, rheumatoid arthritis was more markedly associated with CD (OR:4.38, 95% CI:2.01–9.51). Patients diagnosed with IBS more than 1 year before the index date experienced an increased risk of both UC and CD.

We found that patients with a recorded diagnosis of depression for the first time in the 2 years prior to the index date presented a small increased risk of UC (OR:1.39, 95% CI: 0.71–2.71) no different from the one when the diagnosis had been made two or more years prior (OR:1.37, 95% CI: 0.90–2.08). Patients diagnosed with anxiety in the 2 years prior to the index date and two or more years before the index date presented ORs for UC of 0.79 (95% CI:0.31–1.98) and 1.50 (95% CI:0.97–2.30), respectively.

Current smokers had a reduced risk of UC (OR:0.61, 95% CI:0.42–0.89) and an increased risk of CD (OR:1.74, 95% CI:1.22–2.48). The reduced risk of UC among smokers transformed into a slightly elevated risk of UC after smoking cessation. Interestingly, this increased risk of UC among ex-smokers was seen only in the first year after smoking cessation (OR:2.51, 95% CI:1.24–5.09) and thereafter (more than 1 year) returned close to the background risk (OR:1.19, 95% CI:0.72–1.99). The corresponding estimates of CD among former smokers were 2.01 (95% CI:0.71–5.66) and 1.68 (95% CI:0.92–3.07), respectively.

Patients who underwent appendectomy presented a decreased risk of developing UC (OR:0.37, 95% CI:0.14–1.00). The association was very similar when appendectomy 5 years or more before index date was considered (OR:0.42, 95% CI:0.16–1.15). Appendectomy was not associated with the subsequent occurrence of CD.

As shown in Table 2 , neither aspirin (OR:0.76, 95% CI:0.44–1.29) nor NA-NSAIDs (OR:1.38, 95% CI:0.96–2.00) were significantly associated with the risk of IBD. Current use of paracetamol was associated with a twofold increased risk of IBD (2.02, 95% CI:1.43–2.85). When we examined the effect of paracetamol according to treatment duration, we observed that the increased risk was concentrated during the first month after starting paracetamol (OR:3.32, 95% CI:2.15–5.14) and then decreased gradually over time. Chronic users of paracetamol for longer than 1 year experienced no increased risk of IBD (OR:0.90, 95% CI:0.45–1.79). Results were similar when analysing separately UC and CD.

Women who were currently using OCs were at increased risk of developing both UC (OR:1.58, 95% CI:0.71–3.52) and CD (OR:1.94, 95% CI:0.85–4.45). These risks were especially elevated with long-term use of OCs ( Table 3 ). While current users of HRT had a twofold increased OR of developing CD (OR:2.08, 95% CI:1.10–4.38), their risk of UC was similar to those women who never used HRT (OR:0.96, 95% CI:0.41–2.25). Increasing duration of HRT use was associated with a greater risk of CD ( Table 3 ).


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