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We have found the article by Rungoe et al about ischaemic heart disease (IHD) in inflammatory bowel disease (IBD) patients to be quite interesting since there are not many studies on this topic and they are mainly retrospective.1
As reported by the Authors, the high incidence of IHD observed in patients with IBD during the first year is probably due to bias, as considered in the study by Yarur et al in which heart disease cases in the 12 months following the diagnosis of IBD were excluded.2
The same methodological problem appears in the years following the first diagnosis of IBD, because these patients are more closely studied compared to the control general population.
Rungoe's table 2 does not show the concordance between Crohn's Disease (CD) and Ulcerative Colitis (UC) patients and total IHD events, nor does it show statistical significance for CD and UC patients according to gender, but altogether the significance is p=0.03.
Even with all methodological limitations, Rungoe et al found a 5% global incidence of IHD in the general population and 4% in IBD patients.
We think it would be important to know if there are IHD cases in the general population in which IBD has been diagnosed after IHD and how these patients were classified.
As mentioned in the Discussion, the Incidence Rate Ratios (IRRs) were not adjusted according to some classic cardiovascular risk factors such as smoking and body mass index (BMI). The Authors also report that in the literature there are significant differences in smoking between CD and UC patients but no differential effects on IHD and therefore conclude that smoking is not an important risk factor.
However, the literature is controversial. In Yarur et al's study, the hazard ratio (HR) for smokers in the overall IBD patients was 0.712 vs 3.91 in the control group, while in Osterman et al's study the HR was 1.30 for UC and 1.44 for CD.2 ,3 Yarur et al's retrospective study was carried out in Florida with a follow-up of about 50 months in 356 IBD patients whereas Osterman's refers to a British database of 25 327 IBD patients with a follow-up of about 4.5 years.
The Authors report that in Scandinavian IBD patients, BMI decreases, citing an article by Geerling et al on only 69 IBD patients. Instead, Yarur et al and Osterman et al report that 45% and 30% of IBD patients, respectively, were either obese or overweight. The HR in Yarur's study for BMI≥30 was 0.530 and in Osterman's was 1.19 for overweight and 1.22 for obese patients.
On the contrary it could also be hypothesised that underweight is a risk factor due to vitamin deficiency which could manifest as hyperhomocystinemia.
As considered in Yarur et al's study and in agreement with the most recent literature, chronic renal insufficiency can also be considered a cardiovascular risk factor.
The use of contraceptive pills by women with IBD may also play a role in cardiovascular diseases.
Some articles published in Gut indicate that the standard mortality rate (SMR) in IBD patients due to cardiovascular disease is significantly lower than or equal to 1. Jess et al's study, carried out in Olmsted County, showed SMR was stratified according to use of immunosuppressants and other medications.4
It would be interesting to know the SMR of the groups studied by Rungoe et al, given the long follow-up of 13 years.
In conclusion, we think that prospective regional studies on this topic are needed, in which true inflammatory risk factors are taken into consideration as well as the classic cardiovascular risk factors.
Contributors PS and BS have contributed to this letter to the editor.
Competing interests None.
Provenance and peer review Not commissioned; internally peer reviewed.
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