Published online Oct 7, 2019. doi: 10.3748/wjg.v25.i37.5676
Peer-review started: June 13, 2019
First decision: July 21, 2019
Revised: July 30, 2019
Accepted: August 19, 2019
Article in press: August 19, 2019
Published online: October 7, 2019
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. It can progress from simple hepatic steatosis to nonalcoholic steatohepatitis, liver fibrosis (LF), cirrhosis and hepatocellular carcinoma. NAFLD is a frequently reported condition in patients with inflammatory bowel disease (IBD).
The underlining causes and predisposing factors to NAFLD among IBD patients remain poorly investigated. Both intestinal inflammation and metabolic factors are believed to contribute to the pathogenesis of IBD-associated NAFLD.
The aim of the study was to evaluate the prevalence of steatosis and LF in a cohort of IBD patients and the identification of metabolic- and IBD-related risk factors for NAFLD and LF. The results of the present project could provide new diagnostic tools for the estimation of individual risk of evolution allowing to set up new tools for prevention, diagnosis and prognosis with a personalized approach to the patient.
We conduct an observational study enrolling consecutive IBD patients in regular follow-up. At the time of enrollment each patient was evaluated through medical examination, complete blood tests and a nutritional evaluation where were obtained anthropometric parameters [body mass index (BMI), waist circumference, visceral fat, body fat, lean body mass] and, by asking the patients to describe the foods and drinks consumed in the previous 24 h (24-h dietary recall), we collected the usual dietary intake. The same day they underwent abdominal ultrasound to establish the presence and severity of NAFLD and a transient elastography to evaluate LF.
Of 178 consecutive IBD patients were enrolled in our study (95 ulcerative colitis and 83 Crohn’s disease). The prevalence of NAFLD was found in 72 patients (40.4 %). Comparison between patients with and without NAFLD showed no significant differences in terms of IBD severity, disease duration, location/extension, use of IBD-related medications (i.e., steroids, anti-TNFs, and immunomodulators) and surgery. NAFLD was significantly associated with the presence of metabolic syndrome (MetS, OR: 4.13, P = 0.001) and obesity defined by BMI (OR: 9.21, P = 0.0002), waist circumference (OR: 2.69, P = 0.001) and visceral fat (OR: 3.82, P = 0.001). IBD patients with NAFLD showed higher caloric intake and lipid consumption than those without NAFLD, regardless disease activity. At the multivariate analysis, male sex, advanced age and high lipid consumption were independent risk factors for the development of NAFLD. An increased liver stiffness was detected in 21 patients (16%) and the presence of MetS was the only relevant factor associated to LF (OR: 3.40, P = 0.01).
Our study confirms the epidemiological burden of NAFLD in IBD. It failed to demonstrate the association between IBD-related factors including medications (steroids, thiopurine, and TNF inhibitors) and the risk to develop NALFD, while confirming as risk factors the same of the general population, including obesity, overweight, unbalanced high lipidic diet, MetS and advanced age. The recent improvements in IBD therapy induce patients with long periods of well-being, bringing them to increase food intake and unbalanced diet. Furthmore, patients with IBD could tend to associate symptoms such as abdominal distention and diarrhea to fiber and complex carbohydrates intake, thus limiting their daily consumption, preferring proteic and fat foods. This emphasizes the importance of the dietary habits and the metabolic profile rather than the intestinal inflammation in the stratification risk for liver steatosis. It appears necessary that IBD care should also include nutritional and metabolic interventions, with the objective to maintain the intestinal welfare of patients, avoiding the development of metabolic complications associated with an unbalanced diet. A pratical approach could be to promote a healthy life style and encourage the use of complex carbohydrates together with fruit and vegetables and to reduce the intake of fats and proteins.
There are currently no recommended routine screening strategies for NAFLD in patients with IBD. However, our results suggest that IBD patients should be screened for NAFLD-associated risk factors in order to prevent the development of liver disease. Considering the fearsome consequence of NAFLD, data demonstrates that IBD care should not be limited to intestinal therapy, but should include metabolic interventions, by promoting healthy life-style and a correct dietary intake. However further perspective studies are still necessary to determinate the impact of the natural history of IBD with the presence of NAFLD and their evolution.