Association between smoking and non-alcoholic fatty liver disease: A systematic review and meta-analysis - PubMed (original) (raw)
Association between smoking and non-alcoholic fatty liver disease: A systematic review and meta-analysis
Arash Akhavan Rezayat et al. SAGE Open Med. 2018.
Abstract
Background/aims: Non-alcoholic fatty liver disease is one of the most common chronic liver diseases. Some risk factors are known to influence the development of non-alcoholic fatty liver disease, but the effect of tobacco smoking on the progression of non-alcoholic fatty liver disease is controversial. The main goal of this systematic review and meta-analysis is to investigate the association between smoking and non-alcoholic fatty liver disease.
Method: Electronic databases (PubMed, Scopus, and ISI Web of Science) were searched to find published articles on non-alcoholic fatty liver disease and smoking until December 2016. All relevant studies were screened by inclusion and exclusion criteria and compatible studies were chosen. The Newcastle-Ottawa Scale was used to assess the methodological quality of eligible articles. Subsequently, information was gathered based on the following: author, publication year, keywords, country, inclusion and exclusion criteria, main results, study design, conclusion, and confounder variables (age, body mass index, gender, ethnicity, and diabetes). Finally, analyses were performed using Comprehensive Meta-Analysis Software.
Results: Data were extracted from 20 observational studies (9 cross-sectional, 6 case-control, 4 cohort studies, and 1 retrospective cohort study). A significant association was observed between smoking and non-alcoholic fatty liver disease with a pooled odds ratio of 1.110 (95% confidence interval, 1.028-1.199), p-value = 0.008. The statistical heterogeneity was medium with an I2 of 40.012%, p-heterogeneity = 0.074. Also there was a significant relation between non-alcoholic fatty liver disease and passive smoking with a pooled odds ratio of 1.380 (95% confidence interval, 1.199-1.588; p-value = 0.001; I2 = 59.41; p-heterogeneity = 0.117).
Conclusion: Our meta-analysis demonstrated that smoking is significantly associated with non-alcoholic fatty liver disease. Further prospective studies exploring the underlying mechanisms of this association should be pursued. Also passive smoking increases the risk of non-alcoholic fatty liver disease about 1.38-fold. The effects of smoking cigarettes on active smokers (current smoker, former smoker, and total smoker) are less than passive smokers. Further studies are needed to compare the of effects of passive and active smoking on non-alcoholic fatty liver disease.
Keywords: Smoking; fatty liver; liver; non-alcoholic liver disease.
Conflict of interest statement
Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Figures
Figure 1.
Flow diagram of included and excluded studies.
Figure 2.
(a) Forest plot of the included studies assessing the association between smoking and non-alcoholic fatty liver disease; a diamond data marker represents the overall OR, 95% CI, and relative weight for the outcome of interest. (b) Funnel plot of the included studies represents the tau score = −0.075, z-value for tau = 0.34, and p-value (two-tailed) = 0.73 in Begg and Mazumdar rank correlation test that show publication bias does not exist in this study.
Figure 3.
Subgroup analysis assessing (a) current and (b) former smokers for the risk of non-alcoholic fatty liver disease in included studies; a diamond data marker represents the overall OR and 95% CI for the outcome of interest.
Figure 4.
Subgroup analysis assessing passive smokers for the risk of non-alcoholic fatty liver disease in included studies; a diamond data marker represents the overall OR and 95% CI for the outcome of interest.
Figure 5.
Analysis assessing according to study design ((a) cross-sectional studies, (b) case-control studies, and (c) cohort studies) for the risk of non-alcoholic fatty liver disease in included studies; a diamond data marker represents the overall OR and 95% CI for the outcome of interest.
References
- Ludwig J, Viggiano TR, Mcgill DB, et al. Nonalcoholic steatohepatitis: Mayo Clinic experiences with a hitherto unnamed disease. Mayo Clin Proc 1980; 55: 434–438. - PubMed
- Clark JM, Brancati FL, Diehl AM. The prevalence and etiology of elevated aminotransferase levels in the United States. Am J Gastroenterol 2003; 98: 960–967. - PubMed
- Chen S, Teoh NC, Chitturi S, et al. Coffee and non-alcoholic fatty liver disease: brewing evidence for hepatoprotection? J Gastroen Hepatol 2014; 29: 435–441. - PubMed
- Kissebah AH, Krakower GR. Regional adiposity and morbidity. Physiol Rev 1994; 74: 761–811. - PubMed
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