Non-alcoholic fatty liver disease in the South Asian Region: A systematic review and meta-analysis

Objectives We estimated the prevalence and effect sizes of associations for NAFLD, the commonest chronic liver disease worldwide, among South-Asian adults. Design We searched the PubMed database, using search terms “Prevalence of NAFLD (Non-Alcoholic Fatty Liver Disease)” AND “South Asia” AND South Asian countries (“Afghanistan”, “Bangladesh”, “Bhutan”, “India”, “Maldives”, “Nepal”, “Pakistan” and “Sri Lanka”). We included descriptive, epidemiological studies with satisfactory methodology, reporting the prevalence of NAFLD with a valid diagnostic method (ultrasound/CT imaging, biochemistry, histology). The quality of the studies was assessed using Joanna Briggs Institute Critical Appraisal Checklist for Prevalence Studies. Two authors screened and extracted data independently. A random-effects meta-analysis of prevalence and effect sizes of associations of NAFLD was performed. Gender, urban/rural setting, general population and individuals with metabolic diseases (MetD) stratified the analysis. Results Thirty-two articles were included in the systematic review, and 21 publications were included in the meta-analysis after quality assurance. The pooled overall prevalence of NAFLD in the general population was 25.2% [95%CI 20.3-30.5%] with high heterogeneity (k=9; Q=251.6, DF=8, P<0.0001, I 2 =96.8%). The prevalence was similar among men and women (Q=0.10, DF=1, P=0.746). The NAFLD prevalence in the rural communities were 26.0% (95%CI: 18.2–34.5%) and it was 26.6% (95%CI: 20.5-33.1%) in urban communities without significant differences in the prevalence (Q=0.01, DF=1, P= 0.916). The pooled overall prevalence of NAFLD in patients with MetD was 55.1% [95%CI 47.4-62.8%] with high heterogeneity (k=8; Q=53.8, DF=7, P<0.0001, I 2 =85.2%). The pooled overall prevalence of NAFLD in the non-obese population was 11.7% [95%CI 7.0-17.3%] (k=6; Q=170.1, DF=5, P<0.0001; I2=97.1%). The pooled prevalence of non-obese NAFLD in the NAFLD population was 43.4% [95%CI 28.1-59.4%] [k=6; Q=181.1; P<0.0001; I2=97.2%]. Meta-analysis of binary outcomes showed presence of NAFLD in South Asian population was associated with diabetes mellitus [RR-2.03 (1.56-2.63)], hypertension [RR-1.37 (1.03-1.84)], dyslipidaemia [RR-1.68 (1.51-1.88)], general obesity [RR-2.56 (1.86-3.51)], central obesity [RR-2.51 (1.69-3.72)] and metabolic syndrome [RR-2.86 (1.79-4.57)]. Gender was not associated with NAFLD. Conclusions The overall prevalence of NAFLD among adults in South Asia is high, especially those with metabolic abnormalities, and a considerable proportion are non-obese. In the South Asian population, NAFLD was associated with MetD. Strengths and limitations There has been no meta-analysis of epidemiological data on NAFLD from the South Asian region. Therefore, we estimated the overall prevalence and effect sizes of risk factors for NAFLD among South-Asian adults. We carried out an extensive quality assessment of the studies and included only studies with satisfactory methodological quality in the final analysis to ensure the validity of the results. In the present study, the prevalence of NAFLD among adults in the South Asian region seems compatible with the global average, and the prevalence was especially in individuals with metabolic abnormalities. This study was limited to available data among adults, excluding the paediatric and adolescent population.