Nonalcoholic Fatty Liver Disease of Two Ethnic Groups in Kuwait: Comparison of Prevalence and Risk FactorsBabusik P.a · Bilal M.b · Duris I.c
Departments of aInternal Medicine and bRadiology, Al-Rashid Hospital, Salmiya, Kuwait; cMedical Faculty of Comenius University, Bratislava, Slovakia Corresponding Author
Dr. Pavel Babusik, PhD
Namestie S. Moysesa 2A
SK–97401 Banska Bystrica (Slovakia)
Tel. +421 455201540, E-Mail firstname.lastname@example.org
Objectives: To assess the prevalence of nonalcoholic hepatic steatosis (nonalcoholic fatty liver disease, NAFLD) and the significance of some risk factors, such as obesity and glucose metabolism impairment, for two major ethnic groups of Kuwait: Arabs and South Asians. Subjects and Methods: 143 adults (Arab: n = 81; South Asian: n = 62) were enrolled in the study. Anthropometric measurements including body mass index (BMI), waist circumference (WC), hip circumference (HC) and waist-to-hip ratio were performed along with abdominal ultrasonography. The prevalence of liver steatosis was assessed; its relation to glucose metabolism impairment, obesity, age and gender was compared in the two ethnic groups. Results: Except for waist-to-hip ratio, the anthropometric parameters were higher in Arabs than South Asians. The respective parameters in Arabs and South Asians were: BMI: 30.9 ± 6.6 versus 27.0 ± 4.5, p < 0.001; WC: 101.5 ± 16.4 versus 94.0 ± 12.2, p = 0.002; HC: 106.6 ± 12.4 versus 99.2 ± 9.9, p < 0.001. Although Arabs were more obese, they did not exhibit a higher prevalence of steatosis (33.3 vs. 29.0%, p = 0.583). According to multivariate analysis, only gender (odds ratio 3.93, p = 0.005), glucose metabolism impairment (odds ratio 4.94, p = 0.003) and WC (odds ratio 4.75, p = 0.012) remained significantly associated with steatosis. Conclusion: No significant difference in NAFLD prevalence was found between Arabs and South Asians. Only gender, history of impaired glucose metabolism and abdominal obesity expressed by WC had an independent predictive value for developing liver steatosis.
© 2011 S. Karger AG, Basel
Liver steatosis is a common reaction of the liver to a variety of noxious stimuli and metabolic disturbances . Nonalcoholic fatty liver disease (NAFLD) is a very frequent form of chronic liver disease. Insulin resistance is recognized as a key promoter of NAFLD, reflected by any kind of glucose metabolism derailment – either type 2 diabetes, or any type of ‘prediabetes’ [2,3,4,5,6,7,8,9]. According to the published data, the strongest association of NAFLD is with central, not overall obesity [8,10], with intense links to metabolic syndrome. The pandemic of obesity appears to be a global problem, potentially leading from simple steatosis to necroinflammation and finally cirrhosis [2,3,4,5,6,7]. Patients with nonalcoholic steatohepatitis are at increased risk of premature death compared to the general population . In our previous study , we showed that the two main ethnic groups in Kuwait differed in the degree and the type of obesity and its impact on some metabolic risk factors of atherosclerosis. Therefore, the aim of this study was to clarify the significance of the differences for the prevalence of NAFLD.
The study was conducted from January 2007 to September 2008. 143 adult subjects, patients and clients of the Medical Clinic in Al Rashid Hospital, Kuwait were examined (Arabs: n = 81, South Asians: n = 62; age range: 18–64 years). The Arabs were from Kuwait, Saudi Arabia, United Arab Emirates, Jordan, Egypt and Syria. The South Asians were from India, Pakistan, Bangladesh or Sri Lanka. Ethnicity was established based on official documents showing country of origin and the person’s own confirmation of the data. Exclusion criteria were: presence of chronic liver disease other than NAFLD, chronic wasting conditions, diabetes type 1, history of jejunoileal bypass surgery, alcohol and/or substance abuse, chronic medication with potential hepatotoxicity, pregnancy, and conditions with fluid retention. Basic anthropometric measurements were done by a qualified and properly trained nurse. A nonstretchable tape was used for measurements of circumferences while the persons were in an upright position. The waist circumference (WC) was taken in the middle between the rib cage and the pelvis as the shortest circumference. The hip circumference (HC) was measured as the largest circumference at the level of greater trochanters. Body weight was checked by an electronic scale and the height was measured by a measuring rod attached to the same scale. Ultrasound examination of the upper abdomen was performed by a consultant radiologist skilled in the method and blind to the exact purpose of the examination. The criteria for steatosis were: increased parenchymal echogenicity of the liver compared to the kidney, vascular blurring, and deep attenuation of the ultrasound beam. Patients were either directly tested, or questioned regarding their previous history of diabetes, taking into account any derailment in glucose metabolism related to type 2 diabetes, including both impaired glucose tolerance and impaired fasting blood glucose.
All statistical analyses were performed using STATA (SE 8.2, StataCorp, College Station, Tex., USA). A p < 0.05 was used as the threshold for statistical significance. The χ2 test, χ2 test for linear trend or Fisher’s exact test were used to assess the association between two qualitative variables wherever appropriate. The 95% confidence intervals (CI) for the prevalence of steatosis were calculated using binomial distribution. Quantitative variables were compared between steatosis and nonsteatosis groups using an independent samples t test. Unadjusted odds ratios and their 95% CI were calculated separately for different risk factors in the prevalence of steatosis. Multiple logistic regression was used to estimate the risk of these factors in the prevalence of steatosis after controlling for confounding among them. The adjusted odds ratios and their 95% CI for associated factors were computed from the coefficients of the logistic regression model.
The parameters studied and characteristics of the two ethnic groups are shown in table 1. Previous history of glucose metabolism impairment, prevalence of steatosis and age were similar in both groups. Mean values of body mass index (BMI), WC, and HC were higher in Arabs than South Asians and the differences were statistically significant: BMI: 30.9 ± 6.6 versus 27.0 ± 4.5, p < 0.001; WC: 101.5 ± 16.4 versus 94.0 ± 12.2, p = 0.002; and HC 106.6 ± 12.4 versus 99.2 ± 9.9, p < 0.001. The waist-to-hip ratio (WHR) was similar in Arabs (0.95 ± 0.08) and South Asians (0.95 ± 0.06); the difference was not statistically significant (p = 0.863).
The prevalence of steatosis according to characteristics and anthropometric parameters is shown in table 2. Gender was highly predictive for the incidence of steatosis: the incidence was male: 49.1%; female: 19.8%. The difference was statistically significant (p < 0.001). There was no difference among the two ethnic groups in incidence rate: Arabs 33.3% and South Asians 29.0% (p = 0.683). Age was a predictor of incidence of steatosis, showing a linear trend (p = 0.025). We found highly significant associations between the presence of glucose metabolism impairment and steatosis (64.5% steatosis among diabetics vs. 22.3% in nondiabetics, p < 0.001), and all anthropometric measures of obesity (expressed as linear trends between tertiles with p < 0.001 for BMI, WC and WHR, and p = 0.003 for HC) and steatosis as well.
The prevalence of steatosis among Arabs and Asians based on their characteristics and the anthropometric measurements is shown in table 3. In Arabs, gender (p = 0.001), history of diabetes (p = 0.02) and all measures of obesity were significantly associated with steatosis (p = 0.001 for BMI and WC, p = 0.002 for HC and p = 0.004 for WHR). In South Asians, gender (p = 0.045), history of glucose metabolism impairment (p = 0.001), WC (p = 0.003) and WHR (p = 0.006) were significantly associated with steatosis. In both ethnic groups age was associated with steatosis (p = 0.016 and p = 0.046 for Arabs and South Asians, respectively).
The comparison of anthropometric measures in relation to steatosis is shown in table 4. Among Arabs, steatosis was associated with higher age (43.6 ± 13.5 years for steatosis vs. 35.1 ± 11.4 years without steatosis, p = 0.004), higher values of BMI (34.9 ± 5.9 vs. 28.9 ± 6.1, p < 0.001), WC (111.8 ± 15.9 vs. 96.3 ± 14.2, p < 0.001), HC (112.9 ± 13.0 vs. 103.5 ± 11.0, p = 0.001) and WHR (0.99 ± 0.07 vs. 0.93 ± 0.07, p = 0.001). These associations were statistically highly significant. Among South Asians, associations existed between steatosis and age (44.0 ± 12.0 vs. 38.3 ± 9.0, p = 0.046 for steatosis and nonsteatosis subgroup, respectively), WC (99.7 ± 10.1 vs. 91.7 ± 12.3, p = 0.017) and WHR (0.98 ± 0.05 vs. 0.93 ± 0.06, p = 0.013). Overall, age was significantly related to steatosis (43.8 ± 12.8 vs. 36.5 ± 10.5, p = 0.001) for the entire group studied. Significant correlations were present between steatosis and BMI, WC, WHR (p < 0.001) and HC (p = 0.001) as well.
Risk factors associated with steatosis by logistic regression analyses are given in table 5. After multivariate analysis only gender (odds ratio 3.93, p = 0.005), history of glucose metabolism impairment (odds ratio 4.94, p = 0.003) and WC (odds ratio 4.75, p = 0.012) remained statistically significantly associated with steatosis. No statistical significance was found between steatosis and age, ethnicity, BMI or WHR.
In our study, abdominal type obesity, defined through WC, was confirmed to be linked with steatosis in both ethnic groups, after adjustment for all other variables. Along with this association, we observed statistically significant differences between the two studied ethnicities: Arabs were more obese than South Asians based on BMI, WC and HC. In spite of that, the prevalence of glucose metabolism impairment and occurrence of steatosis in the two groups were similar. This finding is similar to the results of our former study : the same degree of obesity had more deleterious metabolic effects in South Asians than Arabs in Kuwait. Previous studies, too, confirmed that the South Asian ethnicity carries a higher genuine risk to exhibit adverse effects of obesity, in comparison with other ethnic groups, namely the Caucasians . The overall prevalence of liver steatosis in our study was 31.5%. We found a very strong correlation between steatosis and a history of glucose metabolism impairment. This confirms the fact that insulin resistance is a main risk factor for developing NAFLD [2,3,4,5,6,7,8,9,14]. The prevalence of NAFLD is not equal in different ethnicities [15,16,17,18,19,20,21]. The information about the different impact of obesity on developing NAFLD between Arabs and South Asians was lacking to date. We found some differences between our two studied ethnic groups: in Arabs, all studied anthropometric parameters were predictors of liver steatosis, contrary to the South Asians, where only WC and WHR were predictors of steatosis. In a multivariate analysis, however, WC remained the only anthropometric parameter related to steatosis, along with male gender and a history of impaired glucose metabolism. After adjustment for all other variables, the risk of steatosis for males was 4 times higher than for females. It is possible to speculate to what extent the differences were a result of specific lifestyle habits, with daily activities shifted to the late night hours (main meal consumed late at night), along with specific dietary habits both of which could lead to multiple metabolic impairment .
Our study confirmed that the prevalence of NAFLD is quite high in two major ethnic groups in Kuwait: Arabs and South Asians, and despite Arabs being more obese, the prevalence of steatosis did not differ from South Asians. The history of impaired glucose metabolism was a strong link to NAFLD. WC was an independent predictor of NAFLD in both ethnic groups, and NAFLD was much more common in the male population of Kuwait. The main limitation of our study is the small sample size and to some extent, the selective segment of the Kuwait population studied. Despite this, some careful extrapolations are possible to be done towards the whole Arab and South Asian population in Kuwait.
The authors wish to thank Ms. Jacinta F. Martiz for her technical help.
Dr. Pavel Babusik, PhD
Namestie S. Moysesa 2A
SK–97401 Banska Bystrica (Slovakia)
Tel. +421 455201540, E-Mail email@example.com
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