The prevalence and disease course of autoimmune liver diseases in Greenland

Autoimmune liver diseases are rare serious diseases causing chronic inflammation and fibrosis in the liver parenchyma and bile ducts. Yet, the prevalence and burden of autoimmune liver diseases are largely unexplored in Arctic native populations. We investigated the prevalence and management of autoimmune liver diseases in Greenland using nationwide cross-sectional register data and subsequent medical chart reviews validating diagnoses and extracting liver histology examinations and medical treatments. The overall prevalence of autoimmune liver diseases in Greenland was 24.6 per 100,000 (95% CI: 14.7-41.3). This was based on 7 patients with autoimmune hepatitis (AIH) (12.3 per 100,000), 3 patients with primary biliary cholangitis (PBC) (5.3 per 100,000), 4 patients with AIH/PBC overlap disease (7.0 per 100,000), and no patients with primary sclerosing cholangitis. All diagnoses were confirmed by liver histology examinations. Medical treatments adhered to internal recommendations and induced complete remission in most patients with AIH, and complete or partial remission in 1 patient with PBC and 3 patients with AIH/PBC overlap disease. One patient had established cirrhosis at the time of diagnosis, while 2 patients progressed to cirrhosis. In conclusion, the prevalence of autoimmune liver diseases was lower in Greenland than in Scandinavia and among Alaska Inuit.

Signs of non-alcoholic fatty liver disease in indigenous Arctic populations - a systematic review

INTRODUCTION

The increasing prevalence of obesity and type 2 diabetes mellitus has become a global healthcare concern spreading to indigenous Arctic populations. As non-alcoholic fatty liver disease (NAFLD) is strongly associated with the metabolic syndrome, it has become a leading cause of chronic liver disease. However, data are sparse on the prevalence of NAFLD in indigenous Arctic populations who may have a different risk profile for diabetes complications.

METHODS

We conducted a systematic review to estimate the prevalence of NAFLD or signs of NAFLD in indigenous Arctic people inhabiting Greenland, Alaska, Canadian territories and Eastern Russia. Also, we wanted to discuss how Arctic research in metabolic disease such as NAFLD may move forward.

RESULTS

Through the pre-specified search of Ovid MEDLINE and Embase, 3,070 unique references were identified and six studies including 5,487 persons qualified for data extraction. The prevalence of NAFLD or signs of NAFLD varied between 21% and 65%. The risk of bias was considerable particularly due to the inclusion of small and heterogeneous studies.

CONCLUSION

Only limited published research exists on NAFLD in indigenous Arctic populations. This review reports that the prevalence of NAFLD or signs of NAFLD in the indigenous Arctic populations residing in Arctic Regions may be similar to the global level, emphasising the need for further health research in indigenous Arctic populations.

Non-alcoholic fatty liver disease in patients with type 2 diabetes in Greenland: a register-based cross-sectional study

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide due to its close association to the metabolic syndrome of type 2 diabetes mellitus (T2DM), obesity and insulin resistance. However, the prevalence and severity of NAFLD in Greenland remain unexplored. We aimed to estimate the prevalence of liver steatosis and fibrosis among Greenlanders and Danes with T2DM living in Greenland using biochemical surrogate markers. We included 1409 Greenlanders and 182 Danes with T2DM in this register-based cross-sectional study. Greenlanders had higher BMI and plasma lipid levels and lower HbA1c levels compared with Danes (p<0.05). Their median alanine aminotransferase (ALAT) levels were similar. However, more Greenlanders had elevated ALAT levels (20.5% vs. 11.5%, p<0.05). Greenlanders had lower FIB-4 scores than Danes, 0.91 (IQR: 0.66–1.27) vs. 0.97 (IQR: 0.78–1.34), without difference in FIB-4 score categories (p=0.27). The prevalence of advanced fibrosis was low in both populations (1.7–2.6%). In conclusion, Greenlanders with T2DM had better glycaemic control despite higher BMI and plasma lipids. A larger proportion of Greenlanders had elevated plasma ALAT levels, while FIB-4 scores were lower than Danes. These findings suggest that Greenlanders with T2DM may be less likely to develop liver complications than Danes with T2DM in Greenland.

Risk of hepatitis B when migrating from low to high endemic areas

Prevalence of hepatitis B virus (HBV) infections varies markedly with geography and is endemic in the Arctic. Travel and migration have increased markedly while the influence of migration to high endemic areas remains unknown. We surveyed subjects migrating from an area with a low prevalence of chronic HBV infection (Denmark, 0.01%) to an endemic HBV area (West- and East Greenland, 3% and 29%) in order to describe the prevalence of HBV exposure among migrants. We included 198 Caucasian Danes that had migrated to Greenland and repeated the cross-sectional investigation after 10 years. We performed thorough serological testing for HBV. None had ongoing HBV infection. Migrants to East Greenland were more frequently exposed to HBV than those in West Greenland (34.3% vs 10.3%; p < 0.01). This difference was reduced at 10-year follow-up (8.1% vs 5.7%; ns) and the overall number of participants with past HBV infection decreased over the 10-year period from 19.4% to 6.9% (p = 0.02). In conclusion, migration from very low prevalence to endemic HBV areas associated with a markedly increased risk of exposure to HBV. Lack of vaccination among migrants from Denmark to Greenland was frequent and it poses a continuing risk. All who migrate from low to high endemic HBV areas should be vaccinated.

Abbreviations

HBV: Hepatitis B virus; HBV-DNA: Hepatitis B virus deoxyribonucleic acid; HBsAg: Hepatitis B surface antigen; Anti-HBs: Antibodies against hepatitis B surface antigen; Anti-HBc: Antibodies against hepatitis B core antigen; BMI: Body mass index

Liver biochemistry and associations with alcohol intake, hepatitis B virus infection and Inuit ethnicity: a population-based comparative epidemiological survey in Greenland and Denmark

Background

Hepatitis B virus (HBV) infection is common in Arctic populations and high alcohol intake has been associated with an increased risk of a number of diseases. Yet, a description of the influence of alcohol intake in persons with HBV infection on liver biochemistry is lacking.

Objective

We aimed to describe the association between reported alcohol intake and liver biochemistry taking into account also HBV infection, ethnicity, Inuit diet, body mass index (BMI), gender and age in an Arctic population.

Design and methods

Population-based investigation of Inuit (n=441) and non-Inuit (94) in Greenland and Inuit living in Denmark (n=136). Participants filled in a questionnaire on alcohol intake and other life style factors. Blood samples were tested for aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), bilirubin, albumin, hepatitis B surface antigen, hepatitis B surface antibody and hepatitis B core antibody. We also performed physical examinations.

Results

Participation rate was 95% in Greenland and 52% in Denmark. An alcohol intake above the recommended level was reported by 12.9% of non-Inuit in Greenland, 9.1% of Inuit in East Greenland, 6.1% of Inuit migrants and 3.4% of Inuit in the capital of Greenland (p=0.035). Alcohol intake was associated with AST (p<0.001) and GGT (p=0.001), and HBV infection was associated with ALP (p=0.001) but not with AST, GGT, bilirubin or albumin in the adjusted analysis. Inuit had higher AST (p<0.001), GGT (p<0.001) and ALP (p=0.001) values than non-Inuit after adjustment for alcohol, diet, BMI and HBV exposure. Ethnic origin modified the association between alcohol and AST, while HBV infection did not modify the associations between alcohol and liver biochemistry.

Conclusions

Non-Inuit in Greenland reported a higher alcohol intake than Inuit. Ethnic origin was more markedly associated with liver biochemistry than was alcohol intake, and Greenlandic ethnicity modified the effect of alcohol intake on AST. HBV infection was slightly associated with ALP but not with other liver biochemistry parameters.

Hepatitis B among Inuit: A review with focus on Greenland Inuit

Hepatitis B virus (HBV) infection is a disease with a highly variable course. Chronic HBV infection may cause end-stage liver disease including cirrhosis and hepatocellular carcinoma, which is the 3^rd most common cause of cancer related death due to the poor prognosis. The prevalence of HBV infection is low in many countries. Still, it remains important due to the potential consequences of the disease. HBV is endemic in the Arctic with serologic markers of chronic HBV infection in up to 29% of the population in some areas in Greenland. Interestingly, Inuit populations rarely show signs of liver disease despite the fact that around half of all Inuit has been exposed to HBV and around 8% of Inuit are chronically infected with HBV. These findings have been consistent in surveys conducted for more than four decades among Arctic Inuit. We thus review HBV infection in the Arctic with focus on Greenland Inuit and compared with Inuit in Canada, Alaska and Siberia. The aspects described include epidemiology and monitoring of the disease, as well as treatment and the risk of liver cancer.

Forty-five year trends in overweight and obesity in an indigenous arctic Inuit Society in transition and spatiotemporal trends

OBJECTIVES

Overweight and obesity associate with increased morbidity and premature death. Westernization of societies heralds rising obesity rates. A steep increase in body mass index (BMI) and overweight in Greenland from 1963 to 1998 led us to follow-up on height, weight, BMI, and rates of overweight among populations in Greenland and assess time trends between different stages of transition.

METHODS

BMI was calculated from height and weight measured on Inuit and non-Inuit aged 50 through 69 years surveyed in 1963, 1998, and 2008 in Ammassalik district in East Greenland and in 1998 and 2008 in the capital Nuuk in West Greenland.

RESULTS

A total of 1,186 were surveyed in 1963 (52 men/63 women), 1998 (309/226), and 2008 (297/239). BMI increased with time (P < 0.001; 1963/1998/2008 23.3/24.3/26.2 kg/m(2) ). In addition, BMI increased with urbanization in Inuit men (P = 0.001; settlements/town/city, in 1998, 23.9/24.9/25.5 kg/m(2) ; in 2008, 25.0/26.0/27.0 kg/m(2) ) while not in Inuit women (P = 0.18). The number of overweight Inuit (BMI >27 kg/m(2) ) increased with time in men (4.0/25.6/33.2% in 1963/1998/2008, P = 0.001) and in women (13.6/30.7/37.3%, P = 0.001). BMI was above 30 kg/m(2) in 2.0/10.8/17.5% of all Inuit men in 1963/1998/2008 (P = 0.003) and in 8.3%/23.0/24.5% of all Inuit women (P = 0.02) respectively.

CONCLUSIONS

Overweight and obesity rates rise with time and with societal transition in Greenland. Settlements and town are catching up with the city where the rate of increase is diminishing, although there were gender differences.

Raised BMI cut-off for overweight in Greenland Inuit--a review

Background

Obesity is associated with increased morbidity and premature death. Obesity rates have increased worldwide and the WHO recommends monitoring. A steep rise in body mass index (BMI), a measure of adiposity, was detected in Greenland from 1963 to 1998. Interestingly, the BMI starting point was in the overweight range. This is not conceivable in a disease-free, physically active, pre-western hunter population.

Objective

This led us to reconsider the cut-off point for overweight among Inuit in Greenland.

Design and findings

We found 3 different approaches to defining the cut-off point of high BMI in Inuit. First, the contribution to the height by the torso compared to the legs is relatively high. This causes relatively more kilograms per centimetre of height that increases the BMI by approximately 10% compared to Caucasian whites. Second, defining the cut-off by the upper 90-percentile of BMI from height and weight in healthy young Inuit surveyed in 1963 estimated the cut-off point to be around 10% higher compared to Caucasians. Third, if similar LDL-cholesterol and triglycerides are assumed for a certain BMI in Caucasians, the corresponding BMI in Inuit in both Greenland and Canada is around 10% higher. However, genetic admixture of Greenland Inuit and Caucasian Danes will influence this difference and hamper a clear distinction with time.

Conclusion

Defining overweight according to the WHO cut-off of a BMI above 25 kg/m² in Greenland Inuit may overestimate the number of individuals with elevated BMI.

Population-based comparative epidemiological survey of hepatitis B, D, and C among Inuit migrated to Denmark and in high endemic Greenland

OBJECTIVE

Infection with hepatitis B virus (HBV) is endemic among Arctic populations where it may have a benign course. However, the relation of HBV to migration to low endemic areas is unknown, as it is for hepatitis D and C, and details on the influence of delta virus at a population level are lacking.

MATERIAL AND METHODS

Population-based investigation of Greenlanders living in Denmark (n = 136) and in Greenland (n = 441). We tested for HBsAg, anti-HBs, anti-HBc, HBeAg, anti-HBe, HBV-DNA, HBV genotypes, anti-HDV, HDV-RNA, anti-HCV, HCV-Elisa test, HCV-RNA, aspartate aminotransferase, gamma-glutamyl transferase, bilirubin, and albumin, and performed a physical examination.

RESULTS

Participation rate was 52/95% in Denmark/Greenland. Half of participants in Denmark had lived more than half of their lives in Denmark, and 54.5% had been exposed to HBV. This was similar to 53% among Greenlanders living in West Greenland (p = 0.76). HBsAg was positive in 4.4% of Greenlanders in Denmark (n = 6), who all were anti-HBe positive and had low viral load. Serological signs of HBV infection associated with having both parents born in Greenland (p = 0.007) and with IV drug use (p = 0.03). We found serological signs of HDV exposure among participants in Denmark/Greenland in 0.7/1.1% (n = 1/5) and HCV exposure in 1.5/0.0% (n = 2/0). Liver biochemistry was elevated in Greenlanders exposed to HDV.

CONCLUSIONS

Hepatitis B, D, and C occurrences among Greenlanders in Denmark mirrored that of Greenland. Importantly, previously undetected exposure to delta virus associated with elevated liver biochemistry, and the introduction of delta virus is a liability to Greenlanders and to Greenland.