Determining the Risk of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis

By Christopher R. Selinsky, OMSII, Frank L. Schwartz, MD, FACE, Grace D. Brannan, PhD, and Jay H. Shubrook, DO, FACOFP

ABSTRACT: The objective of this paper is to determine the prevalence of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) in patients presenting to an endocrinology center in Appalachian Ohio. This retrospective study reviewed charts of 2,601 patients. Data recorded from the charts included: age, gender, weight (kg), height (cm), body mass index (kg/m2); diagnosis of diabetes mellitus type 2 (DM2), pre-diabetes, metabolic syndrome (MS), polycystic ovarian syndrome (PCOS), levels of liver transaminases and alkaline phosphatase: and, one of the following diagnoses: no diagnosis of NASH; presumed NAFLD /NASH; or biopsy confirmed diagnosis of NASH.

The study population consisted of 2,338 subjects. Females comprised 70.9 percent of the population. The prevalence of DM2, pre-diabetes, MS, and PCOS were 28.4 percent, 5.2 percent, 19.6 percent, and 3.9 percent, respectively. The prevalence of biopsy confirmed NASH was 1.3 percent, and prevalence of confirmed NASH combined with the presumed NAFLD/NASH was 24.9 percent.

The mean age (51 years), BMI (37.3 kg/m2), ALT (40 IU/L), and AST (29.5 IU/L) were significantly higher in the presumed NAFLD/NASH group than the non-NASH group. All measured co-morbid conditions except pre-diabetes were statistically significantly higher (p<0.01) in the NAFLD/NASH group than the non-NASH group.
The prevalence of NAFLD/NASH (25 percent) in an endocrinology practice population in Appalachian Ohio is high. This finding correlates with the high level of co-morbid conditions associated with the development of NASH in the region as well. Because of increasing prevalence, general asymptomatic presentation of NAFLD/NASH, problems with current diagnostic methods, and lack of treatment options, NAFLD/NASH is an under-recognized emerging public health concern that warrants further research.

Background
Nonalcoholic fatty liver disease (NAFLD) encompasses a wide range of diseases with varying hepatic damage. The spectrum ranges from benign simple steatosis to nonalcoholic steatohepatitis (NASH) with clinical consequences such as cirrhosis and hepatocellular carcinoma.1, 2

NAFLD is defined by 5 percent to 10 percent hepatic lipid accumulation by weight. NAFLD diagnosis requires no history of alcohol abuse, current alcohol consumption of less than 20 grams/day (i.e. approximately 2 standard drinks), and the exclusion of viral hepatitis.3 The clinical importance of NASH is its potential to progress to more serious complications such as cirrhosis and hepatocellular carcinoma.4

The current gold standard for diagnosis of NAFLD is exclusion of the above conditions/risk factors accompanied by a liver biopsy that demonstrates one or more of the following: hepatic macrosteatosis, mild inflammation, and hepatocellular ballooning.5 However, this is an invasive procedure and is currently underutilized. Many clinicians make a presumed diagnosis of NAFLD/NASH based on exclusion of risk factors and the presence of elevated liver transaminases and/or fatty liver found on imaging studies. This, although perhaps more practical, has not been measured for its sensitivity or specificity.

Ludwig et al6 were pioneers in NAFLD research and coined the term NASH in 1980. Since that time, NAFLD/NASH has been on the rise in the general population, and current research suggests that the prevalance is as high as 31 percent and 33.6 percent, respectively.7, 8

Furthermore, NAFLD is highly associated with co-morbid conditions such as obesity, metabolic syndrome (MS), polycystic ovarian syndrome (PCOS) and diabetes mellitus type 2 (DM2). 1,9,10,11 Currently 66 percent of adults in the United States are overweight (BMI>25 kg/m2), and an estimated 25 percent are obese (BMI≥30 kg/m2). This is expected to increase to nearly 45 percent by 2015.12 In another study, the prevalence of NAFLD in a severely obese (BMI≥40 kg/m2) population was found to be 36 percent.13

Nearly a quarter of the United States population 20 years old or older have metabolic syndrome.14 This is of growing concern because NAFLD/NASH is currently thought of as the hepatic manifestation of MS.11,15 Among those with MS the prevalence of NAFLD is nearly 50 percent.16 For those individuals who are obese or have DM2 the prevalence increases almost 2.5 fold.17 The incidence of NAFLD has been reported as high as 55 percent in PCOS patients.18

It is estimated that 75 percent of DM2 patients are affected by NAFLD.19 A significantly lower number of the general population, approximately 3 percent, is known to have NASH defined by a liver biopsy.20 In light of the dramatic increase in those diseases associated with NAFLD/NASH one would expect the prevalence of this disease to rise sharply as well.

Recent data suggests that some of the risk factors for NAFLD/NASH are significantly higher in this region (Appalachian Ohio) as compared to national averages. This data demonstrates the co-morbid condition of greatest significance is DM2 at 57 percent above the national average. Furthermore, obesity and hypertriglyceridemia are also above the national average.(21) One can infer from the data that the prevalence of NAFLD is, or will be, increasing across the Appalachian region.
Having acknowledged that the prevalence of risk factors for developing NAFLD/NASH is increasing at alarmingly high rates in Appalachian Ohio and across the United States, and the prevalence of NAFLD and NASH in this region is unknown, our aim for this study was to determine the prevalence of NAFLD/NASH in an endocrinology center serving Appalachian Ohio and to compare this to national prevalence data.

Methodology
This study used a retrospective chart review of 2,601 patients. Variables included: age, gender, weight (kg), height (cm), body mass index or BMI (kg/m2), diagnosis of DM2, diagnosis of pre-diabetes mellitus (impaired glucose tolerance), diagnosis of MS, diagnosis of PCOS, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma glutamyl transpeptidase (GGT), liver biopsy and description, liver imaging studies and descriptions, hepatotoxic drug consumption, alcohol consumption, evidence of viral hepatitis. Finally, all participants were placed into one of the following categories: no diagnosis of NAFLD/NASH, presumed NAFLD/NASH or biopsied confirmed NASH.

DM2 was defined as having a fasting blood glucose of ≥126 mg/dL and pre-diabetes mellitus by impaired fasting glucose (>100 mg /dl) or impaired glucose tolerance defined as a random blood glucose greater than 140 mg/dL and < 200 mg/dL. Metabolic syndrome was defined by parameters set by ATP III guidelines. The parameters for presumed NAFLD/ NASH included a diagnosis of metabolic syndrome, diagnosis of PCOS, diagnosis of DM2 with a BMI≥40 kg/m2, or any combination of these parameters.

Subjects were excluded from the study if they had previous or current alcohol consumption of greater than 20g/day, were taking hepatotoxic drugs (glucocorticoids, calcium-channel blockers, amiodarone, methotrexate, or antiviral agents), or had evidence of viral hepatitis.
The statistical analysis was completed using SPSS Version 15.0 (SPSS, Chicago). Descriptive statistics including frequency and means were generated. For nominal variables, a Chi-square non-parametric test was used to determine statistical significance. For continuous variables such as BMI, an independent t-test was performed. Statistical significance was set at α= 0.05.

This study was approved by the Ohio University Institutional Review Board.

Results
The population studied consisted of 2,601 subjects with 263 excluded because of one or more of the following: alcohol consumption of >20g/day, hepatotoxic drug consumption, or evidence of viral hepatitis. Therefore the number of subjects that met the inclusion criteria totaled 2,338. The population consisted of 1,657 (70.9 percent) females and 680 (29.1 percent) males with one subject missing gender identification. The prevalence of liver biopsy diagnosed NASH was 1.3 percent. Combined presumed NAFLD/ NASH was 24.9 percent. The mean age of the population was 48.9 years and mean BMI was 30.6 kg/m2. Results for the liver function tests ALT, AST, and ALP were 32.4 IU/L, 26.3 IU/L, and 87 IU/L, respectively.

As shown below in Table 1, the NAFLD/NASH group exhibited significantly (p<0.01) greater BMIs, advanced ages, and higher ALT and AST values when compared to the non-NASH group. ALP was not significantly different between the NAFLD/NASH group and the non-NASH group. The mean BMI of the NAFLD/NASH group (37.3 kg/m2) was approximately 25 percent greater than the BMI of the non-NASH group (28.4 kg/m2). The mean age of the NAFLD/NASH group was 51 years while the non-NASH group’s mean age was 48 years. The mean ALT of the NAFLD/NASH group was 40 IU/L, 27.3 percent greater than in the non-NASH group (ALT at 29.1 IU/L). Among the NAFLD/NASH group the AST was 29.5 IU/L and the non-NASH groups’ AST was 24.8 IU/L. The rates of the co-morbid conditions in the NAFLD/NASH group (DM2=423, MS=447 and PCOS=83) were significantly (p<0.01) higher than the non-NASH group (DM2=242, MS=11 and PCOS=3) as shown below in Figure 1. There was a higher incidence of pre-diabetes in the non-NASH (69 subjects) group than the NAFLD/NASH group (53 subjects). There were 1439 subjects in the non-NASH group who had no co-morbid conditions, whereas the NAFLD/NASH group had a significantly lower number of subjects(15) with no risk factors.

Discussion
The increasing prevalence of NAFLD among the general population is becoming a growing concern because of the possibility that benign steatosis can progress into more serious conditions such as NASH and cirrhosis without any clinical warning or markers.2, 22 Furthermore, the increase in NAFLD is paralleled by an increase of several risk-related conditions including obesity, MS, and DM2.14,12 This study found a high prevalence of NAFLD/NASH in a population from an endocrinology center serving Appalachian Ohio, a geographic area known to have higher incidence of the co-morbid conditions associated with NAFLD.(21) These findings were not unexpected given the location of the study.

Approximately 3 percent of the general population is estimated to have biopsy confirmed NASH.(20) In this study population the rate was 1.3 percent. In another study, the prevalence of NASH as determined by liver biopsy in a severely obese (BMI≥40 kg/m2) bariatric patient population was found to be even higher (36 percent).13 Interestingly, the mean BMI of the NASH group (37.3 kg/m2) was close to 40 kg/m2, but our prevalence rate was significantly lower. This may be due to clinician assumption of the disease state without biopsy, or it may be related to the patient population in the center, a population with other endocrine diseases not related to NAFLD/ NASH, such as hyperthyroidism.

All of the co-morbid conditions except for pre-diabetes were found at significantly higher incidences among the NASH group. Out of the risk factors, MS appears to have the greatest association with NASH. A total of 447 subjects in the NASH group had MS, as compared to 11 in the non-NASH group. This finding supports the belief that MS is the hepatic manifestation of NASH.10,15 Of note, the endocrinology center is likely under-diagnosing metabolic syndrome based on the prevalence (19.6 percent) found in this population compared to national averages.

Currently 44 percent of the adult population 50 years old or older has metabolic syndrome.23 The average age of the study patient population was 50 years, but the recorded prevalence of MS is less than half the national average. Hence, the lower prevalence of diagnosed MS could also have contributed to lowering the overall prevalence of NASH among the study’s population.

Clinically, NAFLD and NASH generally present without symptoms or with nonspecific symptoms such as fatigue or diffuse right upper quadrant pain.24 Although NALFD is the most common cause of elevated liver function tests,25 many patients with NAFLD or NASH will have normal ALT and AST values.26, 22 This study did find a significantly higher value of ALT (40 IU/L) and AST (29.5 IU/L) in the NAFLD/NASH group, as compared to the non-NASH group ALT and AST values (29.1 IU/L and 24.8 IU/L, respectively). Although the NAFLD/NASH groups’ values were significantly higher, the mean values were not out of normal reference range. Of note, some ALT and AST values in the NASH group were as high as 241 IU/L and 293 IU/L, respectively. With the lack of presenting symptoms and reliable serum markers, diagnosis becomes a challenge for physicians.

This study raises other questions concerning NAFLD and NASH that have yet to be answered in order to generate standards for the diagnosis and treatment of NALFD and NASH. The current gold standard for diagnosis of NAFLD and NASH is a liver biopsy.27 However, due to cost, morbidity, and occasional mortality liver biopsies are infrequently used in practice.27

Imaging modalities such as CT scans and MRIs of the liver are often used with high accuracy in determining steatosis, but fail to make the distinction between steatosis and hepatitis, which is paramount in diagnosing NASH.28, 29

Currently, no standard exists among physicians regarding how to diagnose NAFLD or how and when to suspect NASH. Moreover, if a patient has NAFLD or NASH, no proven treatment options exist other than lifestyle modification (i.e. weight loss and exercise) and treatment of associated co-morbid conditions.30

In conclusion, the entire spectrum of NAFLD and its associated co-morbid conditions are being found at alarmingly high prevalence rates. In light of this, physicians need to have a greater awareness of NAFLD/NASH and the potential long term associated sequelae. This is especially pertinent in areas such as Appalachian Ohio where NAFLD/NASH appear to have a much higher prevalence rate of risk factors but may not be diagnosed often enough. The increasing prevalence of NAFLD/NASH, as well as the potential for these to become major public health concerns, justify the need for further research to improve diagnostic and treatment modalities.

Mr. Selinksy, OMS III, is a graduate of Ohio University with a degree in biological sciences, and is currently a third year student at Ohio University College of Osteopathic Medicine (OUCOM). Dr. Shubrook is an assistant professor of Family Medicine for OUCOM and director of the Diabetes Fellowship. Dr. Schwartz is an endocrinologist and associate professor of Specialty Medicine for the OUCOM. Dr. Brannan has 20 years of research experience, published peer-reviewed articles in the areas of population-based behavioral and public health research studies, and has advised on hundreds of physician, resident, and student research projects.

Acknowledgements
A special thanks to Michael Weiser for his editorial work.

Conflicts of Interest: None of the authors have any direct conflicts related to this study. Christopher Selinsky has no conflicts to report. Grace Brannan has no conflicts to report. Jay Shubrook is on the speaker’s bureau for Takeda, Pfizer, Novartis and Merck and has received research support from NovoNordisk, Aventis and Takeda. Frank Schwartz is on the speaker’s bureau for DiaDexux, Novartis, Abbott and has received research support from Medtronic MiniMed, Interthyr Research Foundation.

References

1. Angulo, P. (2002). Nonalcoholic fatty liver disease. The New England Journal of Medicine, 346(16), 1221-1231.
2. Matteoni, C. A., Younossi, Z. M., Gramlich, T., Boparai, N., Liu, Y. C., & McCullough, A. J. (1999). Nonalcoholic fatty liver disease: A spectrum of clinical and pathological severity. Gastroenterology, 116(6), 1413-1419.
3. Bayard, M., Holt, J., & Boroughs, E. (2006). Nonalcoholic fatty liver disease. American Family Physician, 73(11), 1961-1968.
4. Smedile, A., & Bugianesi, E. (2005). Steatosis and hepatocellular carcinoma risk. European review for medical and pharmacological sciences, 9(5), 291-293.
5. Neuschwander-Tetri, B. A., & Caldwell, S. H. (2003). Nonalcoholic steatohepatitis: Summary of an AASLD single topic conference. Hepatology (Baltimore, Md.), 37(5), 1202-1219.
6. Ludwig, J., Viggiano, T. R., McGill, D. B., & Oh, B. J. (1980). Nonalcoholic steatohepatitis: Mayo clinic experiences with a hitherto unnamed disease. Mayo Clinic Proceedings. Mayo Clinic, 55(7), 434-438.
7. Browning, J. D., Szczepaniak, L. S., Dobbins, R., Nuremberg, P., Horton, J. D., Cohen, J. C., et al. (2004). Prevalence of hepatic steatosis in an urban population in the United States: Impact of ethnicity. Hepatology, 40(6), 1387-1395.
8. Szczepaniak, L. S., Nurenberg, P., Leonard, D., Browning, J. D., Reingold, J. S., Grundy, S., et al. (2005). Magnetic resonance spectroscopy to measure hepatic triglyceride content: Prevalence of hepatic steatosis in the general population. American Journal of Physiology: Endocrinology and metabolism, 288(2), E462-8.
9. Kelley, D. E., McKolanis, T. M., Hegazi, R. A., Kuller, L. H., & Kalhan, S. C. (2003). Fatty liver in type 2 diabetes mellitus: Relation to regional adiposity, fatty acids, and insulin resistance. American Journal of Physiology: Endocrinology and metabolism, 285(4), E906-16.
10. Marchesini, G., & Marzocchi, R. (2007). Metabolic syndrome and NASH. Clinics in Liver Disease, 11(1), 105-117.
11. Setji, T. L., Holland, N. D., Sanders, L. L., Pereira, K. C., Diehl, A. M., & Brown, A. J. (2006). Nonalcoholic steatohepatitis and nonalcoholic fatty liver disease in young women with polycystic ovary syndrome. The Journal of Clinical Endocrinology and Metabolism, 91(5), 1741-1747.
12. Wang, Y., & Beydoun, M. A. (2007). The obesity epidemic in the United States--gender, age, socioeconomic, Racial/Ethnic, and geographic characteristics: A systematic review and meta-regression analysis. Epidemiologic Reviews.
13. Gholam, P. M., Flancbaum, L., Machan, J. T., Charney, D. A., & Kotler, D. P. (2007). Nonalcoholic fatty liver disease in severely obese subjects. The American Journal of Gastroenterology, 102(2), 399-408.
14. Park, Y. W., Zhu, S., Palaniappan, L., Heshka, S., Carnethon, M. R., & Heymsfield, S. B. (2003). The metabolic syndrome: Prevalence and associated risk factor findings in the US population from the third national health and nutrition examination survey, 1988-1994. Archives of Internal Medicine, 163(4), 427-436.
15. Powell, E. E., Jonsson, J. R., & Clouston, A. D. (2005). Dangerous liaisons: The metabolic syndrome and nonalcoholic fatty liver disease. Annals of Internal Medicine, 143(10), 753-754.
16. Fan, J. G., Zhu, J., Li, X. J., Chen, L., Lu, Y. S., Li, L., et al. (2005). Fatty liver and the metabolic syndrome among shanghai adults. Journal of Gastroenterology and Hepatology, 20(12), 1825-1832.
17. Targher, G., Bertolini, L., Padovani, R., Rodella, S., Tessari, R., Zenari, L., et al. (2007). Prevalence of nonalcoholic fatty liver disease and its association with cardiovascular disease among type 2 diabetic patients. Diabetes Care, 30(5), 1212-1218.
18. Gambarin-Gelwan, M., Kinkhabwala, S. V., Schiano, T. D., Bodian, C., Yeh, H. C., & Futterweit, W. (2007). Prevalence of nonalcoholic fatty liver disease in women with polycystic ovary syndrome. Clinical Gastroenterology and Hepatology: the official clinical practice journal of the American Gastroenterological Association, 5(4), 496-501.
19. McCullough, A. J. (2002). Update on nonalcoholic fatty liver disease. Journal of Clinical Gastroenterology, 34(3), 255-262.
20. Wanless, I. R., & Lentz, J. S. (1990). Fatty liver hepatitis (steatohepatitis) and obesity: An autopsy study with analysis of risk factors. Hepatology (Baltimore, Md.), 12(5), 1106-1110.
21. Schwartz, F., Boyd, S., Shubrook, J., Denham, S., Issac, S., Ruhil, A., et al. (2007). The high prevalence of diabetes mellitus and atherosclerosis in Appalachian Ohio. Under review at Journal of Rural Health.
22. Shalhub, S., Parsee, A., Gallagher, S. F., Haines, K. L., Willkomm, C., Brantley, S. G., et al. (2004). The importance of routine liver biopsy in diagnosing nonalcoholic steatohepatitis in bariatric patients. Obesity Surgery : the official journal of the American Society for Bariatric Surgery and of the Obesity Surgery Society of Australia and New Zealand, 14(1), 54-59.
23. Alexander, C. M., Landsman, P. B., Teutsch, S. M., Haffner, S. M., Third National Health and Nutrition Examination Survey (NHANES III), & National Cholesterol Education Program (NCEP). (2003). NCEP-defined metabolic syndrome, diabetes, and prevalence of coronary heart disease among NHANES III participants age 50 years and older. Diabetes, 52(5), 1210-1214.
24. Wieckowska, A., McCullough, A. J., & Feldstein, A. E. (2007). Noninvasive diagnosis and monitoring of nonalcoholic steatohepatitis: Present and future. Hepatology (Baltimore, Md.), 46(2), 582-589.
25. Mendez-Sanchez, N., Arrese, M., Zamora-Valdes, D., & Uribe, M. (2007). Current concepts in the pathogenesis of nonalcoholic fatty liver disease. Liver International : official journal of the International Association for the Study of the Liver, 27(4), 423-433.
26. Mofrad, P., Contos, M. J., Haque, M., Sargeant, C., Fisher, R. A., Luketic, V. A., et al. (2003). Clinical and histologic spectrum of nonalcoholic fatty liver disease associated with normal ALT values. Hepatology (Baltimore, Md.), 37(6), 1286-1292.
27. Adams, L. A., & Angulo, P. (2007). Role of liver biopsy and serum markers of liver fibrosis in non-alcoholic fatty liver disease. Clinics in Liver Disease, 11(1), 25-35.
28. Lupsor, M., & Badea, R. (2005). Imaging diagnosis and quantification of hepatic steatosis: Is it an accepted alternative to needle biopsy? Romanian Journal of Gastroenterology, 14(4), 419-425.
29. Saadeh, S., Younossi, Z. M., Remer, E. M., Gramlich, T., Ong, J. P., Hurley, M., et al. (2002). The utility of radiological imaging in nonalcoholic fatty liver disease. Gastroenterology, 123(3), 745-750.
30. Adams, L. A., & Angulo, P. (2006). Treatment of non-alcoholic fatty liver disease. Postgraduate Medical Journal, 82(967), 315-322.