Abstract
Introduction
The aim of the study was to investigate the significance of factors associated with minimal hepatic encephalopathy (MHE) in cirrhotic patients.
Material and methods
Between September 2012 and August 2013, 60 cirrhotic patients, including MHE and non-MHE (NMHE) patients, were included in the study. Associated factors and clinical factors were analyzed to see if they were significantly different between MHE and non-MHE patients. Upon identifying the factors showing differences, we applied multivariate regression analysis to further decide which were the most significant ones to differentiate MHE from NMHE patients.
Results
There were 26 patients diagnosed with MHE and 34 with NMHE. Our results demonstrated that the prevalence rate of small intestinal bacterial overgrowth (SIBO) was highly associated with patients with MHE (65.4%, 17 out of 26), in contrast to the rate in NMHE patients (8.8%, 3 out of 34). We also found that factors including age, education level, intelligent test results, plasma albumin level and plasma ammonia levels were significantly different between MHE and NMHE patients. Ultimately, with logistic regression analysis, we found that SIBO was the most significant factor differentiating MHE patients from NMHE patients (p < 0.05).
Conclusions
In cirrhotic patients, SIBO was highly associated with MHE. This may further our understanding of the mechanisms of MHE and help to develop potential therapeutic interventions to treat cirrhotic patients with MHE.
Keywords: small intestinal bacterial overgrowth, minimal hepatic encephalopathy, multivariate regression analysis
Introduction
Hepatic encephalopathy (HE) is a severe condition of liver cirrhosis that includes a series of neurologic and neuropsychiatric complications [1, 2]. Minimal HE (MHE) is the mildest form of HE. It may happen to certain patients with chronic liver disease without obvious symptoms of hepatic encephalopathy. However, clinical manifestations and biochemical abnormalities could be detected with a fine intelligence test or comprehensive neurophysiological examination [3]. Studies have shown that patients with MHE had significant difficulties in various aspects of their lives, including social activities, emotions, sleep and work [4–6]. Thus, early detection and treatment of MHE, especially among cirrhotic patients, bear significant implications for the clinical and research societies [7, 8].
In the present study, we examined clinical factors and associations between MHE and non-MHE (NMHE) cirrhotic patients. We also applied multivariate regression analysis to determine the most significant factors that can differentiate MHE patients from NMHE patients. The purpose of the study was to further our understanding of the mechanisms of MHE and seek potential therapeutic methods to treat MHE in patients with cirrhosis.
Material and methods
Patients
Between September 2012 and August 2013, there were 60 cirrhotic patients enrolled in our department, 46 males and 14 females, aged between 36 and 68 years, with a mean age of 48.9 ±9.74 years. All patients signed the consent forms. All experimental and clinical procedures were reviewed and approved by the Ethics Committee at the Wei Fang People's Hospital. For educational levels, all patients held high school diplomas or received a higher education. There were 54 cases of hepatitis B cirrhosis, 2 cases of hepatitis C cirrhosis and 4 cases of alcoholic cirrhosis. Based on the Child-Pugh classification, there were 21 cases of Child-Pugh grade A, 26 cases of grade B and 13 cases of grade C.
Patients were included in the study if they had not been using any antibiotics, lactulose, antacids, or other drugs affecting gastrointestinal motility in the past 2–4 weeks; had no diarrhea, abdominal pain, bloating or other symptoms; had not used any prednisone, antidepressants, opioids or other drugs before; had no recent history of severe cardiopulmonary disease, renal insufficiency, diabetes, adverse gastrointestinal diseases or extrahepatic disease caused by chronic diarrhea; had no previous history of abdominal surgery, spontaneous bacterial peritonitis or other sorts of infections. Patients with hearing or vision difficulties, or poor education, were also excluded from the study.
Diagnosis of minimal hepatic encephalopathy
The patients were tested with combined intelligence tests, including number connection test A (NCT-A), number connection test BC (NCT-BC) and the digit symbol test (DST) [9]. The definition of MHE was based on psychometric test results that were two SD more than normal on at least two psychometric tests [3].
Glucose hydrogen breath test
The detection of small intestinal bacterial overgrowth (SIBO) was conducted by the glucose hydrogen breath test (GHBT). Briefly, it was performed after an overnight fast, beginning between 7:00 and 9:00 AM. Each patient received 1 g per kg body weight D-glucose (Merck AG, Darmstadt, Germany). Following three tries, breath samples (50 ml) were retrieved after the initial 300 ml of exhaled air. Breath samples were then collected before, and every 30 min during the 3-hour period after the intake of glucose. If the breath H2 level rose above baseline by at least 12 ppm, it was determined to be a case of bacterial overgrowth.
Ammonia detection
The peripheral venous blood (3 ml) was taken from each patient in the morning after overnight fasting and at least one day of a low protein diet. The reference value of plasma ammonia concentration was between 11.2 and 55.3 µmol/l.
Statistical analysis
Statistical analysis was performed with SPSS 17.0 software. The data were presented as mean ± standard deviations. For univariate analysis on qualitative data, the χ2 test was used. For quantitative data, the t test was used. For multivariable analysis, logistic regression analysis was used. Statistical significance was determined if p < 0.05.
Results
Small intestinal bacterial overgrowth was highly associated with minimal hepatic encephalopathy
After combined intelligence tests, 26 out of 60 patients were diagnosed with MHE. We then compared the associated factors between MHE and NMHE patients (Table I). Our results showed that there were no differences among factors such as gender, causes of disease or Child-Pugh classification between the two groups. Interestingly, the results showed that the prevalence rate of SIBO was very high in patients with MHE (65.4%, 17 out of 26), whereas the prevalence rate of SIBO was low in NMHE patients (9.7%, 3 out of 34). Statistical analysis demonstrated that the difference in SIBO prevalence rate between MHE and NMHE patients was significant (p < 0.01, Table I). Thus, our results demonstrated that the occurrence of SIBO was highly associated with MHE.
Table I.
Associated factors among MHE and NMHE patients. Small intestinal bacterial overgrowth (SIBO) was highly associated with patients with MHE (p < 0.01)
| Associated factors | MHE (n = 26) | NMHE (n = 34) | Value of p | |
|---|---|---|---|---|
| Gender | Male | 19 | 27 | 0.56 |
| Female | 7 | 7 | ||
| Cause of disease | Known | 23 | 31 | 0.73 |
| Unknown | 3 | 3 | ||
| Child-Pugh classification | A + B | 19 | 28 | 0.39 |
| C | 7 | 6 | ||
| Esophageal varices | Positive | 20 | 27 | 0.81 |
| Negative | 6 | 7 | ||
| Ascites | Positive | 11 | 12 | 0.58 |
| Negative | 15 | 22 | ||
| SIBO | Positive | 17 | 3 | < 0.01 |
| Negative | 9 | 31 |
Some of the clinical factors were highly associated with minimal hepatic encephalopathy
In order to closely examine the mechanisms of the high prevalence rate of SIBO in MHE patients, we next compared the clinical factors between patients with MHE and NMHE patients (Table II). We found that there were no differences in total bilirubin or direct bilirubin between MHE and NMHE patients. However, some of the factors, such as age, education levels, intelligent test results, plasma albumin level and plasma ammonia levels, were significantly different between MHE patients and NMHE patients.
Table II.
Comparison of clinical factors between MHE and NMHE patients. NCT-A, number connection test A. NCT-BC, number connection test BC
| Clinical factors | MHE (n = 26) | NMHE (n = 34) | Value of t | Value of p | ||
|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | |||
| Age [years] | 51.3 | 9.2 | 46.1 | 8.9 | 2.21 | 0.03 |
| Education [years] | 10.5 | 3.4 | 13.8 | 4.2 | 3.26 | < 0.01 |
| NCT-A | 68.4 | 9.6 | 53.6 | 4.8 | 7.03 | < 0.01 |
| NCT-BC | 60.7 | 6.5 | 50.2 | 4.4 | 7.47 | < 0.01 |
| Total bilirubin [µmol/l] | 14.2 | 3.2 | 12.7 | 3.7 | 1.64 | 0.10 |
| Direct bilirubin [µmol/l] | 10.3 | 4.5 | 9.2 | 3.9 | 1.01 | 0.31 |
| Plasma albumin [g/l] | 37.5 | 7.4 | 42.0 | 9.4 | 2.14 | 0.03 |
| PT [s] | 11.1 | 3.5 | 13.1 | 3.7 | 2.12 | 0.03 |
| Plasma ammonia [µmol/l] | 48.7 | 8.8 | 34.9 | 7.5 | 6.55 | < 0.01 |
| Child score | 7.48 | 2.7 | 6.37 | 2.6 | 1.61 | 0.11 |
Small intestinal bacterial overgrowth was the most significant factor in patients with minimal hepatic encephalopathy
Since we discovered that several associated factors and clinical factors were significantly different between MHE and NMHE patients, we applied multivariate logistic regression analysis to examine which factor was the most significant one to differentiate MHE patients from NMHE patients. Our results showed that SIBO was the most significant factor among MHE patients (Table III).
Table III.
Multivariate logistic regression analysis showed that SIBO was the most significant factor among MHE patients
| Variables | Odds ratio | 95% CI | Value of p | |
|---|---|---|---|---|
| Lower | Upper | |||
| Age | 1.14 | 1.07 | 1.26 | < 0.001 |
| Education level | 0.51 | 0.41 | 0.62 | < 0.001 |
| Plasma albumin | 1.12 | 0.80 | 1.58 | 0.02 |
| Plasma ammonia | 1.24 | 1.13 | 1.36 | < 0.001 |
| SIBO | 1.36 | 1.22 | 1.51 | < 0.001 |
Discussion
The likelihood of cirrhotic patients developing MHE is very high. Globally, the prevalence rate of MHE among cirrhotic patients ranges from 30% to 90% [10–13], and the estimated level is well above 50% in Chinese patients [14]. The major finding of the present study is that SIBO was more prevalent in cirrhotic patients with MHE than the patients without MHE. The percentage of cirrhotic patients with MHE in our study was 43.3%, similar to previous studies [15–17].
We demonstrated, in the present study, that other clinical factors were also associated with MHE, such as age [18], plasma albumin [19], or the possibility of developing overt encephalopathy [20]. The MHE patients had higher levels of intestinal bacteria and plasma ammonia, as compared with NMHE patients. Previous studies showed that the prevalence of intestinal bacterial overgrowth was very high, and correlated with bacterial DNA translocation in patients with cirrhosis [21, 22]. This is consistent with our results showing that in MHE patients the prevalence rate of SIBO was dramatically unregulated as Child-Pugh scores increased. Thus, it is very likely that SIBO actively led to severe deterioration of liver function.
There are several limits worth noting in the current study. First, the patients included in the current study were mostly diagnosed with hepatitis B cirrhosis. While both hepatitis B and hepatitis C viruses are common causes of cirrhosis, the possible explanation for the unbalanced sampling in the present study would be that the Chinese population (or Asian-Pacific population) in particular is more likely to develop hepatitis B than hepatitis C [23, 24]. Further study with a larger sample size of western cirrhotic patients would help us gain more insights into the relationship between SIBO and MHE. Second, the diagnostic method for SIBO in the present study was GHBT, instead of the gold standard of culture. We used GHBT as it was easy to perform and the results were quickly available to the physicians. However, it is possible to get negative GHBT results in patients with SIBO as the glucose in the distal part of the intestinal ducts was already digested. Other tests, such as endoscopy and quantitative cultures, would be more accurate and thus complementary to GHBT for diagnosing SIBO in patients. Finally, we did not conduct extensive research on the correlation of other factors with SIBO in affecting MHE in cirrhotic patients. For example, studies showed that plasma ammonia was an important factor to determine the inflammation in MHE patients, and improving the microenvironment could substantially help MHE patients to achieve better neuropsychological functions [25, 26]. Future study would be needed to further explore the associations of SIBO with other factors, including plasma ammonia, in the diagnosis and treatment of cirrhotic patients with MHE.
In conclusion, our results clearly demonstrated that in cirrhotic patients SIBO was highly associated with MHE. This information would undoubtedly further our understanding on the mechanisms of SIBO development and its direct effect on development of MHE in cirrhotic patients. Moreover, it may help to develop early diagnostic methods and potential therapeutic interventions targeting SIBO to treat HE patients.
Conflict of interest
The authors declare no conflict of interest.
References
- 1.Mullen KD, Prakash RK. New perspectives in hepatic encephalopathy. Clin Liver Dis. 2012;16:1–5. doi: 10.1016/j.cld.2012.01.001. [DOI] [PubMed] [Google Scholar]
- 2.Romero-Gomez M, Boza F, Garcia-Valdecasas MS, Garcia E, Aguilar-Reina J. Subclinical hepatic encephalopathy predicts the development of overt hepatic encephalopathy. Am J Gastroenterol. 2001;96:2718–23. doi: 10.1111/j.1572-0241.2001.04130.x. [DOI] [PubMed] [Google Scholar]
- 3.Kharbanda PS, Saraswat VA, Dhiman RK. Minimal hepatic encephalopathy: diagnosis by neuropsychological and neurophysiologic methods. Indian J Gastroenterol. 2003;22(Suppl.2):S37–41. [PubMed] [Google Scholar]
- 4.Prasad S, Dhiman RK, Duseja A, Chawla YK, Sharma A, Agarwal R. Lactulose improves cognitive functions and health-related quality of life in patients with cirrhosis who have minimal hepatic encephalopathy. Hepatology. 2007;45:549–59. doi: 10.1002/hep.21533. [DOI] [PubMed] [Google Scholar]
- 5.Arguedas MR, DeLawrence TG, McGuire BM. Influence of hepatic encephalopathy on health-related quality of life in patients with cirrhosis. Dig Dis Sci. 2003;48:1622–6. doi: 10.1023/a:1024784327783. [DOI] [PubMed] [Google Scholar]
- 6.Schomerus H, Hamster W. Quality of life in cirrhotics with minimal hepatic encephalopathy. Metab Brain Dis. 2001;16:37–41. doi: 10.1023/a:1011610427843. [DOI] [PubMed] [Google Scholar]
- 7.Ciećko-Michalska IM, Dziedzic T, Słowik A, et al. Liver and brain metabolism alterations in patients with minimal hepatic encephalopathy. Prz Gastroenterol. 2013;8:115–9. [Google Scholar]
- 8.Gwozdzinski L, Krawczyk P, Dworniak D, Kowalczyk E, Blaszczyk J. Alterations in the erythrocyte plasma membranes in patients with alcohol-induced liver cirrhosis – preliminary results. Arch Med Sci. 2011;7:87–91. doi: 10.5114/aoms.2011.20609. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Ferenci P, Lockwood A, Mullen K, Tarter R, Weissenborn K, Blei AT. Hepatic encephalopathy: definition, nomenclature, diagnosis, and quantification: final report of the working party at the 11th World Congresses of Gastroenterology, Vienna, 1998. Hepatology. 2002;35:716–21. doi: 10.1053/jhep.2002.31250. [DOI] [PubMed] [Google Scholar]
- 10.Saxena N, Bhatia M, Joshi YK, Garg PK, Dwivedi SN, Tandon RK. Electrophysiological and neuropsychological tests for the diagnosis of subclinical hepatic encephalopathy and prediction of overt encephalopathy. Liver. 2002;22:190–7. doi: 10.1034/j.1600-0676.2002.01431.x. [DOI] [PubMed] [Google Scholar]
- 11.Liu Q, Duan ZP, Ha DK, Bengmark S, Kurtovic J, Riordan SM. Synbiotic modulation of gut flora: effect on minimal hepatic encephalopathy in patients with cirrhosis. Hepatology. 2004;39:1441–9. doi: 10.1002/hep.20194. [DOI] [PubMed] [Google Scholar]
- 12.Dhiman RK, Sawhney MS, Chawla YK, Das G, Ram S, Dilawari JB. Efficacy of lactulose in cirrhotic patients with subclinical hepatic encephalopathy. Dig Dis Sci. 2000;45:1549–52. doi: 10.1023/a:1005556826152. [DOI] [PubMed] [Google Scholar]
- 13.Senzolo M, Amodio P, D'Aloiso MC, et al. Neuropsychological and neurophysiological evaluation in cirrhotic patients with minimal hepatic encephalopathy undergoing liver transplantation. Transplant Proc. 2005;37:1104–7. doi: 10.1016/j.transproceed.2004.12.265. [DOI] [PubMed] [Google Scholar]
- 14.Zeng Z, Li YY, Nie YQ. [An epidemiological survey of subclinical hepatic encephalopathy] Zhonghua Gan Zang Bing Za Zhi. 2003;11:680–2. [PubMed] [Google Scholar]
- 15.Ortiz M, Jacas C, Cordoba J. Minimal hepatic encephalopathy: diagnosis, clinical significance and recommendations. J Hepatol. 2005;42(Suppl. 1):S45–53. doi: 10.1016/j.jhep.2004.11.028. [DOI] [PubMed] [Google Scholar]
- 16.Romero-Gomez M, Cordoba J, Jover R, et al. Value of the critical flicker frequency in patients with minimal hepatic encephalopathy. Hepatology. 2007;45:879–85. doi: 10.1002/hep.21586. [DOI] [PubMed] [Google Scholar]
- 17.Bajaj JS, Hafeezullah M, Franco J, et al. Inhibitory control test for the diagnosis of minimal hepatic encephalopathy. Gastroenterology. 2008;135:1591–600. doi: 10.1053/j.gastro.2008.07.021. [DOI] [PubMed] [Google Scholar]
- 18.Quero JC, Hartmann IJ, Meulstee J, Hop WC, Schalm SW. The diagnosis of subclinical hepatic encephalopathy in patients with cirrhosis using neuropsychological tests and automated electroencephalogram analysis. Hepatology. 1996;24:556–60. doi: 10.1002/hep.510240316. [DOI] [PubMed] [Google Scholar]
- 19.Malaguarnera M, Greco F, Barone G, Gargante MP, Toscano MA. Bifidobacterium longum with fructo-oligosaccharide (FOS) treatment in minimal hepatic encephalopathy: a randomized, double-blind, placebo-controlled study. Dig Dis Sci. 2007;52:3259–65. doi: 10.1007/s10620-006-9687-y. [DOI] [PubMed] [Google Scholar]
- 20.Groeneweg M, Moerland W, Quero JC, Hop WC, Krabbe PF, Schalm SW. Screening of subclinical hepatic encephalopathy. J Hepatol. 2000;32:748–53. doi: 10.1016/s0168-8278(00)80243-3. [DOI] [PubMed] [Google Scholar]
- 21.Pande C, Kumar A, Sarin SK. Small-intestinal bacterial overgrowth in cirrhosis is related to the severity of liver disease. Aliment Pharmacol Ther. 2009;29:1273–81. doi: 10.1111/j.1365-2036.2009.03994.x. [DOI] [PubMed] [Google Scholar]
- 22.Gupta A, Dhiman RK, Kumari S, et al. Role of small intestinal bacterial overgrowth and delayed gastrointestinal transit time in cirrhotic patients with minimal hepatic encephalopathy. J Hepatol. 2010;53:849–55. doi: 10.1016/j.jhep.2010.05.017. [DOI] [PubMed] [Google Scholar]
- 23.Liaw YF, Leung N, Kao JH, et al. Asian-Pacific consensus statement on the management of chronic hepatitis B: a 2008 update. Hepatol Int. 2008;2:263–83. doi: 10.1007/s12072-008-9080-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Liaw YF, Leung N, Guan R, et al. Asian-Pacific consensus statement on the management of chronic hepatitis B: a 2005 update. Liver Int. 2005;25:472–89. doi: 10.1111/j.1478-3231.2005.01134.x. [DOI] [PubMed] [Google Scholar]
- 25.Ong JP, Aggarwal A, Krieger D, et al. Correlation between ammonia levels and the severity of hepatic encephalopathy. Am J Med. 2003;114:188–93. doi: 10.1016/s0002-9343(02)01477-8. [DOI] [PubMed] [Google Scholar]
- 26.Shawcross DL, Wright G, OldeDamink SW, Jalan R. Role of ammonia and inflammation in minimal hepatic encephalopathy. Metab Brain Dis. 2007;22:125–38. doi: 10.1007/s11011-006-9042-1. [DOI] [PubMed] [Google Scholar]