Secondary Outcomes
Histologic Features
As compared with the placebo group, both active-treatment groups had a significant reduction in steatosis, lobular inflammation (Fig. 1 in the Supplementary Appendix), and the activity score for nonalcoholic fatty liver disease (Table 2). Although scores for hepatocellular ballooning were improved with vitamin E and with pioglitazone, only the improvement with vitamin E was significant (P=0.01). Fibrosis scores were not significantly improved with either active treatment. Steatohepatitis resolved in a greater proportion of subjects receiving either vitamin E or pioglitazone than in those receiving placebo, but the difference was significant only for those receiving pioglitazone (P=0.001) (Table 2).
Serum Enzyme Levels and Liver Test Results
There was an early and highly significant decrease in mean aspartate aminotransferase and alanine aminotransferase levels among subjects receiving vitamin E and among subjects receiving pioglitazone (Figure 2FIGURE 2
Changes from Baseline in Aminotransferase Levels, Insulin Resistance, and Weight, According to Study Group.
). These changes occurred in the first 24 weeks and were sustained throughout the period in which the subjects were receiving treatment. Serum concentrations of alkaline phosphatase and γ-glutamyl transpeptidase also improved in the two active-drug groups, but bilirubin levels did not change significantly.
Body Weight, Insulin Resistance, and Quality of Life
There was a significant improvement in insulin resistance only in the pioglitazone group, but that group was also the only group that had a significant mean weight gain (a mean increase of 4.7 kg at week 96, P<0.001 for the comparison with placebo) (Table 3TABLE 3
Changes in Serum Biochemical Levels, Metabolic Factors, and Quality of Life from Baseline to 96 Weeks.
). These changes were noted by week 24, and the weight gain progressed over the course of the study. Although insulin resistance returned to the baseline value after discontinuation of pioglitazone, the associated weight gain was not reversed. Changes in quality of life, as assessed by the scores for both the mental and physical components of the SF-36, did not differ significantly between the vitamin E group or the pioglitazone group and the placebo group (Table 3).
Adverse Events
With the exception of weight gain, the overall distribution of individual adverse events did not differ significantly across the study groups. There were 19 severe adverse events — 10 in the placebo group, 7 in the vitamin E group, and 2 in the pioglitazone group (see Table 3 in the Supplementary Appendix for details). A similar number of cardiovascular events occurred among subjects taking placebo (12 events), those taking vitamin E (12), and those taking pioglitazone (10). No cases of congestive heart failure were reported. The frequency of bone fractures was also similar across study groups: five in the placebo group, three in the vitamin E group, and three in the pioglitazone group. During the 96 weeks of the study, diabetes developed in four subjects who were receiving vitamin E but in none of the subjects who were receiving placebo or pioglitazone (P=0.12 for the comparison of vitamin E with placebo). Symptoms and signs of cirrhosis (thrombocytopenia, anasarca, and hyperbilirubinemia) developed in one patient in the vitamin E group who had had bridging hepatic fibrosis at entry, and that patient died of sepsis. No cases of serious hepatotoxicity requiring permanent discontinuation of the study drug were reported.
DISCUSSION
The assessment of therapeutic agents for nonalcoholic steatohepatitis is a complex process. Because there are no validated biomarkers of response to treatment, one must rely on histologic assessment of a liver-biopsy specimen for this purpose. The activity score for nonalcoholic fatty liver disease quantifies the severity of steatosis, hepatocellular ballooning, and inflammation — the key histologic components of the disease.17 A decrease in their severity occurs with amelioration of the disease; however, the severity of these components (especially hepatic steatosis) may also decrease with progression of fibrosis to cirrhosis.20,21
To develop an outcome that was both quantifiable and clinically relevant, the requirements of an improvement in ballooning and no worsening of fibrosis were added to the requirement of a decrease in the nonalcoholic fatty liver disease activity score for the primary outcome. This makes it likely that the observed improvements with vitamin E are both statistically and clinically significant. These improvements are also concordant with those in previous small, pilot trials.12,13 These data cannot, however, be generalized to patients with diabetes or to those with cirrhosis, and additional clinical trials both to confirm these findings and to determine the generalizability of the data are warranted.
Although pioglitazone did not meet the prespecified significance level for the primary outcome, it was associated with highly significant reductions in steatosis, inflammation, and hepatocellular ballooning, as well as with improvements in insulin resistance and liver-enzyme levels (Table 2 and Figure 2). It also led to the resolution of steatohepatitis in a significant proportion of subjects. One possible reason for the failure to achieve the primary outcome with pioglitazone therapy, even though it significantly improved individual features of nonalcoholic steatohepatitis, is that more subjects in the pioglitazone group than in the vitamin E and placebo groups were classified as not having had ballooning, on the basis of the planned central review of deeper cuts of baseline biopsy specimens, and a reduction in ballooning was one of the criteria for the primary outcome. The discrepancies between the results of liver histologic assessments that were performed locally to determine eligibility and the results of assessments of deeper cuts of the same tissue block that were performed centrally to determine histologic baseline and outcome measures for use in the study analyses may have been due to interobserver variability, variable distribution of histologic findings in the different tissue sections, or a potential bias due to the unblinded nature of the local pathological review to determine eligibility.22-24
It is important not to overinterpret the data on adverse events in this trial because the study was not powered to test any safety-related hypotheses. The risk of bone fracture was not increased with pioglitazone25; however, the number of postmenopausal women included in the trial was too small to assess any potential effect. Although diabetes developed in subjects in the vitamin E group but not in subjects in the other two groups, only four subjects were affected, and this number is smaller than the number that would be expected in this patient population. Finally, cardiovascular events occurred with equal frequency in all three study groups, but, again, the trial was much too small to detect meaningful differences in the incidence of cardiovascular events.
Enthusiasm for the potential benefits of pioglitazone and vitamin E must be tempered by the finding that there was an improvement in histologic features in only 34% of the subjects who received pioglitazone and 43% of those who received vitamin E, and steatohepatitis resolved in only 47% and 36% of the subjects in those two groups, respectively. Neither agent was associated with a significant improvement in the mean fibrosis score after 96 weeks of treatment. There was also no significant reduction in portal inflammation, which has been linked to advanced disease.4,26 Given the certainty of relapse after discontinuation of the drug, it is likely that whichever drug is prescribed for nonalcoholic steatohepatitis, it will need to be taken indefinitely.13,27 The weight gain among the subjects receiving pioglitazone — which did not resolve after discontinuation of the drug — also detracts from its long-term usefulness. The unknown long-term potential for adverse events with vitamin E and pioglitazone therapies must be factored into the decision about whether to use these agents.25,28,29
The decision about which specific therapy to use for the treatment of nonalcoholic steatohepatitis should include a consideration of both the efficacy and the toxic effects of the therapy as compared with those of other available therapies. Preliminary studies provide a rationale for the use of lifestyle intervention, bariatric surgery, phlebotomy, and a variety of drugs. However, the usefulness of each of these therapeutic options has not been validated in rigorously performed, randomized, controlled trials. Our study provides such evidence for vitamin E and pioglitazone; however, this trial was not designed to compare vitamin E with pioglitazone, and no conclusions can be drawn about their relative efficacy.
In summary, the results of this trial of pioglitazone and vitamin E for the treatment of nonalcoholic steatohepatitis in adults without diabetes showed that vitamin E was superior to placebo and suggested that pioglitazone may also have efficacy. Although only subjects who received vitamin E met the criteria for the prespecified primary outcome measure, subjects who received pioglitazone had significant improvement in other important histologic features of nonalcoholic steatohepatitis.
Supported by grants (U01DK61718, U01DK61728, U01DK61731, U01DK61732, U01DK61734, U01DK61737, U01DK61738, U01DK61730, and U01DK61713) from the National Institutes of Health (NIH), by the intramural program of the National Cancer Institute, and by NIH General Clinical Research Center grants or Clinical and Translational Science Awards (UL1RR024989, UL1RR024128, M01RR000750, UL1RR024131, M01RR000827, UL1RR025014, and M01RR000065). Additional funding was provided by Takeda Pharmaceuticals North America through a Cooperative Research and Development Agreement with the NIH. The vitamin E softgels and matching placebo were provided by Pharmavite through a Clinical Trial Agreement with the NIH.
Dr. Sanyal reports receiving consulting fees from Exalenz, Takeda Pharmaceuticals North America, Norgine, Astellas, and Amylin, grant support from Intercept Pharmaceuticals, Gilead, Roche, Salix Pharmaceuticals, Sanofi-Aventis, Otsuka, and Orphan Therapeutics, and royalties from UpToDate; Dr. Neuschwander-Tetri, consulting fees from Gilead, Astellas, Amylin, Centocor, Vertex, and Sanofi-Aventis and reimbursements for travel or accommodations expenses from Astellas and Gilead; Dr. Kowdley, consulting fees from Gilead, Novartis, Bristol-Myers Squibb, and Vertex, gifts from Roche, honoraria from Bristol-Myers Squibb, Schering-Plough (now Merck), and Roche, lecture fees from Bristol-Myers Squibb, grant support from Intercept, Schering-Plough (now Merck), and royalties from UpToDate; Dr. Diehl, consulting fees and reimbursements for travel or accommodations from CellszDirect and Vertex, and grant support from Norgine and Gilead; Dr. Bass, consulting fees from Genentech and Norgine; and Dr. Chalasani, consulting fees from Gilead, Genentech, Amylin, Pfizer, Advanced Life Sciences, Metabasis (now Ligand Pharmaceuticals), AtheroGenics, Karo Bio, Debiovision, Eli Lilly, Johnson & Johnson, Teva Pharmaceuticals, Abbott, Norgine, Ockham, and Salix Pharmaceuticals, grant support from Gilead, Eli Lilly, Debiovision, and Monarch LifeSciences, reimbursements for travel and accommodations from Salix Pharmaceuticals, Gilead, Genentech, Advanced Life Sciences, Amylin, Metabasis (now Ligand Pharmaceuticals), AtheroGenics, Johnson & Johnson, Debiovision and Pfizer, and fees for serving on the data and safety monitoring board for Takeda and being named on patents pending for biomarkers of nonalcoholic steatohepatitis held by Indiana University. Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.