Efficacy of somatostatin and vasopressin in the control of acute variceal hemorrhage

Treatment for bleeding oesophageal varices in people with decompensated liver cirrhosis: a network meta-analysis

BACKGROUND

Approximately 40% to 95% of people with liver cirrhosis have oesophageal varices. About 15% to 20% of oesophageal varices bleed within about one to three years after diagnosis. Several different treatments are available, including, among others, endoscopic sclerotherapy, variceal band ligation, somatostatin analogues, vasopressin analogues, and balloon tamponade. However, there is uncertainty surrounding the individual and relative benefits and harms of these treatments.

OBJECTIVES

To compare the benefits and harms of different initial treatments for variceal bleeding from oesophageal varices in adults with decompensated liver cirrhosis, through a network meta-analysis; and to generate rankings of the different treatments for acute bleeding oesophageal varices, according to their benefits and harms.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, World Health Organization International Clinical Trials Registry Platform, and trials registers until 17 December 2019, to identify randomised clinical trials (RCTs) in people with cirrhosis and acute bleeding from oesophageal varices.

SELECTION CRITERIA

We included only RCTs (irrespective of language, blinding, or status) in adults with cirrhosis and acutely bleeding oesophageal varices. We excluded RCTs in which participants had bleeding only from gastric varices, those who failed previous treatment (refractory bleeding), those in whom initial haemostasis was achieved before inclusion into the trial, and those who had previously undergone liver transplantation.

DATA COLLECTION AND ANALYSIS

We performed a network meta-analysis with OpenBUGS software, using Bayesian methods, and calculated the differences in treatments using odds ratios (OR) and rate ratios with 95% credible intervals (CrI) based on an available-case analysis, according to National Institute of Health and Care Excellence Decision Support Unit guidance. We performed also the direct comparisons from RCTs using the same codes and the same technical details.

MAIN RESULTS

We included a total of 52 RCTs (4580 participants) in the review. Forty-eight trials (4042 participants) were included in one or more comparisons in the review. The trials that provided the information included people with cirrhosis due to varied aetiologies and those with and without a previous history of bleeding. We included outcomes assessed up to six weeks. All trials were at high risk of bias. A total of 19 interventions were compared in the trials (sclerotherapy, somatostatin analogues, vasopressin analogues, sclerotherapy plus somatostatin analogues, variceal band ligation, balloon tamponade, somatostatin analogues plus variceal band ligation, nitrates plus vasopressin analogues, no active intervention, sclerotherapy plus variceal band ligation, balloon tamponade plus sclerotherapy, balloon tamponade plus somatostatin analogues, balloon tamponade plus vasopressin analogues, variceal band ligation plus vasopressin analogues, balloon tamponade plus nitrates plus vasopressin analogues, balloon tamponade plus variceal band ligation, portocaval shunt, sclerotherapy plus transjugular intrahepatic portosystemic shunt (TIPS), and sclerotherapy plus vasopressin analogues). We have reported the effect estimates for the primary and secondary outcomes when there was evidence of differences between the interventions against the reference treatment of sclerotherapy, but reported the other results of the primary and secondary outcomes versus the reference treatment of sclerotherapy without the effect estimates when there was no evidence of differences in order to provide a concise summary of the results. Overall, 15.8% of the trial participants who received the reference treatment of sclerotherapy (chosen because this was the commonest treatment compared in the trials) died during the follow-up periods, which ranged from three days to six weeks. Based on moderate-certainty evidence, somatostatin analogues alone had higher mortality than sclerotherapy (OR 1.57, 95% CrI 1.04 to 2.41; network estimate; direct comparison: 4 trials; 353 participants) and vasopressin analogues alone had higher mortality than sclerotherapy (OR 1.70, 95% CrI 1.13 to 2.62; network estimate; direct comparison: 2 trials; 438 participants). None of the trials reported health-related quality of life. Based on low-certainty evidence, a higher proportion of people receiving balloon tamponade plus sclerotherapy had more serious adverse events than those receiving only sclerotherapy (OR 4.23, 95% CrI 1.22 to 17.80; direct estimate; 1 RCT; 60 participants). Based on moderate-certainty evidence, people receiving vasopressin analogues alone and those receiving variceal band ligation had fewer adverse events than those receiving only sclerotherapy (rate ratio 0.59, 95% CrI 0.35 to 0.96; network estimate; direct comparison: 1 RCT; 219 participants; and rate ratio 0.40, 95% CrI 0.21 to 0.74; network estimate; direct comparison: 1 RCT; 77 participants; respectively). Based on low-certainty evidence, the proportion of people who developed symptomatic rebleed was smaller in people who received sclerotherapy plus somatostatin analogues than those receiving only sclerotherapy (OR 0.21, 95% CrI 0.03 to 0.94; direct estimate; 1 RCT; 105 participants). The evidence suggests considerable uncertainty about the effect of the interventions in the remaining comparisons where sclerotherapy was the control intervention.

AUTHORS' CONCLUSIONS

Based on moderate-certainty evidence, somatostatin analogues alone and vasopressin analogues alone (with supportive therapy) probably result in increased mortality, compared to endoscopic sclerotherapy. Based on moderate-certainty evidence, vasopressin analogues alone and band ligation alone probably result in fewer adverse events compared to endoscopic sclerotherapy. Based on low-certainty evidence, balloon tamponade plus sclerotherapy may result in large increases in serious adverse events compared to sclerotherapy. Based on low-certainty evidence, sclerotherapy plus somatostatin analogues may result in large decreases in symptomatic rebleed compared to sclerotherapy. In the remaining comparisons, the evidence indicates considerable uncertainty about the effects of the interventions, compared to sclerotherapy.

Portal hypertension and variceal hemorrhage

Portal hypertension, a major hallmark of cirrhosis, is defined as a portal pressure gradient exceeding 5 mm Hg. In portal hypertension, porto-systemic collaterals decompress the portal circulation and give rise to varices. Successful management of portal hypertension and its complications requires knowledge of the underlying pathophysiology, the pertinent anatomy, and the natural history of the collateral circulation, particularly the gastroesophageal varices.

Octreotide. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in conditions associated with excessive peptide secretion

Octreotide is an analogue of somatostatin. Like endogenous somatostatin, it exerts a potent inhibitory effect on the release of anterior pituitary growth hormone and thyroid-stimulating hormone, and peptides of the gastroenteropancreatic endocrine system, while overcoming some of the shortcomings of exogenously administered somatostatin, namely a short duration of action, a need for intravenous administration and postinfusion rebound hypersecretion of hormone. Clinical studies have shown that octreotide is effective in the treatment of acromegaly and thyrotrophinomas. In comparative trials octreotide was significantly superior to bromocriptine in patients with acromegaly. Octreotide also appears to provide a significant advantage over existing therapies in the management of the carcinoid syndrome and offers considerable therapeutic potential in reversing carcinoid crises which may be life-threatening. Trials in patients with tumours producing vasoactive intestinal peptide demonstrated that octreotide may be an effective first-line choice for this condition, which has usually metastasised and become refractory to traditional symptomatic therapy. In limited studies in patients with high-output secretory diarrhoea, including cryptosporidium-related diarrhoea associated with AIDS and in patients with small bowel fistulas, octreotide has been shown to be effective in reducing stool/fistula output. However, well-designed clinical trials are still required to confirm its long term usefulness in these disorders. Similarly, although the use of octreotide in other conditions such as neonatal hypoglycaemia caused by nesidioblastosis, reactive pancreatitis, insulin-dependent diabetes mellitus, postprandial hypotension and the dumping syndrome has provided encouraging preliminary results, more studies are needed to clarify the place of octreotide in their treatment. Overall, octreotide appears to be well tolerated with the most frequently reported reactions being pain at the site of injection and gastrointestinal symptoms such as abdominal cramps, nausea, bloating, flatulence, diarrhoea and steatorrhoea. These adverse effects usually abate with time. Additionally, octreotide, like endogenous somatostatin, may also result in cholelithiasis, presumably by altering fat absorption and possibly by decreasing motility of the gallbladder. Thus, octreotide represents a new departure from traditional therapies in the treatment of various pathophysiological states associated with excessive peptide production and secretion. It offers a significant advantage over existing therapies in the medical management of patients with acromegaly, thyrotrophinomas, the carcinoid syndrome, tumours producing vasoactive intestinal peptide and severe secretory diarrhoea in whom conventional management options have either become exhausted or have provided suboptimal symptomatic relief.

Somatostatin in portal hypertension

The effect of somatostatin on portal pressure is mediated by splanchnic arterial vasoconstriction which induces a reduction in portal blood flow and pressure. One of the most important characteristics of somatostatin is that its splanchnic effect is not accompanied by major systemic hemodynamic effects. Somatostatin has been used in several controlled trials to test its potential in controlling acute variceal bleeding. The results remain controversial. Different findings in existing clinical trials may derive in part from distinct protocols for somatostatin administration. Published trials suggest that somatostatin may be as effective as vasopressin in the acute management of variceal bleeding. However, since the efficacy of vasopressin has been questioned, a comparison of two potentially ineffective drugs cannot establish definitively the efficacy of somatostatin in controlling variceal bleeding. The most significant finding of the two published studies has been the lower incidence of minor and major complications with somatostatin when compared to vasopressin. Newer trials in progress may shed new light into the potential use of somatostatin for the treatment of variceal bleeding.

Secretin and somatostatin in the treatment of upper gastrointestinal haemorrhage

Secretin inhibits gastric secretion of acid and gastrin in dog and a physiological role of secretin as an enterogastrone has been suggested in this species. In man there are diverging results concerning the effect of secretin on gastric secretion. Secretin has been used in patients with upper gastrointestinal bleeding and positive results have been reported, but the patients included in these studies cannot be considered as massive bleeders. Until now no double-blind study comparing secretin with placebo has been reported. Somatostatin decreases splanchnic blood flow and gastric secretion in man. Somatostatin seems to be effective in achieving initial haemostasis in patients with bleeding oesophageal varices. The peptide has also been shown to stop severe and persistent peptic ulcer haemorrhage and to stop bleeding in patients treated with steroidal and non-steroidal anti-inflammatory drugs. In one double-blind trial in patients with upper gastrointestinal bleeding, somatostatin had no effect on either the number of emergency operations or the number of rebleedings. In another double blind study, when somatostatin was compared with placebo in patients with massive upper gastrointestinal bleeding, the peptide reduced the number of emergency operations. In conclusion, most studies show positive effects of somatostatin on variceal and peptic ulcer haemorrhage.

Effects of a somatostatin analogue SMS 201-995 on hepatic haemodynamics in the pig and on intravariceal pressure in man

The effects of a somatostatin analogue, SMS 201-995, on hepatic haemodynamics in the pig and on intravariceal pressure in man were studied. An infusion of 250 micrograms/h SMS 201-995 significantly reduced portal pressure, portal venous flow and hepatic artery flow in the pig. These changes in hepatic haemodynamics were accompanied by a reduction in cardiac output, a reflex slowing of the heart and an increase in arterial blood pressure. Splanchnic vascular resistance was increased following SMS 201-995 administration but hepatic vascular resistance remained unchanged. Administration of 50 micrograms SMS 201-995 reduced the intravariceal pressure from 27.4 +/- 2.5 to 15.8 +/- 2.1 mmHg in 9 patients with cirrhosis and portal hypertension. Administration of 50 micrograms SMS 201-995 also reduced portal pressure from 29 to 22 mmHg in a patient undergoing an elective portacaval shunt. These results suggest that SMS 201-995 may be of value in the control of bleeding oesophageal varices. Furthermore, because of its prolonged duration of action SMS 201-995 may be useful in the long term management of portal hypertension in patients with cirrhosis.