Early indicators of prognosis in fulminant hepatic failure

The successful use of orthotopic liver transplantation in fulminant hepatic failure has created a need for early prognostic indicators to select the patients most likely to benefit at a time when liver transplantation is still feasible. Univariate and multivariate analysis was performed on 588 patients with acute liver failure managed medically during 1973-1985, to identify the factors most likely to indicate a poor prognosis. In acetaminophen-induced fulminant hepatic failure, survival correlated with arterial blood pH, peak prothrombin time, and serum creatinine--a pH less than 7.30, prothrombin time greater than 100 s, and creatinine greater than 300 mumol/L indicating a poor prognosis. In patients with viral hepatitis and drug reactions three static variables [etiology (non A, non B hepatitis or drug reactions), age less than 11 and greater than 40 yr, duration of jaundice before the onset of encephalopathy greater than 7 days] and two dynamic variables (serum bilirubin greater than 300 mumol/L and prothrombin time greater than 50 s) indicated a poor prognosis. The value of these indicators in determining outcome was tested retrospectively in a further 175 patients admitted during 1986-1987, leading to the construction of models for the selection of patients for liver transplantation.

Acetaminophen-induced acute liver failure: results of a United States multicenter, prospective study

Severe acetaminophen hepatotoxicity frequently leads to acute liver failure (ALF). We determined the incidence, risk factors, and outcomes of acetaminophen-induced ALF at 22 tertiary care centers in the United States. Detailed prospective data were gathered on 662 consecutive patients over a 6-year period fulfilling standard criteria for ALF (coagulopathy and encephalopathy), from which 275 (42%) were determined to result from acetaminophen liver injury. The annual percentage of acetaminophen-related ALF rose during the study from 28% in 1998 to 51% in 2003. Median dose ingested was 24 g (equivalent to 48 extra-strength tablets). Unintentional overdoses accounted for 131 (48%) cases, intentional (suicide attempts) 122 (44%), and 22 (8%) were of unknown intent. In the unintentional group, 38% took two or more acetaminophen preparations simultaneously, and 63% used narcotic-containing compounds. Eighty-one percent of unintentional patients reported taking acetaminophen and/or other analgesics for acute or chronic pain syndromes. Overall, 178 subjects (65%) survived, 74 (27%) died without transplantation, and 23 subjects (8%) underwent liver transplantation; 71% were alive at 3 weeks. Transplant-free survival rate and rate of liver transplantation were similar between intentional and unintentional groups. In conclusion, acetaminophen hepatotoxicity far exceeds other causes of acute liver failure in the United States. Susceptible patients have concomitant depression, chronic pain, alcohol or narcotic use, and/or take several preparations simultaneously. Education of patients, physicians, and pharmacies to limit high-risk use settings is recommended.

Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. Analysis of the national multicenter study (1976 to 1985)

During the investigational use of oral N-acetylcysteine as an antidote for poisoning with acetaminophen, 11,195 cases of suspected acetaminophen overdose were reported. We describe the outcomes of 2540 patients with acetaminophen ingestions treated with a loading dose of 140 mg of oral N-acetylcysteine per kilogram of body weight, followed four hours later by 70 mg per kilogram given every four hours for an additional 17 doses. Patients were categorized for analysis on the basis of initial plasma acetaminophen concentrations and the interval between ingestion and treatment. Hepatotoxicity developed in 6.1 percent of patients at probable risk when N-acetylcysteine was started within 10 hours of acetaminophen ingestion and in 26.4 percent of such patients when therapy was begun 10 to 24 hours after ingestion. Among patients at high risk who were treated 16 to 24 hours after an acetaminophen overdose, hepatotoxicity developed in 41 percent--a rate lower than that among historical controls. When given within eight hours of acetaminophen ingestion, N-acetylcysteine was protective regardless of the initial plasma acetaminophen concentration. There was no difference in outcome whether N-acetylcysteine was started zero to four or four to eight hours after ingestion, but efficacy decreased with further delay. There were 11 deaths among the 2540 patients (0.43 percent); in the nine fatal cases in which aminotransferase was measured before treatment, values were elevated before N-acetylcysteine was started. No deaths were clearly caused by acetaminophen among patients in whom N-acetylcysteine therapy was begun within 16 hours. We conclude that N-acetylcysteine treatment should be started within eight hours of an acetaminophen overdose, but that treatment is still indicated at least as late as 24 hours after ingestion. On the basis of available data, the 72-hour regimen of oral N-acetylcysteine is as effective as the 20-hour intravenous regimen described previously, and it may be superior when treatment is delayed.

EASL Clinical Practical Guidelines on the management of acute (fulminant) liver failure

The term acute liver failure (ALF) is frequently applied as a generic expression to describe patients presenting with or developing an acute episode of liver dysfunction. In the context of hepatological practice, however, ALF refers to a highly specific and rare syndrome, characterised by an acute abnormality of liver blood tests in an individual without underlying chronic liver disease. The disease process is associated with development of a coagulopathy of liver aetiology, and clinically apparent altered level of consciousness due to hepatic encephalopathy. Several important measures are immediately necessary when the patient presents for medical attention. These, as well as additional clinical procedures will be the subject of these clinical practice guidelines.

Intravenous N-acetylcystine: the treatment of choice for paracetamol poisoning

One hundred cases of severe paracetamol poisoning were treated with intravenous N-acetylcysteine (acetyl-cysteine). There was virtually complete protection against liver damage in 40 patients treated within eight hours after ingestion (mean maximum serum alanine transaminase activity 27 IU/1). Only one out of 62 patients treated within 10 hours developed severe liver damage compared with 33 out of 57 patients (58%) studied retrospectively who received supportive treatment alone. Early treatment and acetylcysteine also prevented renal impairment and death. The critical ingestion-treatment interval for complete protection against severe liver damage was eight hours. Efficacy diminished progressively thereafter, and treatment after 15 hours was completely ineffective. Intravenous acetylcysteine was more effective than cysteamine and methionine and noticeably free of adverse effects. It is the treatment of choice for paracetamol poisoning.

Acute liver failure

Acute liver failure is a rare and severe consequence of abrupt hepatocyte injury, and can evolve over days or weeks to a lethal outcome. A variety of insults to liver cells result in a consistent pattern of rapid-onset elevation of aminotransferases, altered mentation, and disturbed coagulation. The absence of existing liver disease distinguishes acute liver failure from decompensated cirrhosis or acute-on-chronic liver failure. Causes of acute liver failure include paracetamol toxicity, hepatic ischaemia, viral and autoimmune hepatitis, and drug-induced liver injury from prescription drugs, and herbal and dietary supplements. Diagnosis requires careful review of medications taken, and serological testing for possible viral exposure. Because of its rarity, acute liver failure has not been studied in large, randomised trials, and most treatment recommendations represent expert opinion. Improvements in management have resulted in lower mortality, although liver transplantation, used in nearly 30% of patients with acute liver failure, still provides a life-saving alternative to medical management.

N-Acetylcysteine--a safe antidote for cysteine/glutathione deficiency

Glutathione (GSH) deficiency is associated with numerous pathological conditions. Administration of N-acetylcysteine (NAC), a cysteine prodrug, replenishes intracellular GSH levels. NAC, best known for its ability to counter acetaminophen toxicity, is a safe, well-tolerated antidote for cysteine/GSH deficiency. NAC has been used successfully to treat GSH deficiency in a wide range of infections, genetic defects and metabolic disorders, including HIV infection and COPD. Over two-thirds of 46 placebo-controlled clinical trials with orally administered NAC have indicated beneficial effects of NAC measured either as trial endpoints or as general measures of improvement in quality of life and well-being of the patients.

The systemic inflammatory response syndrome in acute liver failure

The systemic inflammatory response syndrome (SIRS) in acute liver failure (ALF), in which infection is common, has not been studied. In this study, SIRS components were recorded on admission and during episodes of infection, in 887 ALF patients admitted to a single center during an 11-year period. Overall, 504 (56.8%) patients manifested a SIRS during their illness, with a maximum of 1, 2, and 3 concurrent SIRS components in 166, 238, and 100 patients, respectively. In 353 (39.8%) patients who did not become infected, a SIRS on admission was associated with a more critical illness, subsequent worsening of encephalopathy, and death. Infected patients more often developed a SIRS and one of greater magnitude. The magnitude of the SIRS in 273 patients with bacterial infection correlated with mortality, being 16.7%, 28.4%, 41.2%, and 64.7% in patients with 0, 1, 2, and 3 maximum concurrent SIRS components, respectively. Similar correlations with mortality were seen for SIRS associated with fungal infection, bacteremia, and bacterial chest infection. Fifty-nine percent of patients with severe sepsis died, as did 98% of those with septic shock. A significant association was found between progressive encephalopathy and infection. Infected patients with progressive encephalopathy manifested more SIRS components than other infected patients. For patients with a SIRS, the proportions of infected and noninfected patients manifesting worsening encephalopathy were similar. In ALF, the SIRS, whether or not precipitated by infection, appears to be implicated in the progression of encephalopathy, reducing the chances of transplantation and conferring a poorer prognosis.

The canals of Hering and hepatic stem cells in humans

Small, extraportal, hepatic parenchymal cells, positive for biliary-type cytokeratins, may represent hepatic stem cells, canals of Hering (CoH), and/or ductal plate remnants. We evaluated these cells 3 dimensionally in normal human liver and massive necrosis. Tissues from normal human livers and from 1 liver with acetaminophen-induced massive necrosis were serially sectioned, immunostained for cytokeratin 19 (CK19), and sequentially photographed. Images were examined to determine 3-dimensional relationships among CK19-positive cells. Immunostains for other hepatocyte and progenitor cell markers were examined. In normal livers, intraparenchymal CK19-positive cells lined up as linear arrays in sequential levels. One hundred of 106 (94.3%) defined, complete arrays within levels examined, most having 1 terminus at a bile duct, the other in the lobule, beyond the limiting plate. In massive necrosis, there were 767 individual CK19-positive cells or clusters around a single portal tract, 747 (97.4%) of which were spatially related forming arborizing networks connected to the interlobular bile duct by single tributaries. C-kit was positive in normal CoH. CK19 co-expressed with HepPar1, c-kit, and alpha-fetoprotein (AFP) in parenchymal cells in massive necrosis. Small, extraportal, biliary-type parenchymal cells represent cross-sections of the CoH that radiate from the portal tract, usually extending past the limiting plate into the proximate third of the hepatic lobule. The 3-dimensional structure of ductular reactions in massive necrosis suggests that these reactions are proliferations of the cells lining the CoH. Therefore, the CoH consist of, or harbor, facultative hepatic stem cells in humans.

Controlled trials of charcoal hemoperfusion and prognostic factors in fulminant hepatic failure

One hundred thirty-seven patients with fulminant hepatic failure were entered into two controlled trials of charcoal hemoperfusion carried out concurrently. In trial A, 75 patients with grade 3 encephalopathy were randomized to receive 5 or 10 h of hemoperfusion daily. Overall survival rates for the two groups were similar (51.3% vs. 50.0%) as was the frequency of major complications including cerebral edema and renal failure. In trial B, in which 62 patients with established grade 4 encephalopathy on admission were randomized to a no-perfusion group or to have 10 h of hemoperfusion daily, overall survival rates for the two groups were again similar (39.3% and 34.5%, respectively). There was in both trials a significant relationship between survival and etiology quite independent of the use or duration of hemoperfusion. Thus, percentage survival for the acetaminophen-overdose cases was 52.9%, for hepatitis A 66.7%, for hepatitis B 38.9%, for presumed non-A, non-B hepatitis 20%, and for halothane or drug reaction 12.5%. Within the etiologic subgroups survival was also influenced by the three major complications that developed, being inversely related to their frequency and combination, except in the non-A, non-B hepatitis and halothane or drug reaction subgroups, which had a high mortality throughout. In the latter cases particularly, orthotopic liver transplantation merits early consideration and in the group with better "intrinsic" survival (acetaminophen, hepatitis A and B) intensive management of complications (rather than charcoal hemoperfusion) would appear to be of major importance.

Acute liver necrosis following overdose of paracetamol

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Improvement by acetylcysteine of hemodynamics and oxygen transport in fulminant hepatic failure

BACKGROUND

When administered early after an overdose of acetaminophen, intravenous acetylcysteine prevents hepatic necrosis by replenishing reduced stores of glutathione. How acetylcysteine improves the survival of patients with established liver damage induced by acetaminophen, however, is unknown. This study was undertaken to determine whether the beneficial effect of acetylcysteine under such circumstances could be due to enhancement of oxygen delivery and consumption.

METHODS

We studied the effect of acetylcysteine on systemic hemodynamics and oxygen transport in 12 patients with acetaminophen-induced fulminant hepatic failure and 8 patients with acute liver failure from other causes. The acetylcysteine was given in a dose of 150 mg per kilogram of body weight in 250 ml of 5 percent dextrose over a period of 15 minutes and then in a dose of 50 mg per kilogram in 500 ml of 5 percent dextrose over a period of 4 hours; measurements were made before treatment began and after 30 minutes of the regimen.

RESULTS

In the patients with acetaminophen-induced liver failure, the infusion of acetylcysteine resulted in an increase in mean oxygen delivery from 856 to 975 ml per minute per square meter of body-surface area (P = 0.0036), due to an increase in the cardiac index from 5.6 to 6.7 liters per minute per square meter (P = 0.0021). Mean arterial pressure rose from 88 to 95 mm Hg (P = 0.0054) despite a decrease in systemic vascular resistance from 1296 to 1113 dyn.sec.cm-5 per square meter (P = 0.027). There was an increase in oxygen consumption from 127 to 184 ml per minute per square meter (P = 0.0007) associated with an increase in the oxygen-extraction ratio from 16 to 21 percent (P = 0.022). The effects in the patients with acute liver failure from other causes were similar.

CONCLUSIONS

The increase in oxygen delivery and consumption in response to acetylcysteine may account for its beneficial effect on survival in patients with fulminant hepatic failure induced by acetaminophen.

Acetaminophen and the U.S. Acute Liver Failure Study Group: lowering the risks of hepatic failure

Acetaminophen overdose is the leading cause for calls to Poison Control Centers (>100,000/year) and accounts for more than 56,000 emergency room visits, 2,600 hospitalizations, and an estimated 458 deaths due to acute liver failure each year. Data from the U.S. Acute Liver Failure Study Group registry of more than 700 patients with acute liver failure across the United States implicates acetaminophen poisoning in nearly 50% of all acute liver failure in this country. Available in many single or combination products, acetaminophen produces more than 1 billion US dollars in annual sales for Tylenol products alone. It is heavily marketed for its safety compared to nonsteroidal analgesics. By enabling self-diagnosis and treatment of minor aches and pains, its benefits are said by the Food and Drug Administration to outweigh its risks. It still must be asked: Is this amount of injury and death really acceptable for an over-the-counter pain reliever?

Acetaminophen hepatotoxicity

Acetaminophen is a commonly used antipyretic and analgesic agent. It is safe when taken at therapeutic doses; however, overdose can lead to serious and even fatal hepatotoxicity. The initial metabolic and biochemical events leading to toxicity have been well described, but the precise mechanism of cell injury and death is unknown. Prompt recognition of overdose, aggressive management, and administration of N-acetylcysteine can minimize hepatotoxicity and prevent liver failure and death. Liver transplantation can be lifesaving for those who develop acute liver failure.

Clinical pharmacokinetics of paracetamol

In therapeutic doses paracetamol is a safe analgesic, but in overdosage it can cause severe hepatic necrosis. Following oral administration it is rapidly absorbed from the gastrointestinal tract, its systemic bioavailability being dose-dependent and ranging from 70 to 90%. Its rate of oral absorption is predominantly dependent on the rate of gastric emptying, being delayed by food, propantheline, pethidine and diamorphine and enhanced by metoclopramide. Paracetamol is also well absorbed from the rectum. It distributes rapidly and evenly throughout most tissues and fluids and has a volume of distribution of approximately 0.9L/kg. 10 to 20% of the drug is bound to red blood cells. Paracetamol is extensively metabolised (predominantly in the liver), the major metabolites being the sulphate and glucuronide conjugates. A minor fraction of drug is converted to a highly reactive alkylating metabolite which is inactivated with reduced glutathione and excreted in the urine as cysteine and mercapturic acid conjugates. Large doses of paracetamol (overdoses) cause acute hepatic necrosis as a result of depletion of glutathione and of binding of the excess reactive metabolite to vital cell constituents. This damage can be prevented by the early administration of sulfhydryl compounds such as methionine and N-acetylcysteine. In healthy subjects 85 to 95% of a therapeutic dose is excreted in the urine within 24 hours with about 4, 55, 30, 4 and 4% appearing as unchanged paracetamol and its glucuronide, sulphate, mercapturic acid and cysteine conjugates, respectively. The plasma half-life in such subjects ranges from 1.9 to 2.5 hours and the total body clearance from 4.5 to 5.5 ml/kg/min. Age has little effect on the plasma half-life, which is shortened in patients taking anticonvulsants. The plasma half-life is usually normal in patients with mild chronic liver disease, but its prolonged in those with decompensated liver disease.

Treatment of paracetamol (acetaminophen) poisoning with N-acetylcysteine

Fifteen patients with paracetamol (acetaminophen) poisoning were treated with intravenous N-acetylcystein (300 mg/kg given over 20 h). Mean admission and 4 h plasma-paracetamol concentrations were 262 and 369 microgram/ml, respectively. Liver-function tests remained normal or were only slightly disturbed in 11 of 12 patients treated within 10 h of paracetamol ingestion. Severe liver damage developed in the other patient and in the three in whom treatment was started more than 10 h after paracetamol ingestion. In contrast to cysteamine, N-acetylcysteine was very well tolerated and has the advantage of being available as a pharmaceutical preparation in a 20% sterile solution.

The role of oxidant stress and reactive nitrogen species in acetaminophen hepatotoxicity

Acetaminophen (AAP) overdose can cause severe hepatotoxicity and even liver failure in experimental animals and humans. Despite substantial efforts over the last 30 years, the mechanism of AAP-induced liver cell injury is still not completely understood. It is widely accepted that the injury process is initiated by the metabolism of AAP to a reactive metabolite, which first depletes glutathione and then binds to cellular proteins including a number of mitochondrial proteins. One consequence of this process may be the observed inhibition of mitochondrial respiration, ATP depletion and mitochondrial oxidant stress. In the presence of sufficient vitamin E, reactive oxygen formation does not induce severe lipid peroxidation but the superoxide reacts with nitric oxide to form peroxynitrite, a powerful oxidant and nitrating agent. Peroxynitrite can modify cellular macromolecules and may aggravate mitochondrial dysfunction and ATP depletion leading to cellular oncotic necrosis in hepatocytes and sinusoidal endothelial cells. Thus, we hypothesize that reactive metabolite formation and protein binding initiate the injury process, which may be then propagated and amplified by mitochondrial dysfunction and peroxynitrite formation. This concept also reconciles many of the controversial findings of the past and provides a viable hypothesis for the mechanism of hepatocellular injury after AAP overdose.

Intravenous acetylcysteine in paracetamol induced fulminant hepatic failure: a prospective controlled trial

OBJECTIVE

To see whether intravenous acetylcysteine would improve outcome in patients with fulminant hepatic failure after paracetamol overdose.

DESIGN

A prospective randomised controlled study.

SETTING

The Institute of Liver Studies, King's College Hospital, London.

PATIENTS

50 consecutive patients (21 male) aged 16-60 with fulminant hepatic failure after paracetamol overdose who had not previously received acetylcysteine.

INTERVENTIONS

Conventional intensive liver care plus either acetylcysteine (25 patients) in the same dose regimen as used early after a paracetamol overdose, except that the infusion was continued until recovery from encephalopathy or death, or an equivalent volume of 5% dextrose (25 patients).

MAIN OUTCOME MEASURES

Survival; incidence of cerebral oedema, renal failure, and hypotension requiring inotropic support; liver function as assessed by prolongation of the prothrombin time; and degree of encephalopathy.

RESULTS

The rate of survival was significantly higher in the acetylcysteine treated group than in the controls (48% (12/25 patients) v 20% (5/25); p = 0.037, 95% confidence interval for difference in proportions surviving 3% to 53%). Acetylcysteine treated patients had a lower incidence of cerebral oedema (40% (10/25) v 68% (17/25); p = 0.047, 95% confidence interval for difference in incidence 2% to 54%), and fewer developed hypotension requiring inotropic support (48% (12/25) v 80% (20/25); p = 0.018, 95% confidence interval 7% to 57%). Rates of deterioration and recovery of liver function, however, were similar in the two groups. No adverse reactions to acetylcysteine were seen.

CONCLUSIONS

Acetylcysteine is safe and effective in fulminant hepatic failure after paracetamol overdose.

Etiology and outcome for 295 patients with acute liver failure in the United States

Little information is available on acute liver failure (ALF) in the United States. We gathered demographic data retrospectively for a 2-year period from July 1994 to June 1996 on all cases of ALF from 13 hospitals (12 liver transplant centers). Data on the patients included age, hepatic coma grade on admission, presumed cause, transplantation, and outcome. Among 295 patients, 74 (25%) survived spontaneously, 121 (41%) underwent transplantation, and 99 (34%) died without undergoing transplantation. Ninety-two of 121 patients (76%) survived 1 year after transplantation. Acetaminophen overdose was the most frequent cause (60 patients; 20%), followed by cryptogenic/non A non B non C (NANBNC; 15%), idiosyncratic drug reactions (12%), hepatitis B (10%), and hepatitis A (7%). Spontaneous survival rates were highest for patients with acetaminophen overdose (57%) and hepatitis A (40%) and lowest for those with Wilson's disease (no survivors of 18 patients). The transplantation rate was highest for Wilson's disease (17 of 18 patients; 94%) and lowest for autoimmune hepatitis (29%) and acetaminophen overdose (12%). Age did not differ between survivors and nonsurvivors, perhaps reflecting a selection bias for patients transferred to liver transplant centers. Coma grade on admission was not a significant determinant of outcome, but showed a trend toward affecting both survival and transplantation rate. These findings on retrospectively studied patients from the United States differ from those previously gathered in the United Kingdom and France, highlighting the need for further study of trends in each country.

Acetylcysteine for acetaminophen poisoning

A 25-year-old man presents to the emergency department with a toothache. During the evaluation, the physician determines that the patient has been taking large doses of over-the-counter acetaminophen along with an acetaminophen–hydrocodone product for the past 5 days. His daily dose of acetaminophen has been 12 g per day (maximum recommended dose, 4 g per day). He has no other medical problems and typically consumes two beers a day. The patient has no symptoms beyond his toothache, is not icteric, and has no hepatomegaly or right-upper-quadrant tenderness. His serum acetaminophen concentration 8 hours after the most recent dose is undetectable. His serum alanine aminotransferase concentration is 75 IU per liter, his serum bilirubin concentration is 1.2 mg per deciliter (20.5 μmol per liter), and his international normalized ratio (INR) is 1.1. The emergency department physician contacts the regional poison-control center, which recommends treatment with acetylcysteine.

Acetaminophen (APAP) hepatotoxicity-Isn't it time for APAP to go away?

Acetaminophen (APAP) is the most commonly used drug for the treatment of pain and fever around the world. At the same time, APAP can cause dose-related hepatocellular necrosis, responsible for nearly 500 deaths annually in the United States (US) alone, as well as 100,000 calls to US Poison Control Centers, 50,000 emergency room visits and 10,000 hospitalisations per year. As an over-the-counter and prescription product (with opioids), APAP toxicity dwarfs all other prescription drugs as a cause of acute liver failure in the US and Europe, but it is not regulated in any significant way. In this review the ongoing controversy surrounding the proper role for this ubiquitous pain reliever: its history, pathogenesis, clinical challenges in recognition and management, and current regulatory status are highlighted. A new solution to a 50-year-old problem is proposed.

Acetaminophen overdose. 662 cases with evaluation of oral acetylcysteine treatment

Six hundred sixty-two consecutive patients with acetaminophen overdoses were evaluated. Those at risk on the basis of their acetaminophen blood levels, as plotted on the study nomogram, were treated with oral acetylcysteine. Statistically significant differences in severity of hepatic toxicity were observed between patients treated within 16 hours after ingestion and those treated between 16 and 24 hours after ingestion. No deaths occurred among patients treated within 24 hours of ingestion, except for one patient who was an alleged gunshot homicide. Seven percent of patients with plasma acetaminophen levels in the potentially toxic range and treated with acetylcysteine within ten hours of ingestion showed transient SGOT level elevations, whereas 29% of those treated between ten and 16 hours after ingestion and 62% of those treated between 16 and 24 hours after ingestion showed such transient toxicity. No consistent difference in hepatotoxicity could be demonstrated between those patients with a history of chronic alcohol use and those patients with no history of chronic alcohol use. Acute alcohol use resulted in less severe toxic reactions than in those patients without acute alcohol use.

Acetaminophen toxicity in an urban county hospital

BACKGROUND

The prevalence and characteristics of acetaminophen-associated liver injury in hospitalized patients are not well defined.

METHODS

We identified patients hospitalized for excessive acetaminophen ingestion at an urban county hospital over a 40-month period (1992 to 1995) and reviewed their medical records to determine the incidence and clinical features of the ingestions and their outcomes.

RESULTS

Of the 71 patients studied, 50 were classified as having taken acetaminophen during suicide attempts and 21 as having accidentally poisoned themselves while attempting to relieve pain. The suicidal patients had ingested almost twice as much acetaminophen as those in the accidental-overdose group (median, 20 vs. 12 g; P=0.009). Among the patients for whom data were available, 63 percent of those in the accidental-overdose group and 25 percent of those in the suicidal group had chronic alcohol abuse (P=0.009). The patients in the accidental-overdose group more often had severe liver necrosis (aminotransferase levels, >3500 IU per liter; 52 percent vs. 14 percent; P=0.002), and were more likely to have hepatic coma (33 percent vs. 6 percent, P=0.006). There were four deaths (19 percent) in the accidental-overdose group and one (2 percent) in the suicidal group (P=0.04). Five patients -- three in the accidental-overdose group and two in the suicidal group -- had ingested 4 g of acetaminophen or less. Acetaminophen ingestion accounted for 12 percent of all patients hospitalized with overdoses (71 of 589) and 40 percent of patients with acute liver failure (10 of 25) during the study period.

CONCLUSIONS

In an urban county hospital, patients hospitalized with acetaminophen toxicity related to accidental misuse had higher rates of morbidity and mortality than those who attempted suicide, even though the latter had taken more acetaminophen. A higher frequency of chronic alcohol abuse among the patients with accidental overdoses may be one explanation.