Amphetamine-related presentations to an inner-city tertiary emergency department: a prospective evaluation

The illicit use of amphetamines in the community as recreational drugs and drugs of addiction is increasing.1 Amphetamine intoxication appears to be a common reason for presentation to emergency departments (EDs), but, to our knowledge, there are no published data describing the prevalence and characteristics of amphetamine-related presentations to EDs. Our aim was to describe these features in the setting of the ED at the Royal Perth Hospital (RPH), Western Australia.

A prospective observational cohort study was undertaken over a 3-month period from 3 August to 2 November 2005 at the RPH, an adult, inner-city, tertiary referral hospital. The ED has an annual census of about 53 000, with an admission rate of 42%.

A mandatory diagnostic prompt in the ED computerised data information system (inserted for the purpose of our study) ensured that each presenting patient was assessed for amphetamine use. Doctors were asked, “Is this presentation related to amphetamines?” The possible responses were “yes”, “no” or “unsure”. Amphetamine-related problems were considered to be any presenting complaint directly related to recent amphetamine use. This included symptoms of acute intoxication, withdrawal, psychiatric illness, and complications of intravenous drug use (such as infection). Amphetamine use was elicited from the history recorded at triage or during medical assessment. Urinary amphetamine drug screens were not performed, as this did not comply with normal clinical practice at the RPH. Moreover, patients with delayed sequelae of amphetamine use would not have been detected with urinary screening.

Medical staff prospectively completed a preformatted data sheet for patients identified clinically as having presentations related to amphetamine use. Medical records for patients for whom doctors were unsure about amphetamine use were recalled and examined by a single unblinded investigator (S D G). The data recorded included demographic data, drug use history, physiological data, management and disposition.

Over the 3-month period, there were 13 125 presentations to the ED, of which 156 (1.2%) were judged clinically to be causally related to amphetamine use (mean, 12 presentations a week; annual estimate, 624). Fifteen patients presented twice during the study period for amphetamine-related problems, and one patient presented three times. There were no deaths.

Statistics on demographic features, ED presentations, amphetamine use and associated conditions are presented in Box 1. Presentations occurred on every day of the week with relatively similar frequency. Presentations were of high acuity, with 104 (66.7%) being rated 1, 2 or 3 on the Australasian Triage Scale (meaning that the patient should be seen by a doctor within 0, 10 or 30 minutes, respectively).2

The most common reasons for presentation are outlined in Box 2. Many patients had associated psychiatric illness (Box 1), and 56 (35.9%) reported a drug dependence. Eighty-nine (57.1%) said they used amphetamines at least weekly, and 53 (34.0%) used marijuana on a weekly basis.

On initial observation, 66 patients (42.3%) were tachycardic (heart rate [HR] ≥ 100 beats/min) and 10 (6.4%) were hypertensive (systolic blood pressure ≥ 160 mmHg). Of the patients who were tachycardic on presentation, 30 (45.5%) needed benzodiazepine sedation in the ED.

Compared with patients who did not have tachycardia, the OR for patients with an initial HR ≥ 100 beats/min requiring sedation was 2.9 (95% CI, 1.5–5.8; P = 0.002). The mean initial HR for patients not requiring sedation was 90 beats/min, compared with 108 beats/min for patients who received sedation (mean difference, 18 beats/min; 95% CI, 9–27 beats/min; P < 0.001).

In total, 50 patients (32.1%) required sedation (intravenous or oral benzodiazepines) for agitation. In the first 4 hours, the maximum parenteral dose administered to any individual patient was 65 mg diazepam intravenously or 40 mg midazolam intramuscularly.

Baseline investigations included an electrocardiogram in 78 patients (50.0%) and blood tests for urea and electrolytes in 91 (58.3%). Fifteen (9.6%) required a cranial computed tomography scan to investigate a headache or seizure. Fifty-eight patients (37.2%) received psychiatric review by the psychiatric liaison service in the ED.

Of the 31 patients admitted to the ED observation ward, 20 (64.5%) had diagnoses of amphetamine intoxication requiring ongoing sedation and observation. Three patients admitted to the ED observation ward had chest pain, and three were suffering from polysubstance overdose. Three of the 12 patients admitted to a psychiatric ward required police escort to a locked ward. Ten of the 15 patients admitted to a general ward were diagnosed with cellulitis or abscess following intravenous drug use.

Three patients, who had all used amphetamines intravenously, were admitted to the intensive care unit: a 21-year-old man had experienced a prolonged seizure; a 33-year-old woman had infective endocarditis complicated by two cerebral embolic infarcts; and a 26-year-old man with severe sympathomimetic syndrome subsequently developed aspiration pneumonia and encephalopathy. A 36-year-old man was admitted to the coronary care unit with chest pain, which was subsequently diagnosed as coronary artery spasm.

Review of the patients’ medical records revealed that 71 (45.5%) had had previous amphetamine-related presentations to the RPH ED. Seventeen (10.9%) stated that they had attended the ED with a heroin overdose.

Amphetamines are a group of central nervous system stimulants that include amphetamine and amphetamine-related derivatives known as “designer” amphetamines. These designer drugs are produced, with varying purities, in clandestine laboratories.3 Common street names for the drugs are listed in Box 3.7 Amphetamines may be injected, ingested, insufflated (snorted) or smoked. They enhance release and block reuptake of catecholamines, resulting in central nervous system stimulation and peripheral sympathomimetic effects. The clinical effects of acute intoxication are summarised in Box 4.8,9 Deaths have occurred as the result of sympathomimetic syndrome (hyperpyrexia, tachycardia and hypertension), seizures, intracerebral haemorrhage, myocardial infarction, cardiac arrhythmias and aortic dissection.

Our results highlight the impact of amphetamines on the health system, especially EDs. A small number of retrospective studies from Hawaii,10 California11 and London12 suggest amphetamine use is associated with increased use of hospital resources, but to date there have been no Australian studies in this area.

We found that amphetamine-related presentations are of high acuity, result in prolonged length of stay in the ED and consume considerable resources. A third of patients required sedation, which correlates with a high prehospital, nursing, medical and security load to manage these patients safely. Further contributing to the impact are the high rates of repeat attendance and the large proportion of patients with underlying psychiatric illness and a history of drug dependence. Amphetamine use is associated with violence, antisocial behaviour and risk-taking.5 Twenty per cent of all amphetamine-related presentations to our ED involved the police at some stage. Also of great concern is emerging evidence of serious long-term effects, including depression, anxiety, psychosis and memory disturbance.13-16

There were limitations to our study. The main issue was the difficulty of capturing all patients with amphetamine-related presentations. As routine drug screens were not performed, we relied on clinical assessment. Some patients (such as multi-trauma patients) who were unable to give an adequate history or who were not questioned on their drug use history may have been missed. Although medical staff were required to complete a preformatted data sheet and were prompted to consider amphetamine use, there was variable compliance with this. If patients had missing information, their charts were recalled for review and data were retrospectively obtained.

Another limitation of our study was its relatively short duration. Over the 3-month period, the full spectrum of amphetamine-related illnesses was not observed. It is well recognised that amphetamine use can be associated with acute myocardial infarction, subarachnoid haemorrhage, aortic dissection and acute rhabdomyolysis.8,13 Although there are about six documented cases of this type at the RPH each year, there were no presentations as a result of these severe complications during the study period.

In summary, we found that amphetamine-related presentations comprised 1.2% of all ED attendances and had a major impact on the ED. Patients with acute amphetamine intoxication are often agitated and aggressive, require extensive resources such as sedation, and frequently re-attend. With increasing availability and use of amphetamines, the burden on emergency services will continue to grow.