Emergency Medicine

(2001)

13

, 37–42

Blackwell Science Asia

Original Research

Impact of a toxicology service on a metropolitan teaching hospital

Victor Lee,

1

J Fergus Kerr,

1

George Braitberg,

1

William J Louis,

2

Chris J O’Callaghan,

2

Albert G Frauman

2

and M Laurence Mashford

2

1

Department of Emergency Medicine, Austin & Repatriation Medical Centre, and

2

Clinical Pharmacology & Therapeutics Unit, Department of Medicine, University of Melbourne, Austin

& Repatriation Medical Centre, Melbourne, Victoria, Australia

Abstract

Objective:

To evaluate the impact of a toxicology service on a major metropolitan teaching hospital.

Method:

A descriptive comparative study of all patients presenting with poisoning or suspectedpoisoning 12 months before and after the commencement of a toxicology service. Data onlength of stay in the emergency department, disposition, length of stay of admitted patientsand substance(s) involved were examined.

Results:

A total of 1316 poisoned patients were studied. There was a statistically significant increasein self-poisonings from 612 to 704 (

P

= 0.002) and in the number of admissions from 113to 192 (

P

< 0.05). There was no significant change in emergency department length of stay.The average length of stay for patients admitted under the care of the toxicology servicedecreased, especially for complicated patients.

Conclusion:

In the first 12 months of operation the toxicology service treated more patients than the 12-month period prior to commencement, achieving a decrease in average length of stay for thosepatients admitted to the service. The emergency department length of stay was not altered.We surmise that by decreasing average length of stay for the patients under the care of thetoxicology service, the net increase in the general pool of unoccupied beds improves bedaccess for all emergency department patients.

Key words:

length of stay, self-poisoning, toxicology service.

Introduction

Currently, it is estimated that deliberate self-poisoningsaccount for 1–5% of all general hospital admissions.

1

Although this figure does not include self-poisonings seenin the emergency department (ED) who are not admitted,together these two groups constitute a significant work-load on the ED.

Correspondence: Dr Victor Lee, Registrar, Department of Emergency Medicine, Austin & Repatriation Medical Centre, Studley Rd, Heidelberg, Vic. 3084, Australia. Email: vlee@netspace.net.au

Victor Lee, MB BS, Registrar, Department of Emergency Medicine; J Fergus Kerr, MB BS, FACEM, MPH, Clinical Toxicologist/Emergency Physician; George Braitberg, MB BS, FACEM, FACEP, Clinical Toxicologist, Director of Emergency Medicine; William J Louis, MB BS, FRACP, MD, Professor of Pharmacology; Chris J O’Callaghan, MB BS, FRACP, MD, Senior Lecturer; Albert G Frauman, MB BS, MD, FRACP, FACP, FRSM, Associate Professor of Medicine; M Laurence Mashford, MB BS, MSc, FRACP, Associate Professor of Medicine.

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et al.

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The Austin & Repatriation Medical Centre (A&RMC)Toxicology Service was commenced on 15 December1997 and is based on the Hunter Area Toxicology Service(HATS) model in Newcastle.

2

It is a joint service run bythe Department of Clinical Pharmacology & Therapeuticsand the Department of Emergency Medicine in collabora-tion with the Department of General Medicine. It managesall patients with intentional or accidental poisoning and/or chemical exposure. There is an on-call toxicologyconsultant available 24 hours. Patients requiring admis-sion are admitted under a combined Toxicology/GeneralMedicine unit. Admission to the service is offered to allpatients who have an expected length of stay of 12 h ormore. All admitted patients with deliberate self-poisoning(DSP) are reviewed by the liaison psychiatry unit priorto discharge. This multidisciplinary approach, as in theHATS model, is an important aspect of the managementof all deliberate self-poisonings, no matter how trivial.

2

This study was designed to consider two issues. Wefelt it important to compare our experiences to that of theHATS model to validate the conclusions of this landmarkAustralian study. In addition, our aim was to evaluate theimpact of the Toxicology Service on the A&RMC, in termsof inpatient and particularly ED care. The HATS studywas conducted at the regional toxicology treatmentcentre in the Hunter Area of New South Wales with areferral population of 485 000. The results were publishedin the

Medical Journal of Australia

in 1997. The study wasthe first of its kind to evaluate the impact of a centralizedcoordinated area based model for the management ofself-poisoning. This model, as reported, resulted in asubstantial reduction in bed stay (defined as minimallength of stay of 1 day by the New South Wales HealthDepartment).

Method

We conducted a descriptive, comparative study withretrospective data collection from the ED computer data-base (Victorian Emergency Minimum Database) over2 years from 15 December 1996 to 14 December 1998.The first year (15 December 1996 to 14 December 1997)was prior to the establishment of the Toxicology Serviceand the second year (15 December 1997 to 14 December1998) after the service began. The A & RMC is a tertiaryhospital that serves a population of about 622 600. Thesubjects were all patients who presented to the hospitalwhose primary complaint was that of poisoning orsuspected poisoning, including drug and alcohol with-drawal. We included both deliberate and accidental self-

poisonings in our data collection. Data on length of stay inthe ED, disposition, length of stay of admitted patientsand substance(s) involved were collected, collated and ana-lysed using

χ

2

testing.

Results

There were a total of 1316 poisoned patients presentingto the A&RMC ED over the 2-year study period (612in 1996/1997

vs

704 in 1997/1998). They represent 1.7%and 2.0%, respectively, of the total ED attendances forthe 2 years (35 144 in 1996/1997

vs

35 246 in 1997/1998).There were no significant events that occurred over the2-year period that impacted on ED attendances otherthan bed access, which was significantly different, with7.6% of admissions blocked in ED in 1996/1997 and 4.7%of admissions blocked in 1997/1998. The Department ofHuman Services Victoria defines that bed-access blockoccurs when a person does not leave the ED for aninpatient bed within 12 h of presentation. The generaladmission rate for both years was not statistically differ-ent (28.90% in 1996/1997

vs

30.53% in 1997/1998). Thegeneral ED population over the study period defined byNational Triage Scale (NTS) categories 1, 2 and 3 was notstatistically different (

P

= 0.1).We divided patients into five categories: (i) < 4 h in ED;

(ii) 4–12 h in ED; (iii) > 12 h in ED; (iv) admissions; and(v) transfers (Table 1). The overall number of presentationsincreased significantly from 612 in 96/7–704 in 1997/1998(15%,

P

-value = 0.002). However, there is no statistic-ally significant difference for the < 4 h, 4–12 h and > 12 hcategories in the ED. The main source of statistically sig-nificant difference is the 69.9% increase in the admissionscategory (

P

< 0.05). Although the number of transfersdecreased 21.4%, this is not statistically significant.

Table 1. Emergency department presentations according to disposition 1996/1997 versus 1997/1998

Disposition 1996/7n (%)

1997/8n (%)

Total

< 4 h ED stay 182 (29.7) 182 (25.9) 364

4–12 h ED stay 235 (38.4) 260 (36.9) 495

> 12 h ED stay 26 (4.2) 26 (3.7) 52Admissions 113 (18.5) 192 (27.3) 305Transfers 56 (9.2) 44 (6.3) 100Total 612 (100) 704 (100) 1316

ED, emergency department.

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Impact of toxicology service

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We further examined admission data by dividingadmission area into: admissions into ward, intensive careunit ( ICU)/coronary care unit (CCU) and psychiatric; andthe transfers into psychiatric and interhospital (Fig. 1).The CCU category included patients requiring cardiacmonitoring. Most of the admissions were to general wards;however, there were proportionately more ICU/CCUadmissions in 1997/1998. During the study period, theproportion of ICU/CCU admissions increased from 23.9%to 29.7%, compared with a decrease in the proportionof general ward admissions from 62.8% to 60.4% anda decrease in the proportion of psychiatric admissionsfrom 13.3% to 9.9%. The proportion of transfers to psy-chiatric hospitals increased from 53.6% to 59.1% whilethe proportion of transfers to other hospitals decreasedfrom 46.4% to 40.9%. However, none of these changes wasstatistically significant.

We then compared the (average length of stay) ALOSamong patients admitted to the A&RMC in the 2 years.We divided these into non-complicated and complicated(according to diagnosis related group, DRG, codings 889and 888) and referenced them to the statewide benchmarkfor ALOS. Admissions in 1996/1997 were under a generalmedical unit, and in 1997/1998 admissions were undera toxicology/general medical unit (Fig. 2). Overall, wedemonstrated a decrease in ALOS in 1997/1998 comparedwith 1996/1997. This was more evident in the complic-ated admissions group where the ALOS was better thanthe statewide benchmark.

Finally, we classified the drug classes and substancesinvolved in the self-poisonings. We counted the numberof cases and divided them into ED stays or admissions(Fig. 3). Multiple drug overdoses were implicated in74 ED presentations (13.8%) and 24 admissions (17.8%)in 1996/1997 versus 79 ED presentations (14.2%) and

57 admissions (21.9%) in 1997/1998. The most prevalentdrug classes involved in ED presentations for both yearswere alcohol, benzodiazepines, paracetamol and anti-depressants. This follows the trend of other recent studiesin Australia.

3,4

There was slight variation in the admissionsaccording to drug classes, but benzodiazepines weremost prevalent in both years, with antidepressantsand paracetamol also highly represented. Admissionsfor benzodiazepines, antidepressants and neurolepticsincreased substantially (103.7%, 260% and 175%, respect-ively) despite a constant number of presentations for thesedrugs. Admissions for paracetamol increased 55.6%despite a 37.3% fall in presentations. The proportion ofadmissions for alcohol intoxication increased threefold,reflecting both an increase in the number of patients andthe service’s decision to manage this condition.

Figure 1. a, b: Admissions; and c, d: transfers according to disposition, 1996–1997 versus 1997–1998. ICU, intensive care unit.

Figure 2. Average length of stay of admitted patients in ¤,1996–1997 versus ™,1997–1998; ¤, benchmark. DRG, Diagnosis related group.

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Discussion

Our data show a statistically significant increase indeliberate and accidental self-poisonings (from 612 in1996/1997 to 704 in 1997/1998) and in the number ofadmissions (from 113 in 1996/1997 to 192 in 1997/1998)while the general admission rate from the ED remainedunchanged. There was a significant reduction in ALOSfor patients admitted to the Toxicology Service, espe-cially in the complicated group. Although our other dataare not statistically significant, we noted an increase inthe proportion of admissions to ICU/CCU from 23.9% to29.7%. A recent study in Queensland estimated that22% of acute overdoses from ED were admitted to ICU.

5

However, this was without the existence of a ToxicologyService. There was minimal change in ED length of stay(EDLOS) (< 4 h, 4–12 h and > 12 h), despite significant

changes in exit block in the ED between the 2 years. Thisfinding is interesting. If one looks at the admission destina-tion of patients under the Toxicology Service there is areduction of general ward admissions and an increase inICU admissions with an associated decrease in interhospitaltransfers. The average time to transfer a patient from theED to ICU in A&RMC for all patients is over 5 h (5.29 hwith an SD of 3.24 h). With the introduction of the servicethere was a concerted effort not to transfer toxicologypatients, leading to a decrease in the transfer rate. Thecombination of these factors would be expected to lead toan increase in the EDLOS. One may suggest that thedecrease in ALOS compensated for this effect. Furtheranalysis of this observation is beyond the scope of thisnarrative study.

The commonest substances seen in self-poisoningsfor both years were alcohol, benzodiazepines, paracetamol

Figure 3. Emergency department presentations and admissions by drug class in: a, 1996–1997; versus b, 1997–1998. *Gases: carbon monoxide, vinyl chloride, chroming, freon, petrol fumes. †Chemicals: caustic agents/bleach, household cleaners, camphor, ammonia, turpentine, eucalyptus oil, copper carbonate.

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Impact of toxicology service

41

and antidepressants. The toxicology service tended toadmit more benzodiazepine, antidepressant, neuroleptic,paracetamol and alcohol overdoses. The increase inalcohol poisoning admissions is not surprising giventhe change in unit policy. However, the percentage ofadmissions involving multiple drugs also increased from17.8% to 21.9%.

From the ED perspective a toxicology service haspotential advantages and disadvantages. The advant-ages include having a multidisciplinary approach tomanaging all poisoned patients in whom deliberateself-poisoning is often symptomatic of an underlyingpsychiatric or social disorder.

6

The involvement of awell-trained psychiatric service, available on a 24-h basis,underpins the improvements identified by this review. Atour medical centre the presence of the Toxicology Servicehas consolidated the ED role in the first line managementof poisoned patients whose first and often subsequentpresentations are to an ED. The Toxicology Service is ajoint venture between the Department of EmergencyMedicine and the Department of Clinical Pharmacologyand Therapeutics. The role of the emergency physician inthe management of poisoning has been established asan area of expertise within A&RMC through clinicalpractice and teaching. The appointment of a medicaltoxicologist–emergency physician to our institution wasthe first in Australia.

The reduction in ALOS for admitted patients allowedfor greater bed access for all patients and potentiallyimproved ED exit block. We surmise that by decreasingALOS for the patients under the care of the ToxicologyService, the net increase in the general pool of unoccupiedbeds improves bed access for all ED patients. During thestudy period there was a reduction in hospital beds.

The HATS group found that many patients present-ing with DSP did so after a very brief interval andaccounted for a disproportionate number of hospitaliza-tions.

7

It is hoped that such a service can maintain a lowALOS for these patients and minimize their burden onhospital beds. On a more long-term basis it is hoped thatongoing training and research in toxicology will pro-vide community education and prevention strategies forrepeat DSP and improve the overall management of thesepatients.

Our initial analysis shows that treating more patientsfollowing the introduction of the Toxicology Service doesnot adversely affect LOS in the ED. In contrast to theNewcastle study, our study has defined an admission asLOS of > 12 h in the ED. Despite this the ALOS for admittedpatients has significantly reduced over the 2-year period,especially for complicated patients. The Newcastle study

incorporated all patients presenting to the ED in theircalculation for LOS. We feel that our reduction in ALOSfor admitted patients is even more significant because ofthis, given that many of their patients had short stays,confined within the ED and of lower complexity.

The disadvantages include the potential for over stretch-ing limited ED and hospital resources, and if the trendof attracting more patients continues there would be anincrease in demand on ICU/CCU beds.

We realize the limitations in our retrospective descript-ive study. These include data collection being subject tothe limitations of using a computer database. However,while this is a limited snapshot of trends over 2 years, thedemographics were similar and we can confidently statethat the increase in admissions was due to the increase inpresentations, independent of the Toxicology Service.There were no changes in overall ED attendances (35 144

vs

35 246) and the admission rate was not statisticallydifferent (28.90% in 1996/1997

vs

30.53% in 1997/1998).Further, the general ED population defined by NTS cat-egories 1, 2 and 3 was not statistically different (

P

= 0.1).

Conclusion

We conclude that there has been a significant increasein self-poisoning presentations and, admissions in the2-year study period. Although the establishment of theA&RMC Toxicology Service has had a neutral impact onthe EDLOS, it has achieved a decrease in the ALOS foradmitted patients, especially the complicated ones, whichwe feel has contributed to improved bed access for ED.This suggests that there is a beneficial role to be had inproviding a toxicology service without overburdeningthe ED and the hospital. There is evidence in the UnitedStates of America that a medical toxicology consultationservice can provide a resource-efficient means of treatingpatients with tricyclic antidepressant poisoning.

8

In addi-tion, we have seen a substantial increase in the num-bers of admissions for benzodiazepines, antidepressants,neuroleptics, paracetamol and alcohol in the second yearof our study. At the same time, more of these admis-sions have involved multiple drugs. If this potential forincreasing numbers and complexity of self-poisoningscontinues, we feel there is a valid role for a toxicologyconsultation service.

Acknowledgement

The authors would like thank Dr Mervyn J Silvapulle,

EMM175.fm Page 41 Wednesday, February 21, 2001 10:02 AM

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et al.

42

Department of Statistical Science, Latrobe University,

Bundoora, Victoria.

Accepted 29 September 2000

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