The results of a multi-centre audit of the prescribing of antipsychotic drugs for in-patients in the UK

AIMS AND METHOD

Forty-seven UK mental health services participated in a 1-dayaudit of prescribing of antipsychotic drugs. Audit standardswere derived from national guidelines and consensus statements.

RESULTS

Of the 3132 patients, 20% were prescribed a total dose of antipsychotic medication above that recommended by the British National Formulary. The majority of case notes failed to record an indication forhigh-dose prescribing or that the patient had been informed;only 8% had undergone an electrocardiogram. Forty-eight percent of patients were prescribed more than one antipsychoticdrug.

CLINICAL IMPLICATIONS

Antipsychotic prescribing for in-patients often runs counterto existing guideline recommendations. It is likely that manypatients who are prescribed high doses or polypharmacy areunaware that their prescription is out of line with guidelinerecommendations and is inadequately monitored.

Introduction

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Introduction

In the UK, 23 antipsychotic drugs are available on prescription,many by more than one route. Most side-effects of these drugsare dose related, cause substantial morbidity and may contributeto poor treatment adherence (American Psychiatric Association, 1997).It remains unclear whether the risk of sudden death, acknowledged to occur with antipsychotic drugs, is dose related (Royal College of Psychiatrists, 1997). Existing research offerslimited guidance on optimal prescribing in individual circumstances.However, reviews have concluded that, in general, the use ofhigh doses or of polypharmacy (simultaneous use of more thanone antipsychotic drug) offers little, if any, benefit overmoderate doses of a single drug, in relation to the disadvantages (Royal College of Psychiatrists, 1993). This evidence has influencedthe development of national guidelines and consensus statements.

Method

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Method

Development of the audit standards
Five English-speaking countries have published national guidelinesor consensus statements that refer to the prescribing of antipsychoticdrugs (American Psychiatric Association, 1997; EPPIC Statewide Services, 1999;New Zealand Ministry of Health, 1996; RoyalCollege of Psychiatrists, 1993, 1997; Working Group for theCanadian Psychiatric Association and the Canadian Alliancefor Research on Schizophrenia, 1998). All advise against theuse of high doses other than in exceptional circumstances.Four make a similar, explicit recommendation in respect ofpolypharmacy. Audit standards were derived from these documentsand were presented to, and agreed by, a separate ‘expertpanel’ of psychiatric pharmacists and psychopharmacologists.The standards audited, and the measures used to audit them,are shown in Table 1.

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Table 1. Audited standards and the findings

Dose
The British National Formulary (BNF; British Medical Association & Royal Pharmaceutical Society of Great Britain, 1999)states a maximum recommended dose, or a dose range for allantipsychotic drugs except trifluoperazine. The Royal Collegeof Psychiatrists' consensus statement (Royal College of Psychiatrists, 1993)recommends that, when an antipsychotic is given at a dose above the BNF limit the decision should be made by a fully trained psychiatrist; the patient should be informed and his/her consentobtained; an electrocardiogram (ECG) should be performed; regularpulse, blood pressure and temperature checks should be made;and fluid intake should be monitored. A trial of a high-doseprescription should not last longer than 3 months. If therehas been no improvement, the dose should be reduced back towithin the standard range.

Polypharmacy
The BNF advises against polypharmacy. However, the College consensus statement suggests that there are some occasions whenit is appropriate to give more than one antipsychotic drugconcurrently for short periods. These include when changinggradually from one drug to another and when giving a more sedativeand/or injectable antipsychotic drug to someone who is veryagitated and who is already prescribed another antipsychoticdrug on a regular basis.

High dose caused by polypharmacy
The College consensus statement clearly states that high-doseprescribing may occur because of the additive effects of twoantipsychotic drugs that are prescribed concurrently. Thereare two methods of calculating whether the ‘total doseof antipsychotic drug’ exceeds the recommended level. One is to convert the doses of the drugs into ‘chlorpromazine equivalents’ and add these. The other approach, whichwas used in this audit, is to convert the prescribed dose toits percentage of the upper recommended dose (or maximum dose)for each drug and then to add the percentages (Yorston & Pinney, 2000).When the sum exceeds 100, the patient is consideredto be receiving a high dose.

For the purpose of the audit, the maximum daily dose for trifluoperazine was taken to be 50 mg.

Recruitment of sites
In February 1998, all UK adult mental health services were invitedto take part in the audit; 47 did so. Services from every partof the country and from every main socio-demographic group(inner city, urban, mixed and rural) participated. They includedone private hospital and one high security hospital. A totalof 241 psychiatric wards (154 acute admission, 69 rehabilitationand 18 forensic) were involved. All wards were primarily for the treatment of people aged 18-65.

The audit
Local staff used a pro forma to collect information about allin-patients who were prescribed antipsychotic medication on5 October 1998. This included details of all prescriptionsfor antipsychotic medication (drug, daily dose and route ofadministration). For each prescription, it was noted whetherthe drug was to be administered routinely or whether it wasto be given ‘as required’ at the discretion ofnursing staff. Frequency of administration was recorded forantipsychotic drugs prescribed as depot injections and, forzuclopenthixol acetate, the dose prescribed in the previous72 hours.

Data collectors used a checklist to collate information fromcase files for comparison of practice with the standards setout in Table 1.

Data collection and management
Staff from each site attended a workshop at which the auditstandards and methods for data collection were presented anddiscussed. Completed forms were returned to the Royal Collegeof Psychiatrists' Research Unit where the data were analysedusing SPSS for Windows, version 8.

Results

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Results

Returns gave information about prescribing practice relatingto 3132 in-patients.

Frequency of prescribing of high doses and polypharmacy
Antipsychotic medication at a total dose above the BNF recommended daily limit was prescribed to 613 patients (20%). For only asmall minority of cases (n=34; 5.5% of those prescribed a highdose) was this due to the prescription of a single type ofantipsychotic drug at a high dose. For the remainder, high-doseprescribing was due to a combination of two or more types ofanti-psychotic drug. If only antipsychotic drugs prescribedfor routine administration were considered, 318 patients (10%of the total sample) were prescribed a high dose.

In all, 1487 patients (48%) were prescribed more than one antipsychotic drug on the census day. The results of the audit are summarisedin Table 1.

Discussion

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Discussion

As there was no random selection of the participating services,the cohort may not be fully representative. However, unitsfrom all parts of the country took part and the sample is large,containing perhaps 15-20% of all people in a psychiatric hospitalon the census day. This estimate is extrapolated from the bednumbers for England (Department of Health, 1998).

Why are high-dose prescribing and polypharmacy so common?
The finding that patients in hospital are commonly prescribedhigh doses is consistent with six smaller scale audits or surveysof psychiatric in-patients carried out in the UK over the pastdecade (Chaplin & McGuigan, 1996; Krazucki & McFarlane, 1996;Milton et al, 1998; Newton et al, 1997; Warner et al,1995; Yorston & Pinney, 1997). These studies involved1084 patients prescribed antipsychotic medication, 32% (n=344)of whom were prescribed a high dose.

A number of factors need to be considered when interpretingthe findings from the multi-centre audit, they are as follows.

The sample is cross-sectional
This means that it will contain a higher proportion of patientswith longer lengths of stay, and probably higher levels ofdisturbance and disability, than a cohort of consecutive admissions.Also, the audit gives no indication of longitudinal patternsof prescribing. The potential impact of this is illustratedby the finding that 12% of patients on more than one antipsychotic were in the process of being switched from one antipsychoticto another.

Ward conditions
About two-thirds of the patients were on acute admission wards.The rate of admission to these wards has increased considerablyover the past 15 years despite a reduction in bed numbers.This has resulted in people who are severely disabled and highlydisturbed being concentrated on these wards. Some of the prescribingmight therefore reflect the use of antipsychotics to controlbehaviour, in the context of a disturbed ward environment, ratherthan the rational treatment of psychotic symptoms. Furthermore,the need to free up beds for new admissions creates pressureto discharge people quickly. This might encourage rapid escalationof doses or the premature addition of a second type of antipsychoticdrug. The commonest reason given for the use of polypharmacywas that a single drug had failed to control symptoms. It isnot known how often the trial of a single antipsychotic drughad lasted > 6 weeks, as recommended by a number of nationalguidelines.

Medication given at the discretion of nurses
The decision as to whether medication should be given at levelsexceeding those recommended by the BNF had, in effect, beenleft to nursing staff in about half of cases where a doctorhad prescribed a high dose. This was through the writing upof ‘as required’ medication. The audit neitherdetermined whether this was intentional (see below) nor whether nursing staff were sufficiently trained in psychopharmacologyto make such decisions. The writing of ‘as required’could also lead to the unintentional and unknowing administrationof a high dose (Milton et al, 1998).

Psychiatrists might not be aware that they are prescribing high doses
For two-thirds of patients to whom it applied, the case notescontained no explicit statement that BNF limits had been exceeded.This might reflect sub-optimal record keeping, a lack of awarenessor a combination of both. Nearly 95% of high-dose prescribingwas due to polypharmacy. It is possible this represents a secondcause of ‘covert’ high-dose prescribing whereinclinicians lose sight of total additive dose when they givemore than one type of drug at the same time (Tyson et al, 1999).

Prescribers might disagree with the guidelines
When an audit highlights significant divergence from recommendedpractice, the ‘validity’ of the guideline shouldbe reconsidered as well as the behaviour of clinicians. Theresearch base for the guidelines, which informed this audit,is not strong and there might also be questions about the extentto which the research findings can be extrapolated to the real-life clinical situations encountered in modern British psychiatry.Also, the recommendations for maximum doses take no accountof patient factors, such as age, gender, ethnicity, body mass,smoking or other medication that might influence response orside-effects. Furthermore, there are apparent inconsistenciesbetween BNF maximum recommended doses and comparisons betweendrugs based on commonly used tables of equivalence. This is particularly important, given the extent to which highdose prescribingis associated with polypharmacy.

Precautions and consent
Fewer than 10% of patients prescribed a high dose had undergonean ECG. There might be a number of explanations for this:

it might reflect the lack of awareness that a high dose hasbeen prescribed
psychiatrists might be unaware both of theimportance of sucha test and of the College guideline (Hendersonet al, 1997)
trainee psychiatrists might not feel proficientin interpretingthe results of an ECG (Warner et al, 1996).

A lack of awareness of the psychiatrist that a high dose hasbeen prescribed might also partly explain why as many as 80%of patients appear not to have been informed, let alone giventheir consent. Patients have made allegations of negligenceinvolving doses of antipsychotics outside the BNF recommendedrange (Bradley, 1997). The lack of objective data to supportthe efficacy of high doses, in conjunction with the lack ofinformed consent (Brabbins et al, 1996) and failure to conductsimple precautionary tests, are likely to make such allegationsdifficult to defend against.

Prescribing behaviour has probably changed since the 1998 auditowing to the increased use of atypical antipsychotic drugs.This supports the case for further audits of this type.

Acknowledgments

The authors thank the ‘expert panel’ of psychopharmacologists and psychiatric pharmacists who helped draft the standards usedin this audit: Professor T. Barnes, Dr J. Cookson, J. Donoghue,Professor M. Lader, Dr L. Pilowsky and D. Taylor. The datawere collected by staff from the 47 mental health servicesthat participated in the audit.

References

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