© 2008 The Royal College of Psychiatrists
A survey of in-patient and out-patient antipsychotic prescriptions in Hong Kong
*Castle Peak Hospital, Tuen Mun, Hong Kong, email: gabrielhung{at}hotmail.com
Castle Peak Hospital, Tuen Mun, Hong Kong
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AIMS AND METHOD
Antipsychotic prescriptions were analysed for a large sample of psychiatric in-patients and out-patients in Hong Kong. Case notes for patients receiving high doses were reviewed and compared with the most recent consensus statement issued by the Royal College of Psychiatrists.
RESULTS
Demographic and prescription data were obtained from 1254 in-patients and 19 986 out-patients. Antipsychotic medications were prescribed to 1129 in-patients and 7520 out-patients, with 9.2% of in-patients and 1.8% of out-patients receiving a high dose. Almost all case notes failed to record the clinical indications for high-dose prescribing or that the patient had been informed. Electrocardiograms were performed in a very small proportion of patients receiving a high dose.
CLINICAL IMPLICATIONS
Low levels of adherence to established guidelines for high-dose antipsychotic prescription were found in this study, with clinical and medico-legal implications. The results of this study highlight the need for staff education and regular audit of antipsychotic doses in the in-patient and out-patient setting.
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High-dose antipsychotic prescribing is a common practice worldwide (Diaz & de Leon, 2002; Harrington et al, 2002; Bitter et al, 2003; Chong et al, 2004). In a recent study of 3132 in-patients in 47 UK adult mental health services, 20% were prescribed a total dose of antipsychotic medication above the British National Formulary (BNF) recommendations (Harrington et al, 2002).
Recent reviews have failed to show any clinical benefit in prescribing high doses of antipsychotic medications (Freudenreich & Goff, 2002; Davis & Chen, 2004). However, there is clear evidence to show the harmful effects of high-dose antipsychotic therapy. There is evidence to link mortality with antipsychotic dosage and polypharmacy (Waddington et al, 1998; Joukamaa et al, 2006).
The Royal College of Psychiatrists (2006) currently recommends the use of high doses only after evidence-based strategies have failed, and as a carefully monitored limited therapeutic trial.
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Study population
All in-patients and out-patients receiving psychiatric services in the New Territories West Cluster (NTWC) in Hong Kong who received antipsychotic medications on 15 November 2006 were included in this study. The NTWC covers a catchment area of 223.17 km2 with a population of 1.1 million inhabitants. Out-patients followed up prior to 15 November 2006 were included if antipsychotic medications were to be self-administered on that day.
A full range of psychiatric services are provided, including general adult, community, liaison, old age, child and adolescent, learning disability, forensic, early psychosis, substance misuse and perinatal psychiatry. This psychiatric service is an accredited training centre of the Royal College of Psychiatrists.
High-dose prescriptions
A high dose was defined as a total daily dose of a single antipsychotic
exceeding the upper limit in the BNF. Where two or more
antipsychotics are used, the prescribed dose is converted to a percentage of
the maximum dose for each drug. If the sum of the percentages exceeds 100% the
patient is receiving a high dose (Yorston
& Pinney, 2000; Royal
College of Psychiatrists, 2006). For trifluoperazine, a maximum
daily dose was set at 50 mg. The maximum dosage for thiothixene and
ziprasidone, which are not available in the UK, were obtained from the US
prescribing information published by the manufacturer.
Adherence to established guidelines
Where a high dose is prescribed, the Royal College of Psychiatrists
(2006) recommends that:
- the clinical indications should be stated;
- the decision should be made by a fully trained psychiatrist;
- the patient should be consulted;
- electrocardiogram (ECG) should be performed at baseline, a few days after
prescription, and every 1-3 months in the early stages of treatment; and
- the outcome should be reviewed after a 3-month trial, and the dose should
be reduced back to conventional levels unless the clinical benefits outweigh
the risks.
The case notes of all patients receiving a high dose were obtained to identify the extent to which these recommendations are followed in clinical practice.
Data collection
In-patient data were collected using a pro forma to collect information on
all antipsychotic medications prescribed between 00.00 and 23.59 on 15
November 2006. Depot medications that were given prior to this date were
included if this date fell within the period between successive injections.
The prescribed dosage of ‘as required’ medications was obtained,
in addition to the dosage dispensed by nursing staff. Out-patient prescription
data were collected using the Clinical Management System database of the
hospital authority, which processes and stores information on all out-patient
prescriptions. A checklist was used to collect information from case notes to
obtain further data and this is listed in
Table 1.
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View this table: [in a new window] | Table 1. Adherence to guideline recommendations for cases receiving high-dose antipsychotic medications |
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Demographic and prescription data
Demographic and prescription data were obtained from 1254 in-patients and 19 986 out-patients. Antipsychotic medications were prescribed to 1129 in-patients and 7520 out-patients. Of those receiving antipsychotic medications, high doses were prescribed to 9.2% of in-patients and 1.8% of out-patients. The findings are summarised in Tables 2 and 3.
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View this table: [in a new window] | Table 2. Demographic and prescription data: all patients prescribed antipsychotics |
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View this table: [in a new window] | Table 3. Demographic and prescription data: patients receiving high-dose antipsychotic medications |
Case notes
Where available, case notes were reviewed to determine the date of the
high-dose prescription and whether the recommendations in the Royal College of
Psychiatrists (2006) were
followed. The results are summarised in
Table 1.
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Antipsychotic dosages
One antipsychotic was prescribed in 78.8% of in-patients and 83.1% of out-patients. This is in line with recommendations against the routine use of antipsychotic polypharmacy (Royal College of Psychiatrists, 2006). High doses were prescribed for 9.2% of all in-patients and 1.8% of all out-patients. A similar study conducted in the UK revealed 20% of in-patients receiving a high dose (Harrington et al, 2002). Antipsychotic polypharmacy was also more common in patients prescribed a high dose. High doses had been prescribed for an average of 571 days for in-patients and 1098 days for out-patients.
Documentation, precautions and review
The case notes showed a general lack of documentation in patients receiving
a high dose. Documentation of the indications for high-dose prescription was
found in only six cases. Only three case notes recorded that the patient was
informed, and very few patients received an ECG at baseline, 1 month, and 3
months after a high dose was prescribed. Due to a low index of suspicion or
unawareness, the psychiatrist may have failed to realise that a patient was
receiving a high dose. In addition, poor record-keeping and a lack of
knowledge of the current recommendations regarding documentation, monitoring
and review may have contributed to these findings. Further studies are
required to identify and target factors leading to low adherence to guideline
recommendations.
Limitations
This study was based on a large, representative population in Hong Kong,
including both in-patients and out-patients. Although there were no private
psychiatric hospitals or clinics in the catchment area, patients residing in
the area may be receiving private psychiatric services elsewhere. These cases
could not be identified for the purposes of this study. The cross-sectional
design of this study does not provide any information on longitudinal patterns
of prescription. This study did not investigate the reasons for high-dose
antipsychotic prescription. The degree of awareness of the Royal College of
Psychiatrists’ consensus statement
(Royal College of Psychiatrists,
2006) was not assessed.
Medico-legal implications
A prescription exceeding the maximum recommended dose results in an
unlicensed use of the medicine. A doctor who prescribes high-dose
antipsychotic medications is likely to be held liable for damage caused to a
patient, unless it can be shown that the damage was unrelated to the dosage
prescribed. The existence of clear guidelines advising against the use of
high-dose antipsychotic medications, together with poor documentation, a lack
of patient consent and a lack of ECG monitoring will render many claims
indefensible. The results of this study highlight the need for staff education
and regular audit of antipsychotic doses in both the in-patient and
out-patient setting.
G.B.K.H. would like to thank Dr S. P. Leung, Consultant, Castle Park Hospital, for supervising and supporting this research. This paper is based on data collected for the Part III Examination of the Hong Kong College of Psychiatrists.
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[Abstract/Free Full Text]
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