Haringey Healthcare Trust and University Department of Psychiatry, Royal Free and University College Medical Schools, Royal Free Hospital, London
Institute of Psychiatry, London
St Mary's/St Charles Hospital, London
Royal Infirmary, Bristol
University of Limburg, Maastricht, The Netherlands
Institute of Psychiatry, London
Correspondence: Dr Kwame McKenzie, Department of Psychiatry and Behavioural Sciences, Royal Free and University College Medical School, Royal Free Campus, Rowland Hill Street, London NW3 2PF
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ABSTRACT |
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Aims To compare the course, outcome and treatment of psychosis in AfricanCaribbeans and British Whites in a large multi-centre sample.
Method A secondary analysis of 708 patients with research diagnostic criteria-defined psychosis from a 2-year, randomised controlled trial of case management. Outcome measures (hospitalisation, illness course, self-harm, social disability and treatment received) were adjusted for socio-economic and clinical differences between groups at baseline using regression analysis.
Results AfricanCaribbeans were less likely to have a continuous illness and to receive treatment with antidepressant or psychotherapy.
Conclusions The outcome of psychosis is complex but differs between UK AfricanCaribbeans and British Whites. This may reflect risk factors that increase the rate of psychosis in UK AfricanCaribbeans. Treatment differences require further investigation.
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INTRODUCTION |
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METHOD |
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The rationale for the study, the baseline characteristics of the study group and the outcome of the case management trial have been reported elsewhere (Burns et al, 1999; UK700 Group, 1999). In brief, patients with research diagnostic criteria (RDC)-defined psychosis (Spizer et al, 1978) aged 18-65 years who had had at least two admissions to a psychiatric hospital (one in the past 2 years) were admitted to a randomised controlled trial of intensive case management. Patients with organic brain damage or a primary diagnosis of substance misuse were excluded. Patients were identified by systematic review of in-patient and out-patient registers. Patients were entered into the study between February 1994 and April 1996.
Demographic and socio-economic information were documented at baseline. The Operational Criteria Checklist for Psychotic Illness (McGuffin et al, 1991) was completed on all patients for the time up to the baseline assessment, in order to produce diagnoses using computerised algorithms. This was completed using information from the whole of the patient records and a semi-structured mental state examination performed for completion of the Comprehensive Psychopathological Rating Scale (Jacobson et al, 1978). The World Health Organization (WHO) Life Chart (World Health Organization, 1992) was used to assess clinical history over the 2 years before study entry. Other baseline measures included the Camberwell Assessment of Need (Phelan et al, 1995), the Lancashire Quality of Life Profile (Oliver, 1991) and the WHO Disability Assessment Schedule (DAS; World Health Organization, 1988).
Ethnicity
Ethnicity was assigned by observers according to the Office of Population
Censuses and Surveys (OPCS) ethnicity categories (OPCS, 1992). This was
supplemented by information on patients' and patients' parents' place of
birth. The aim was to produce a group of Caribbean origin and as homogeneous a
British White group as possible for comparisons.
The OPCS White category can include people from a variety of countries. The largest minority ethnic group, the Irish, are usually subsumed in this group although they may have different mental health needs to those born in the UK of British parents (Littlewood & Lipsedge, 1997). This can make explanations of any differences between groups difficult. In this study, White British=OPCS category White with mother and father born in the UK.
Patients of Caribbean origin are also a heterogeneous group. However, this group has shared histories, reasons for migration, concentrations in certain geographical areas of the UK and shared experiences of discrimination that may produce similarities in their needs and experience of services. We did not include those of African origin. Those of mixed parentage were included in the group of Caribbean origin if they had been assigned to the BlackCaribbean or Black Other OPCS group. This may reflect the experience that patients have had with the mental health system and society in general. Patients of mixed Caribbean and African parentage were excluded, as were patients with one parent from an unspecified country.
In this study Caribbean origin=OPCS BlackCaribbean or Black Other with mother or father born in the Caribbean or UK.
Follow-up
Stratified randomisation ensured that equal proportions of White British
and AfricanCaribbean patients were allocated to each treatment arm.
Patients were followed up for an average of 2 years from the time they were
randomised. They were re-interviewed at 1 and 2 years. At 1 year all the
instruments except the WHO Life Chart
(WHO, 1992) were repeated. At
2 years all the instruments used at baseline were repeated. We present data
for the 2-year follow-up.
Follow-up interviews were undertaken by independent researchers who were not involved in patient care. Patients and, when available, relatives and carers were interviewed. Each patient's case manager was interviewed. Case managers had a detailed knowledge of their patients. Throughout the study they carefully documented every visit to their patients for an assessment of care received and case management model fidelity. Other mental health professionals involved in the case were interviewed. Patients' case notes were also reviewed. The aim was to construct as accurate a picture as possible of the course of the illness, admissions and treatment.
Measurement of outcome
Outcome in psychosis is complex and variables that measure outcome are
often interrelated. Van Os et al
(1996) identified six
dimensions of course and outcome in psychosis:
We have represented these six dimensions of outcome with 11 measures used in the UK700 project (Table 1).
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Over the follow-up period, course type was rated using the WHO Life Chart (WHO, 1992) as episodic (no episode longer than 6 months), continuous (no remission longer than 6 months), neither episodic nor continuous, and not psychotic in this period. The usual severity of symptoms rating indicated the symptomatic level of the patient during the most of the follow-up period. Ratings were severe, moderate, mild or recovered. Self-harm included all attempts at self-harm, regardless of the outcome (i.e. both parasuicide and completed suicide were included).
Treatment variables
In addition to information on course and outcome, data on five areas of
treatment over the follow-up were also collected:
The measures used and methodology replicate those of McKenzie et al (1995). However, in addition to the measures used above, McKenzie et al (1995) reported involuntary admissions over the follow-up period, results from the Iager scale (Iager et al, 1985) to measure negative symptoms and results from the Hamilton Rating Scales for Depression (Hamilton, 1960). This information was not collected by the UK700 trial.
It should be noted that the measures of outcome in this study are not the same as the main outcome measures for the UK700 study. We decided before the analysis to use the same outcome variables as we had used previously so that we could compare the results of the present study with our previous study (McKenzie et al, 1995). We also decided, a priori, to use the same plan for statistical analysis.
Analysis
The means of continuous variables and the proportions for binary variables
were compared between the two ethnic groups. Means and proportions were
adjusted using regression analysis to yield odds ratios. Models included age,
diagnosis, educational level and time from onset of the illness to study entry
as possible explanatory variables.
Variables measuring time (e.g. time spent in hospital, time unemployed, etc.) were expressed as the proportion of the length of the follow-up period. Some outcome variables were transformed into dichotomous variables if they inclined towards two categories. For example, course of illness was transformed into continuous and non-continuous and usual symptom severity was transformed into recovered and non-recovered. Similarly, for continuous variables such as time in psychotherapy and time on anti-depressants, which were severely skewed, tending towards a half-normal distribution (presence-absence), dichotomisation was also considered more appropriate. Analyses were carried out using SPSS for Windows 8.0.
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RESULTS |
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Follow-up
Sources of information
Usable information was available for 199 AfricanCaribbeans and 231
British Whites. One patient had been discharged, two had moved, one had
refused contact and three could not be contacted.
There was no difference between the groups in the mean number of sources of information (patient, carers, relatives, mental health professionals, case notes, others) used to complete the interview schedule at baseline (AC, 2.6; BW, 2.6) or follow-up (AC, 2.6; BW, 2.7).
At follow-up, 26 AfricanCaribbean patients (13%) and 35 British Whites (15%) were not interviewed. There were no differences between the groups in the proportions of patients who refused interview or the reasons for non-interview. The most common reason for non-interview was refusal; 25 patients refused to be interviewed (6.5% AfricanCaribbeans and 5.5% British Whites). There was no difference between the groups in the mean number of sources of information that were used for those patients who were not interviewed at follow-up (AC, 2.0; BW, 1.8).
Length of follow-up
Patients were followed up on average for 24 months. Some patients were
followed up for less than 24 months because they were recruited later than
others and the study had to be completed. Some patients were followed up for
more than 24 months because of a delay in arranging the second interview. Over
50% of patients were interviewed within 1 month of their 2-year interview
date. There was no difference between the groups in the proportions of
patients interviewed early, late or on time.
Univariate analysis
There were no significant differences in symptomatic outcome or illness
course on univariate analysis but significant differences were found in the
treatment received over the follow-up period (see
Table 2).
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Multivariate analysis
Significant differences between the groups for the prescription of
antidepressants and psychotherapy but not day treatment/rehabilitation or
lithium therapy remained after we controlled for diagnosis, age, length of
illness before study entry and education. In addition, after controlling for
confounders, AfricanCaribbeans were nearly 40% less likely to have a
continuous illness course than British Whites
(Table 3).
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DISCUSSION |
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In this sample, recruitment of patients was not time-limited (as occurs when consent needs to be obtained at the point of hospital admission). We were able to enlist the help of people already involved in the clinical care of each patient to facilitate study entry and were able to include potentially uncooperative patients who would normally not take part in such studies.
Our sample could be criticised because it was not a first-onset study. Patients with established illness were recruited. However, even when patients are identified at first onset, there are differences between AfricanCaribbeans and British Whites in the length of illness before they have been seen, which have to be taken into account using multivariate analyses like those undertaken here (Harrison et al, 1999). There are also well-documented differences in the likelihood of general practitioners identifying mental illness in AfricanCaribbeans and Whites (Lloyd et al, 1998) and in the subsequent treatment or referral to secondary services (Sashidharan & Commander, 1998).
Our sample also could be criticised because it is not comprehensive. Patients would have been identified only if they were on in-patient or out-patient registers. If those identified as suffering from psychosis in either group were more likely to be lost to follow-up, this would lead to selection bias. However, longer-term studies have not shown a significant difference between groups in the likelihood of being lost to follow-up (Goater et al, 1999; Harrison et al, 1999).
Patients could be included in the sample only if they agreed to take part in a case management study. AfricanCaribbeans could have been more likely to refuse study entry and this could have led to selection bias. However, no difference in refusal rates between groups was found in an analysis of those who were eligible but did not take part (details available from the author upon request).
The criteria for study entry could have introduced bias. For instance, patients had to have had two admissions to be eligible. Bias may have been introduced if the course of illness was different between the two groups. If AfricanCaribbeans were more likely to have only a single episode of illness (brief reactive psychosis; Littlewood & Lipsedge, 1981), they may not have entered the study. A recent study has not shown differences in the proportions of patients who have only a single episode when AfricanCaribbeans are compared with a number of other groups (Goater et al, 1999). Moreover, any bias because of an exclusion of AfricanCaribbeans with brief reactive psychosis would have made it less likely that we would show a better outcome with regard to course of illness.
The criteria for entry could have introduced bias in a different way. Some studies have shown that people of Caribbean origin are more likely to be readmitted in the year after their first episode (Birchwood et al, 1992; McGovern et al, 1994; Bhugra et al, 1997). If this were so, they would have fulfilled the study entry criteria for admission earlier in their illness. This could be an explanation for their shorter time between onset and study entry. However, this association disappears when diagnosis is taken into account, so it could reflect actual differences between the groups. Furthermore, Recent studies have not shown differences in numbers of admissions or course of illness when longer time frames for follow-up have been used.
Our study could also be criticised because all the centres were in the inner city. However, the vast majority of patients of Caribbean origin live in inner-city areas (Nazroo, 1997).
Data collection: blinding
Our data collection could be criticised because assessors were not blind to
the ethnicity of patients. None of the assessors was part of the team who
envisioned this analysis and none was aware that data from two arms of the
study were to be pooled to investigate globally the outcome of psychosis in
AfricanCaribbeans and Whites. The primary hypothesis of the UK700 study
was that intensive case management would produce a better outcome than
standard case management (UK700 Group,
1999). The trial did not show any difference in outcome
(Burns et al, 1999)
and we believe that this underlines the accuracy of assessments made by
researchers. Of course, a criticism of all the studies that look at the course
of illness in these two groups is that they rely on case note documentation
and information from a number of people (case workers, carers and relatives)
who are not blind to the ethnicity of the patients.
Comparison with other studies
The outcome of psychosis in people of Caribbean origin in the UK is
complex. Administrative outcomes, such as readmission rates and compulsory
admissions, are reported as poor but there are mixed reports of rates of
recovery and the course of illness.
A recent population-based first-onset study concluded that findings of its own and other studies are consistent with a marginal effect (if any) for better outcome in AfricanCaribbeans (Harrison et al, 1999). The authors hypothesised that inconsistent findings could be expected because of the small sample sizes of studies. We would add that inconsistent findings may be due partly to differences in definitions of the AfricanCaribbean and comparison groups and differences in study design. There are problems with directly comparing this study with first-onset studies even though we have tried to minimise these.
We set out here to try to replicate the findings of our previous study in which people of Caribbean origin in the UK were found to be less likely to suffer from a continuous illness and were more likely to be recovered and also imprisoned over a follow-up period. They were less likely to be treated with antidepressants, lithium and rehabilitation and were less likely to self-harm (McKenzie et al, 1995). We have been able to define AfricanCaribbean and British White groups similarly in this and the previous study. We have partly replicated the findings.
Illness course and recovery
We have found that people of Caribbean origin are less likely to suffer
from a continuous illness. We have found this despite the fact that our sample
was more homogeneous than others and may have been expected to show less
variation between AfricanCaribbean and British White groups. The
outcome of psychotic illness is more severe in those with neurodevelopmental
or neurological abnormalities. In a separate cohort we have shown that people
of Caribbean origin with psychosis are less likely to have a premorbid
neurological illness than British Whites (details available from the author
upon request). People of Caribbean origin in the UK may be less likely to have
continuous illness because, as a group, the risk factors for their psychoses
are quantitatively different from those for British Whites.
People of Caribbean origin were not more likely to be recovered over the follow-up period in this study. This could be because there were no differences in the symptomatic course, as has been found by other recent studies (Goater et al, 1999; Harrison et al, 1999), but it could be because our sample of patients with established illness was too homogeneous for a difference to be shown. Another possible reason for an inability to show differences in outcome could be that they were masked by treatment differences.
Treatment differences
People of Caribbean origin in this study were less likely to receive
psychotherapy and were less likely to be treated with anti-depressants,
regardless of diagnosis. We found these findings hard to account for, given
that patients were being closely followed up and were enrolled in a case
management study. We did not find differences in imprisonment, hospital use or
the use of other treatments. Lack of treatment of depression could reflect
real differences in psychopathology but previous studies have shown that
depression is often missed in people of Caribbean origin
(Lloyd et al, 1998;
Sashidharan & Commander,
1998) and we did not find differences in suicide or self-harm
between groups in this study.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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REFERENCES |
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Received for publication October 25, 1999. Revision received May 9, 2000. Accepted for publication July 30, 2000.