National Addiction Centre, Institute of Psychiatry/Maudsley Hospital, London SE5 8AF
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Correspondence: Dr John Marsden, National Addiction Centre, Institute of Psychiatry/Maudsley Hospital, 4 Windsor Walk, London SE5 8AF. Tel: 020 7919 3830; e-mail:J.Marsden{at}iop.kcl.ac.uk
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ABSTRACT |
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Aims To describe the prevalence of recent psychiatric treatment and current psychiatric symptoms and explore links between substance misuse, personal/social functioning and symptom severity.
Method Subjects were 1075 adults recruited to the National Treatment Outcome Research Study (NTORS), of whom 90% were opiate-dependent. Psychiatric symptoms at intake were recorded using sub-scales from the Brief Symptom Inventory.
Results Recent psychiatric treatment was reported by one in five subjects. Psychiatric symptom levels were high and females had elevated scores on all scales. Symptoms were elevated among opiate users who were also frequent users of benzodiazepines, alcohol and, in particular, stimulants. Gender, physical health, drug dependence and personal relationship problems were more powerful predictors of psychiatric symptoms than substance use.
Conclusions Addictions service providers should be vigilant to psychiatric problems among their clients at intake to treatment. Psychiatric symptoms are more closely linked to polydrug use than to opiate use in this population.
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INTRODUCTION |
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METHOD |
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Measures
Baseline intake data were gathered using a multi-dimensional client
assessment interview administered by participating clinical personnel at each
agency. The interview took 45-60 minutes to administer and contained several
standardised instruments in addition to measures developed specifically for
the study. A medical treatment history for the past 24 months was discussed
and recorded. This included the number and duration of addiction treatments
and general medical and psychiatric treatment episodes. Interviewers probed
the responses of the clients to clarify the nature of the primary presenting
disorder for each treatment episode.
Drug and alcohol use, physical health, psychiatric symptoms and personal/social functioning were assessed for the 90 days before intake. The intake assessment focused on self-reported frequency of taking heroin, methadone (prescribed and illicit), illicit benzodiazepines, cocaine base (crack), cocaine hydrochloride and amphetamines, using the Maudsley Addiction Profile (MAP; Marsden et al, 1998). The five-item Severity of Dependence Scale (SDS; Gossop et al, 1995) was used to assess the severity of self-reported dependence on the main problem substance. Physical health symptoms were recorded using a 49-item check-list from the Opiate Treatment Index (Darke et al, 1991). The severity of relationship, housing and legal problems was recorded using five-point self-rating scales (0-4) adapted from the Addiction Severity Index (McLellen et al, 1992). In the context of a research-oriented multi-dimensional client intake assessment, it was not feasible to undertake a formal psychiatric screening evaluation to determine lifetime and current diagnoses. Psychiatric symptoms were assessed using four sub-scales from the Brief Symptom Inventory (BSI); labelled anxiety, depression, paranoid ideation and psychoticism (Derogatis, 1993). We note that these symptom severity measures do not imply or diagnose functional nervous and psychotic psychiatric disorders. Substance dependence diagnoses were assigned by the authors based on data gathered from clients' intake interviews.
Statistical methods
In order to examine the nature of observed links between substance use and
psychiatric symptoms, cluster analysis was performed and cluster profiles were
described using 2 and one-way analysis of variance. Predictors
of psychiatric symptom severity were sought using multiple linear regression
with backward elimination of covariates. Multivariate analysis of variance was
used to assess links between the four psychiatric symptom sub-scales and
polydrug use patterns.
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RESULTS |
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Previous psychiatric treatment
In the two years before intake to treatment, 215 clients (20%) had received
treatment for a psychiatric disorder other than drug or alcohol dependence.
Ten per cent (n=112) had received in-patient psychiatric hospital
treatment in this period, and 14% of the clients (n=151) had received
out-patient hospital treatment for a mental health problem from a community
mental health team or general practitioner. A small group of clients reported
separate treatment episodes in both in-patient and community settings
(n=48; 4.5%). Forty-two per cent of these subjects were female.
Clients who had received treatment from a community mental health or general
practitioner reported attending an average of 18.4 (s.d.=30.3) appointments
during their treatment contact. Clients who had received in-patient
psychiatric treatment reported an average of 1.7 admissions and a total
average duration of treatment of 28.4 days (s.d.=37.4) in the past 24
months.
Psychiatric symptoms
The internal reliability of each of the four sub-scales from the BSI among
the NTORS cohort was satisfactory (anxiety, =0.87; depression,
=0.85; paranoia,
=0.70; psychoticism,
=0.73). Score means
of each sub-scale used were higher than published BSI norms for adult
psychiatric patients (Derogatis,
1993), being some 1.5 times higher for depressive and
paranoid-type symptoms and 1.3 times higher for the anxiety and psychoticism
measures. High levels of severity were reported on the suicidal ideation item
within the depression sub-scale. Twenty-nine per cent of the cohort reported
having suicidal thoughts during the three months before intake to treatment
(n=307); some 16.7% of men and 25.4% of women experienced the two
highest severity categories on this measure
(
2[1]=10.26; P=0.001). Overall, female
subjects reported higher symptoms across all psychiatric symptom scales. With
a cut-off taken at one standard deviation above the cohort mean, women had
elevated levels of symptoms across all subscales. The reporting rates, odds
ratios (ORs) and 95% confidence intervals (CIs) for women and men are as
follows: anxiety (32.3% v. 17.5%, OR=2.25, 95% CI=1.65-3.07);
depression (29.7% v. 14.9%, OR=2.41, 95% CI=1.74-3.35); paranoia
(26.9% v. 17.1%, OR=1.78, 95% CI=1.28-2.47); and psychoticism (33.3%
v. 19.6%, OR=2.05, 95% CI=1.51-2.79).
Scores on the four BSI sub-scales were significantly inter-correlated
(average r=0.70; range=0.62-0.78). For economy we first elected to
analyse subject response as a composite symptom severity index (SSI) by
summing the score weights (0-4) across the 23 items
(Derogatis, 1993). The SSI was
internally reliable (=0.93) and the mean score was 6.9 (s.d.=3.5;
range=0-15.7). The SSI was negatively skewed; just three subjects scored zero
on the scale. Correlations between the frequency of substance use and the SSI
were statistically significant but weak (opiates: r=-0.07,
P=0.021; prescribed methadone: r=-0.08, P=0.005;
stimulants: r=0.14, P<0.001; benzodiazepines:
r=0.14, P<0.001; alcohol: r=0.10,
P<0.001).
Substance use clusters
We hypothesised that there would be an indirect association between
substance use and psychiatric symptoms, given the prevalence of polydrug use
in the cohort and weak correlations between the SSI and individual substance
use. To assess this, substance use profiles for the cohort were created via a
cluster analysis of frequency of opiate use, prescribed methadone, stimulants
(cocaine and amphetamines), benzo-diazepines and alcohol. Standardised scores
on these measures were analysed sequentially using a -means
optimisation procedure. A four-cluster solution was chosen as optimal on the
basis of clarity of interpretation, proximity between cluster centres and
cluster size. Cluster size and cluster centres are shown in
Table 1.
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Subjects in each cluster were users of opiates to varying degrees (ranging
from 45% to 97% of the days used in the past three months before intake).
Cluster A represents the largest group within the cohort (n=425) and
contains subjects whose substance use profile was primarily oriented towards
frequent opiate use. The other three clusters contain subjects who were opiate
users but were also frequent users of the other assessed substances. Cluster B
(n=265) contains subjects who were using opiates less frequently than
the first cluster, but were taking prescribed methadone on a frequent basis
prior to entry to treatment. Cluster C (n=123) consists of subjects
who were oriented towards stimulant use and whose frequency of using cocaine
or amphetamines was, on average, some 2.4 standard deviations above the cohort
mean. Lastly, cluster D (n=262) describes subjects who, in addition
to heroin and frequent prescribed methadone use, were frequent users of
alcohol and benzodiazepines, with their average frequency of use for these
latter substances falling 1.0 and 0.9 standard deviations, respectively, above
the cohort mean. These four subject clusters were not uniformly distributed
across the two index treatment settings
(2[3]=112.32; P<0.001). Those in the
primary opiate-dependent group were more likely to receive treatment in a
community methadone programme (79.1%) and those in the opiate/methadone group
were marginally more likely to enter treatment in this setting (56.2%). Those
in the stimulant-oriented group were more likely to enter a residential
programme (69.1%) and those in the benzodiazepine/alcohol polydrug use group
were marginally more likely to enter a community methadone programme (55.0%).
The remaining analyses employed measures from the psychiatric symptoms and
personal/social functioning intake assessment domains to investigate the
characteristics of each subject cluster for substance use response (see
Table 2).
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The benzodiazepine/alcohol-oriented cluster contained subjects who were older than those in the other three groups. The opiate/stimulant cluster group and the opiate/benzodiazepine/alcohol-oriented groups were also more likely than the primary opiate/oriented groups to have had previous psychiatric treatment in the two years before admission (see Table 2). The 48 subjects who had received an episode of psychiatric treatment in both a hospital and a community setting had significantly higher SSI scores than the rest of the cohort (means=9.7 and 6.9, respectively; F[1,1071]=33.20; P<0.001). Both the stimulant-oriented and benzodiazepine/alcohol-oriented subjects reported more severe psychiatric symptoms than the other two groups. The methadone- and stimulant-oriented groups tended to report higher levels of physical health symptoms. There were no statistically significant differences in relationship, housing or legal problems.
Predictors of psychiatric symptoms
A multiple regression analysis was conducted between the SSI and the
following covariates: subject gender; the four cluster groups; SDS; physical
health symptoms; and relationship, housing and legal problems.
Table 3 shows the univariate
correlations between the substance use covariates and psychiatric health
symptoms and standardised regression coefficients (ß). Some 37% of the
variance in SSI was predicted (r=0.61). The most important predictors
of psychiatric symptoms were: the severity of physical health symptoms
(ß=0.44; P<0.001); the severity of dependence for the main
problem substance (ß=0.15; P<0.001); subject gender
(ß=0.12; P<0.001); and previous psychiatric treatment
(ß=0.12; P<0.001). These predictors all exerted stronger
associations with psychiatric symptoms than the substance use clusters.
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Finally, we assessed the pattern of scores on each of the sub-scales from the SSI (anxiety, depression, paranoia and psychoticism) across the substance use clusters via multivariate analysis of variance. With the use of Wilk's criterion, the combined dependent variables (symptom scores) were significantly different across the cluster groups (F=6.04, P<0.001). Univariate F tests indicated that subjects in stimulant-oriented and benzodiazepine/alcohol-oriented clusters (clusters C and D) had highest scores for anxiety (F=13.44, P<0.001). Subjects in the stimulant-oriented cluster reported the highest overall distress levels on the anxiety measure. For depressive symptoms, subjects in the opiate/methadone group (cluster B) had lower levels of depressive symptoms than other subjects (F=13.44, P<0.001). On both the paranoid and psychotic symptoms, subjects in the stimulant and benzodiazepine/alcohol groups had higher scores than the opiate-oriented groups. Here, again, subjects in the stimulant-oriented group had the highest overall symptom levels on the paranoia and psychoticism measures (F=7.04 and F=11.03, respectively; P<0.001).
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DISCUSSION |
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Relationship between substance use and psychiatric symptoms
A conditional rather than direct relationship between psychiatric symptoms
and substance use is suggested by the study. For primary opiate-dependent
clients with relatively low levels of polydrug use, pre-intake drug use does
not correlate directly with psychiatric symptoms. Opiate use and psychiatric
symptoms covary but only when opiate-dependent individuals report concurrent
frequent stimulant or frequent benzodiazepine and alcohol use. These results
are consistent with previous clinical reports of the psychiatric distress
experienced by many opiate- and stimulant-dependent individuals
(Swift et al, 1990;
Darke et al, 1994).
Our results stress the importance of assessing polydrug use patterns because
NTORS subjects who were either frequent stimulant or benzodiazepine/alcohol
users were likely to have severe anxiety, depression, paranoia and
psychoticism symptoms compared with subjects who were oriented towards opiate
use. In fact, depressive symptoms were relatively less severe among the opiate
users in receipt of a methadone prescription before intake.
Other more powerful predictors
Substance use aside, subjects with more severe physical health symptoms,
those with more severe substance use dependence, those who had previous
psychiatric treatment and those who reported higher levels of conflict in
their personal relationships had more severe psychiatric symptoms. The close
association between physical health and psychiatric symptoms has been observed
in previous studies (Darke et al,
1994; Marsden et al,
1998). As Ward et al
(1998) note, for many clients
the decision to enter treatment may be influenced more by personal problems
and distress than by heavy substance use.
Implications for services
These data illustrate the heterogeneity of treatment-seeking individuals in
terms of their substance use profile. Recognition of the importance of
understanding the links between substance use behaviour and psychiatric
disorders and their implications for treatment services is now gaining
momentum (Hall & Farrell,
1997; Johnson,
1997). The present study indicates that treatment service
personnel should undertake a thorough assessment of cocaine, amphetamines,
benzodiazepines and alcohol use. Opiate users with concurrent polydrug use may
need special consideration and treatment planning
(Strain et al, 1991).
The importance of responding to psychiatric symptoms among female drug users
entering addiction treatment should not be overlooked. People with addiction
problems have an elevated risk of suicide (see
Harris & Barraclough,
1997) and clients reporting suicidal ideation represent a priority
group who may require an intensive initial treatment, particularly those with
a history of suicide attempts. There is also value in conducting as thorough a
psychiatric assessment as is practicable in the context of routine clinical
practice. Such an assessment should attempt to trace the histories of
substance use disorders and psychiatric disorders, and gauge their interaction
and dynamics (Scott et al,
1998). An important objective should be to determine whether the
symptoms exhibited by individuals reach clinically significant levels for
specific disorders. We also suggest that the NTORS data imply that
opportunities exist for improved coordination between addiction, general
medical and specialised mental health services. A structured care pathway
approach may well be valuable in helping to organise and coordinate the timing
of addiction, general medical and specialist psychiatric interventions in
order to respond to client need.
Course of psychological symptoms
A critical issue for the NTORS study in this area concerns the course of
psychiatric symptoms during and after treatment. Strain et al
(1991) found that almost all
depressive symptoms reported by clients entering methadone maintenance had
ameliorated within the first week of treatment. An important further question
to be addressed in subsequent reports concerns the extent, timing and course
of change in psychiatric symptoms.
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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 March 17, 1999. Revision received July 23, 1999. Accepted for publication July 23, 1999.