Screening for Mental Illness With the Addiction Severity Index

I Lisa Dixon, M.D., Patrick Myers, M.A., Jeanette Johnson, Ph.D., Eric Corty, Ph.D.

B e authors assessed the relationship of the psychological composite score (PCS) of the Addiction Severity Index (AS4 to the presence of current DSM-III-R depressive, anxiety, psychotic, and somatoform disorders. A total of365patients in two inner-city psychiatric units received the Structured Clinical Interview for DSM-III-R (SCID) and the ASI. The presence of a current DSM-III-R psychiatric diagnosis was significantly correlated with the PCS (P c 0.001). Con- troZIing for substance abuse, affective (P < 0.01) and anxi- ety (P < 0.02) disorders significantly contributed to the ASI PCS. Individual PCS items were associated with the dzfferent types of mental disorders. The MI PCS was significantly related to the presence of current DSM-III-R psychiatric di- agnoses, especially depressive and anxiety disorders. Clus- ters of ASI PCS items may have utility in screening for patients in the substance abuse treatment setting who need psychiatric services. (American Journal on Addictions 1996; 5 : 301-307)

he frequent comorbidity of mental ill- T ness and substance abuse disorders is well established. As many as 50% or more of individuals presenting in either mental illness and substance abuse treatment set- tings have both disorders.'-5 Individuals with concurrent substance abuse and men- tal illness disorders are more difficult to assess and treat and have poorer outcomes than those with single di~orders.~.~,' Of the many challenges presented by dually diag- nosed patients, perhaps the first is the need to detect accurately both mental illness and

substance abuse. Although there is an emerging literature on the detection of substance abuse in persons receiving treat- ment for severe mental illness,a10 less is known about how to identlfy mental illness in persons diagnosed with psychoactive substance use disorders.

Many factors limit our ability to iden- tlfy mental illness in individuals who also abuse substances. Many substance abusers have psychosocial deficits that may inter- fere with our understanding of their psy- chological functioning." For example, it

Received March 15, 1995; revised October 6, 1995; accepted November 6, 1995. From the Department of Psychiatry, University of Maryland. Address correspondence to Dr. Dixon, Department of Psychiatry, University of Maryland, 645 West Redwood St., Baltimore, MD 21201.

Copyright 0 1996 The American Academy of Addiction Psychiatry.

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~ has been well-documented that substance- abusing patients have poor educational levels (or illiteracy), high rates of unem- ployment, and a lack of marketable job

Even though a high level of depres- sion has been found in many substance abuser^,'^.'^ it has been suggested that depression may be a concomitant of the surrounding social conditions in substance- abusing patient^.'^ This underlines the di- agnostic dilemma of retrospective data: the data do not allow us to determine which problem came first, the substance abuse or the observed psychiatric problem.

Another obstacle to detecting mental illness in persons who abuse substances is the overlapping nature of the symptoms of mental illness and substance intoxication and withdrawal.16 To accommodate this, the DSM-N recommends waiting at least 4 weeks after the cessation of symptoms of acute withdrawal or intoxication before making the diagnosis of an independent non-substance-induced mental disorder. l7

Our own work shows that there is de- creased, though still adequate, reliability of mental illness diagnosis in the presence of a substance use disorder."

Studies focusing on the prevalence of mental illness among substance-abusing populations typically have used the Diag- nostic Interview Schedule (DIS), psychiat- ric evaluations, and the Structured Clinical Interview for DSM-111-R (SCID) to ascertain psychiatric diagnose^.'^ These assessment techniques are relatively time-consuming and expensive. Saxon and colleagues" used the General Behavior Inventory to identify persons with unipolar and bipo- lar affective disorder among substance- abusing patients. We are unaware of studies that aim to determine the potential utility of convenient, abbreviated assess- ment techniques to screen for mental ill- nesses in substance-abusing populations.

One potentially useful assessment tool is the Addiction Severity Index (ASI). Originally developed by McLellan and

it is a global assessment de- vice to measure both the need for and the effectiveness of treatment for persons with substance abuse disorders. The AS1 con- sists of seven problem domains, one of which measures psychological problems and need for psychological treatment. With well documented reliability and valid- ity,21,22 even among persons with substance abuse and major psychiatric disorder^,'^ it is used widely in substance abuse treat- ment settings. Easy to administer and rela- tively short, the AS1 may be useful in screening for mental disorders in persons who abuse substances. The present study examined the utility of the psychological domain of the AS1 to address the following questions: 1) Is the AS1 psychological com- posite score (PCS) correlated with the presence of a DSM-III-RZ4 mental disorder? 2) Do the presence of mood, psychotic, anxiety, and somatoform disorders signifi- cantly and differentially relate to the PCS? 3) Are the individual items of the AS1 PCS differentially correlated with the presence of these disorders?

METHODS

Subjects

Patients were drawn from a larger study described in detail e l ~ e w h e r e , * ~ ~ ~ of consecutive admissions to two urban psy- chiatric hospitals, one state-operated and one university-operated, from April 1988 to December 1990. Study subjects ranged in age from 18 to 65 years, resided in the hospital catchment area, spoke English, and were Iegally and medically compe- tent to give informed consent. There were a total of 365 subjects in the present study: 59% were men, 43% white; sub- jects had a mean age of 33.2 ? 9.6 years. Fifty-eight percent had never been mar- ried, and the mean educational level was 11.0 k 2.4 years.

All patients were screened within 1

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week of admission. Eligible patients were then approached for consent, and, if con- senting, received research evaluations as soon as their clinical condition permitted. The length of time between hospital admis- sion and research interviews was a mean of 16.0 k 20.6 days.

Measurements

Structured CZinica( Intenria0 for DSXf-III-R- Patient Version (SQLLP).* The SCID-P assesses current (past month) and lifetime DSM-111-R Axis I diagnoses. SCID-P diagno- ses were based on a face-to-face interview and review of the patient’s clinical record by an independent research clinician who did not discuss the diagnosis with the pa- tient. The interrater reliability (kappa) for the SCID principal diagnosis in this study was 0.81. Only current, and not lifetime, disorders were considered for this study because we were interested in comparing these diagnoses with the PCS, which is calcu- lated on symptom reports of the last 30 days.

Addiction Saterity Index (So. The AS1 is a structured interview designed to assess problem severity in seven areas commonly affected in alcohol and/or drug abusers: medical condition, employment, alcohol use, substance use, legal issues, family and social relations, and psychiatric status.” The AS1 measures subjective and objec- tive information on the number, extent, and duration of problem symptoms in the patient’s lifetime and in the past 30 days. In each area, a composite score is com- puted by using critical items from the scale. These composite scores range from 0 (no problem) to 1 (most severe prob- lem) and reflect the severity of the per- son’s difficulties and need for services in the identified life domain.

This study reports on data from the psychological domain. In this domain, sub- jects are asked whether they have during their lifetime and in the 30 days prior to

admission experienced the following: 1) depression; 2) serious anxiety or tension; 3) hallucinations; 4) trouble under- standing, concentrating, and/or remem- bering; 5 ) trouble controlling violent behavior; 6) serious thoughts of suicide; 7) suicide attempt; or 8) being prescribed medication for any psychologicaUemo- tional problem. The composite score of critical items includes symptom reports in the last 30 days, and not lifetime symp- toms. Subjects are also asked how many out of the past 30 days they had experi- enced psychological problems, to rate sub- jectively how much these problems troubled them, and how important treat- ment is for these problems. These items are also included in the PCS. The interrater intraclass correlation for the AS1 psycho- logical composite score was 0.90.

Data Analysis

The point-biserial correlation between the presence of any current psychiatric di- agnosis and the AS1 PCS was first calculated. Then, having established a signrficant rela- tionship between the PCS and a current psychiatric diagnosis, a multiple regression analysis was performed to determine the contributions of the presence of mood, psychotic, anxiety, and somatoform disor- ders to the PCS while controlling for the effects of substance abuse. Because sub- stance abuse can influence psychiatric symptoms, it was important to account for the variance contributed by substance abuse and its comorbid effects on mental illness. To that end, two additional vari- ables were entered into the equation; one represented the presence of any substance diagnosis and the other represented the presence of a current dual diagnosis of mental illness and substance abuse. Finally, correlations between individual items of the PCS and the depression, psychosis, anxiety, and somatoform disorders were calculated.

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RESULTS

There was a signrficant correlation between any current SCID psychiatric diagnosis and the PCS (I,,,, = 0.22; P < 0.001). Of note, the distribution of the groups was highly skewed; 345 patients (95%) had a mental disorder, potentially rendering this a con- servative estimate of the magnitude of the correlation.

Having many subjects with a psychiat- ric diagnosis and so few without presum- ably causes a restriction in the variance of possible PCS values, which would lower the rpb value. Therefore, the square of r*, a measure of the percentage of variance in the PCS accounted for by psychiatric diag- nosis, would also appear lower.

Table 1 shows the number and types of current psychiatric disorders diagnosed in the sample. The overall regression equa- tion of mood, psychotic, anxiety, and soma- toform disorders on the PCS yielded a value ofR = 0.35 (P < 0.01). The equation also included the presence of a current psychoactive substance use disorder and a current dual diagnosis of mental illness and substance abuse to hold constant the variance attributable to these diagnoses. The presence of mood and anxiety disor- ders were independently related to the PCS. (For mood disorders, p = 0.12, P = 0.0011; for anxiety disorders, p = 0.0898, P = 0.0155; [p values represent the un- standardized coefficient values]). Psy- chotic and somatoform disorders showed no significant contribution to the PCS.

Because we are testing many individ- ual correlations, the potential exists that some correlations may be significant by chance. In order to correct for this possibil- ity, we first used the omnibus null test recommended by Cohen and Cohen." The result of the omnibus null test was x211201 = 410; P < 0.05. This finding allowed us to test individual items in the matrix, reduc- ing concern about Type I error.

Table 2 shows the correlation of

I

TABLE 1. Number and percentage of patients in each diagnostic category

Diagnostic Group n Percent

Mood disorder 220 60 Psychotic disorder 137 38 Anxiety disorder 50 14 Somatoform disorder 5 1

Psychoactive substance use disorder 212 58

Mental disorder and psychoactive substance use disorder 195 53

Note: Column of percentages exceeds 100% I because categories are not mumdy exclusive.

individual PCS items with each diagnostic category. Our first organizational approach to these data examined the correlation of each PCS symptom to each psychiatric di- agnosis (see columns of Table 2). In this vein, seven items were significantly corre- lated with the presence of any psychiatric disorder: 1) the presence of anxietyhen- sion; 2) hallucinations; 3) trouble thinking and remembering; 4) taking medication; 5) increased number of days of problems; 6) increased feelings of being troubled by problems; and 7) importance of treatment.

A depressive disorder was sigmficantly associated with the presence of depres- sion, anxietyhension, hallucinations, suici- dal thoughts, suicide attempts, increased number of days of problems, increased feelings of being troubled by problems, and importance of treatment.

A n anxiety disorder was associated with reports of anxietyhension, trouble thinking and remembering, suicidal thoughts, suicide attempts, increased number of days of problems, and in- creased feelings of being troubled by prob- lems, but not with depression, taking medication, or importance of treatment.

The presence of a psychotic disorder was positively correlated with reports of hallucinations and taking medication and negatively correlated with reports

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TABLE 2. Correlations of individual items of psychologid composite score (PCS) of the Addiction Severity Index (MI) with the presence of SCID DSM-111-R psychiatric rJ.iagnoses

PCS Question M Y (relevant to 30 days Psychiatric Psychotic Anxiety Somatoform before interview) Disorder Depression Disorder Disorder Disorder Depression 0.085 1 0.2237**** -0.1392** 0.0819 0.0475 ArudetyKension 0.1759*** 0.1135* -0.0350 0.1669*** 4.0034 Hallucinations 0.1185* 0.1044* 0.2305**** -0.0292 0.0521 Cognitive problemsa 0.1310*** 0.0877 0.0140 0.1231* 0.0719 Violence 0.0390 0.0114 0.0042 0.0627 -0.0194 Suicidal thoughts 0.0840 0.3102**** -0.2869**** 0.1371** O.Oo90 Suicide attempts 0.0320 0.1825*** -0.2029*** 0.1637** -0.0300 Taking medication 0.1491** -0.0477 0.2381**** -0.0350 -0.0032 Number of days of problems 0.1308** 0.2346**** -0.0562 0.1577** 0.0973 Troubled by problems 0.2118**** 0.2678**** -0.1017* 0.1570** 0.0699 Importance of treatment 0.1642** 0.1882*** -0.0492 0.0807 0.0565

I *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. "'Trouble understanding, concentrating, or remembering."

of 1) depression; 2) suicidal thoughts; 3) suicide attempts; and 4) feelings of being troubled by problems. Somatoform disor- ders were not correlated with any of the items. However, because the number of subjects with somatoform disorders was very small, the robustness of the correla- tions of the individual PCS items with this diagnosis is questionable.

An alternative approach to these data examines the correlation of each psychiat- ric diagnosis to each PCS symptom (see rows of Table 2). From this perspective, it is interesting to note that trouble con- trolling violent behavior did not correlate with any disorder. On the other hand, the presence of depression, suicidal thoughts, and suicide attempts correlated positively with depression and negatively with psy- chotic disorders.

Being troubled by problems was posi- tively correlated with anxiety and depres- sive disorders and negatively correlated with psychotic disorders. Overall, no single item was significantly associated in the same direction with all disorders. Further- more, each set of disorders had a distinctive profde of significant correlations, although,

as expected, depressive disorders and anxi- ety disorders were more similar to each 'other than to psychotic disorders.

DISCUSS I ON

Overall, the presence of groupings of a current SCID diagnosis of a DSM-111-R men- tal disorder was highly correlated with the As1 PCS, independent of a substance abuse diagnosis. The PCS may thus have utility for screening patients presenting for sub- stance abuse treatment who need psychiat- ric services.

Specifically, current mood and anxiety disorders, and not psychotic disorders, were found to be significantly related to the PCS. However, this finding may not detract from the utility of the PCS in sub- stance abuse treatment settings because the prevalence of anxiety and depressive disorders has been found to be higher than that of psychotic disorders in substance- abusing patients. 15,19

Individual PCS items and item clusters may be more useful than the PCS itself as a screen for identifying patients with current mental disorders. The substance abuse

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The AS1 and Mental Illness

1 1 '

professional working in a busy clinical set- ting conducting an AS1 interview will pmb- ably not have access to an automatic calculation of the PCS.

Furthermore, no individual item on the PCS was sigm6cantly correlated with all mental disorders, and certain items appeared to be better screening questions for spe- cific subgroups of mental disorders than for others.

For example, patients reporting de- pression and suicidality should be immedi- ately evaluated for a depressive disorder. Patients reporting anxiety/tension and suicidality without depression require evaluation and may be more likely to have an anxiety disorder. Patients reporting hal- lucinations and taking medication should be immediately flagged for a psychotic dis- order evaluation. In an individual reporting hallucinations and receiving medication, the absence of depression or feeling trou- bled by symptoms should not deter the clinician from making a psychiatric referral.

Although these results may not seem surprising, they provide validation of the utility of the AS1 psychological problems section. Although the AS1 PCS cannot sub- stitute for a full psychiatric evaluation or a SCID interview, these data suggest the pos- sibility that the brief set of PCS questions can assist substance abuse professionals- many of whom have little training in mak- ing non-substance-abuse diagnoses-in identifying patients with subgroups of psy- chiatric disorders. Responses and sets of responses to individual AS1 PCS items can alert the interviewer to recommend an in- depth psychiatric evaluation.

This study has several important limi- tations. It was conducted in a mental health inpatient treatment setting, which resulted in certain advantages and disad- vantages in testing the utility of the PCS in substance abuse treatment settings. The high base rate of psychiatric diagnoses fa- cilitated the examination of the correlations of PCS items with individual diagnoses.

Also, diagnoses were made systematically and had high reliability On the other hand, it is possible that the psychiatric problems and profiies of individuals presenting to substance abuse facilities may not be com- parable to the psychiatric problems pre- sented by inpatients in this sample. An important next step would thus be to de- termine whether these findings are repli- cated in patients presenting for substance abuse treatment who receive similar thor- ough psychiatric evaluations.

Another consideration is the intluence of substance abuse on the presentation of psychiatric symptoms. Research evaluations were conducted when the clinical condi- tion of patients had stabilized, which was generally several weeks after admission.

Furthermore, the regression analysis at- tempted to control for transient, substance- induced symptoms by entering the presence of a substance abuse disorder and the dual diagnosis of substance abuse and a mental disorder into the equation. If symptoms per- sisted beyond that point, it could be argued that a psychiatric evaluation is warranted, given the chronicity of the symptoms.

In summary, these findings suggest that the psychological composite score of the AS1 and selected constituent items have utility for helping the substance abuse pro- fessional identify patients who should be referred to a mental health professional for a diagnostic evaluation. More work is nec- essary to bridge the clinical, research, and services gap that divides knowledge about substance abuse and mental disorders.

The authors gratefilly acknowledge the contribution of Dr. Anthony Lehman for his support and comments.

This study was supported by National Institute of Drug Abuse Grant ROI -DA05114 and by National Institute of Mental Health Grant K20-Mn01250-02.

The study waspresented at the 148th meeting of the American Psychiatric Asso- ciation in Miami, FL, on May 24, 2995.

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