Cognitive Correlates of Job Tenure Among Patients With Severe Mental Illness

These data were collected at the Baltimore site of the Employment Intervention Demonstration Project. This eight-site project was designed to examine the efficacy of several approaches to vocational rehabilitation for patients with severe mental illness. The Baltimore site investigated the comparative efficacy of the individual placement and support model, developed by Drake et al. (17), versus the current service model, which emphasizes a continuum of transitional and supported employment services. The study involved random assignment of patients to rehabilitation conditions, with long-term assessment of vocational and nonvocational outcomes.

The individual placement and support model emphasizes the integration of vocational and clinical services with the goal of rapidly achieving competitive employment, bypassing many of the prevocational activities common in rehabilitation programs. Unlike the traditional models of vocational rehabilitation, individual placement and support require that the employment specialist, psychiatrist, and case manager be part of the same service team and share in decision making. The employment specialist, client, and treatment team then develop an individualized approach geared directly toward rapidly achieving competitive employment. The individual placement and support model seeks employment opportunities that are consistent with the clients’ preferences, skills, and abilities. Working with small caseloads, the individual placement and support specialist is available to focus on rapid job search and placement and provide continued follow-up support. (For a complete description of the individual placement and support model, see Bond et al. and Drake et al. [18, 19]. A complete description of study methods and results from the Baltimore site is found in Lehman and colleagues [20].)

The study group consisted of 150 patients in the Employment Intervention Demonstration Project who completed the neuropsychological assessment and received psychiatric care from one of three continuous-care teams or a general outpatient clinic within a university-run community mental health agency that serves inner-city Baltimore. The population of this catchment area is predominantly African American and lower income. The total Baltimore Employment Intervention Demonstration Project study group of 219 patients was randomly selected from the roster of all patients currently receiving psychiatric care in this treatment system. These care teams provide a comprehensive array of outpatient/inpatient services, including substance abuse, mobile, and assertive community treatment. The majority of the subjects, 68% (N=102), were drawn from the assertive community treatment and mobile treatment teams that provide care for the most severely disabled patients.

Study inclusion criteria required that subjects be receiving psychiatric-disability-based income support or have a diagnosis of schizophrenia or schizoaffective disorder. Patients could also qualify if they had an extensive prior hospitalization history (requiring two or more psychiatric hospitalizations of >21 days for any psychotic or mood disorder over the previous 3 years at least 42 days prior to a current hospitalization or 90 or more total days in a psychiatric or nursing home during the past 3 years). In addition, patients not meeting either of the first two criteria could also enter the study if they had a history of mental disorder lasting for at least the past year, during which they were unable to spend at least 75% of their time in some gainful activity because of a mental disorder. All patients had to have been unemployed for a minimum of 3 months before study entry.

As part of study participation, subjects underwent an extensive baseline clinical psychiatric evaluation, including the Structured Clinical Interview for DSM-IV Axis I Disorders, Patient Edition (21), that was combined with medical records and clinical reports to establish a research diagnosis. Participants were approached to participate in the neuropsychological testing after completion of the baseline assessment; 150 of 219 patients consented to participate. Patient decision, failure to keep multiple scheduled appointments, and the fact that the Employment Intervention Demonstration Project recruitment period extended slightly beyond the period when testing personnel were readily available explain the difference between the number of subjects with cognitive data versus the entire Baltimore Employment Intervention Demonstration Project study group. Since the tested (N=150) versus nontested (N=69) groups did not differ significantly on multiple baseline demographic characteristics (including age, years of education, distribution of diagnosis, or past work history), it appears likely the results from the tested group generalized to the entire study group.

After study entry, the vocational status (job start dates, job end dates, salary, hours worked, benefits, level of mainstream integration) of the subjects was documented on a weekly basis throughout the 24-month follow-up period. In the event that participants withdrew from the study or were lost to follow-up, their last vocational observation (which in every instance was unemployment) was carried forward. The analyses reported were based on the total number of hours worked by the 12-month and 24-month follow-up time points.

The majority of the study group, 74% (N=111), had a diagnosis of psychotic disorder, 91% (N=101) of whom were diagnosed with a schizophrenia spectrum disorder. The remaining 26% (N=39) of the study group received a mood disorder diagnosis (most often bipolar disorder). The mean age of study participants was 39.8 years (SD=8.2). Approximately half (48%, N=72) of the study group did not finish high school or receive a General Equivalency Diploma. Only 7% of the study group attended 1 or more years of college.

A minority of the subjects, 25% (N=38), were Caucasian, 65% (N=98) were African American, and 9% (N=14) were of another racial group. There were more men (N=86, 57%) than women (N=64, 43%). The majority of the subjects (N=114, 76%) had a lifetime substance use diagnosis, with problematic use in the last year evident in 53% (N=79) of the study group. The study group also demonstrated significant long-term functional disability. The majority of the subjects, 90% (N=135), were receiving Supplemental Security Income, Social Security Disability Insurance, or both. Participants had been hospitalized on average 12.2 times (SD=9.9). Although most subjects, 95% (N=143), had a lifetime work history, only 68 (45%) had held a job in the last 5 years.

All participation was voluntary, and patients were reimbursed for participating in the Employment Intervention Demonstration Project study and for the cognitive testing. Written informed consent was obtained from all subjects after complete description of the study.

Subjects received a test battery, which typically took 2.5–3.0 hours to complete. The test battery was designed to provide an estimate of general intellectual ability (a WAIS-III [22] estimated IQ was generated from four subtests), language/academic ability (the Wide-Range Achievement Test 3 [WRAT-3] reading subtest [23] and the Woodcock-Johnson listening comprehension subtest [24]), aspects of attention (the Stroop Color-Word Test [25], the Trail Making Test [26], and the Continuous Performance Test [27]), memory (logical memory and visual reproduction subtests drawn from the Wechsler Memory Scale, 3rd ed. [28]), executive functioning and working memory (a 64-card version of the Wisconsin Card Sorting Test [29], verbal fluency, and letter-number span from the WAIS-III), and motor functioning (Purdue Pegboard [30] and Finger Tapping [26] tests). Subjects also completed the Repeatable Battery for the Assessment of Neuropsychological Status (31). Tests were administered and scored as specified in test manuals, with conversions to age-scaled scores or demographically corrected T scores whenever possible. Only 64 cards were administered for the Wisconsin Card Sorting Test, and scoring was modified to give partial credit for number of categories completed if subjects finished the test with three or more items correct in a row.

The data analyses addressed two major questions: 1) are there cognitive differences between patients who did and patients who did not achieve employment? and 2) is cognitive performance related to the extent of employment (defined as number of hours worked) over the follow-up period? To address the first question, we compared the performance of the 40 patients who obtained employment by the 24-month follow-up to the 110 who did not using t tests for individual tests and composite cognitive continuous measures. We did not conduct post hoc corrections for multiple tests since such correction was not necessary.

The analyses for the second question were quite complex because of the distribution of the hours-worked score—the critical study outcome measure. The majority of the subjects worked very few hours (75% [N=30] had worked 415 hours or fewer by the 24-month follow-up), but a small minority worked substantially more. This positive skew resulted in violation of the assumptions of hypothesis tests for Pearson’s correlations and multiple regression techniques. After exploring multiple options, we decided to treat the data in two ways. First, although the data violated the distributional assumptions for Pearson’s correlations, such an analytic approach actually captured the underlying clinical significance of the association. That is, the outliers in outcome were also likely to be the cognitive outliers. Thus, Pearson’s correlations reflected this relationship. However, this approach is open to the criticism that results driven by such observations of outliers may be less likely to generalize to other study groups. Second, in order to attenuate the impact of the outliers, we also performed Spearman’s correlations. This analytic approach was based on the rank ordering of the cognitive test results and the total hours worked and treated both the cognitive scores and the total hours worked as though they were equally spaced from one another. Therefore, Spearman’s results were much less susceptible than Pearson’s correlations to the impact of extreme or outlier values. Insofar as such outliers were present in the observed distribution and that these extreme values were clinically meaningful, Spearman’s results failed to reflect the role of such observations. We present both analytic approaches for the 12- and 24-month follow-up time points to provide a comprehensive description of the data.

The skewed distribution of the outcome variable precluded a multivariate approach to examining the relationship between cognitive functioning and outcome. Specifically, multiple regression models of the relationship of cognition and hours worked resulted in the prediction that certain subjects would work “negative hours”—an impossibility—which suggests that such models could not be legitimately applied to the data. In order to simplify data presentation, we created several composite scores that were derived from tests with multiple conditions after first determining that the composite score behaved similarly to the original tests in terms of relationship to the outcome variables. The three Stroop conditions were averaged, the three Purdue Pegboard conditions were averaged, as were the two Finger Tapping scores, and we averaged the scaled scores from the immediate and delayed recall conditions of the logical memory and visual reproduction subtests to generate overall measures of auditory and visual memory.

A total of 40 study participants (27%) obtained employment over the 24-month follow-up interval, and 33 obtained employment during the first 12-month follow-up. The vast majority of jobs were in the services industry (restaurant, janitorial, etc.). Of these 40 participants, 35 (88%) had been randomly assigned to the individual placement and support condition, and five (13%) had been randomly assigned to standard rehabilitation services. Thus, there was a clear effect of treatment condition, consistent with the findings in the total group, as presented by Lehman et al. (20). The 40 subjects who obtained employment did not differ from the 110 who did not obtain employment on multiple demographic features, including age, distribution of ethnicity, gender distribution, education history, psychotic diagnosis, age of first hospitalization, or substance abuse (history or current). A complete analysis of the role of demographic factors is presented in the main report for the total study group and was not undertaken here in this subgroup.

The participants who obtained employment worked an average of 214.79 hours (SD=268.73) by the 12-month follow-up; the average had increased to 388.37 hours (SD=486.93) by the 24-month follow-up. As noted, the distribution of hours worked was skewed (similarly at both follow-ups; only the 24-month data are described in detail). Quartiles for total hours worked at the 24-month follow-up were as follows: first quartile: total=1–36 hours, second quartile: total=37–135 hours, third quartile: total=136–415 hours, fourth quartile: total=416–2,425 hours. Patients in these quartiles worked the following average number of hours: first quartile: mean=19.50 hours, second quartile: mean=87.00 hours, third quartile: mean=260.10 hours, fourth quartile: mean=942.70 hours. Thus, the bottom 75% of the group all worked less than 415 hours, and an average of 122.20 hours was worked by the group. The average number of hours worked by the top quartile was nearly eight times higher than the mean worked by the bottom 75% of the workers.

The mean performance of the 40 patients who obtained employment on the major cognitive variables is shown in Table 1. The overall group demonstrated marked cognitive impairment relative to the performance of test standardization samples, with multiple scores approximately two standard deviations below the normal mean. It appears that much of the impairment in this group stemmed from early in development, as seen in the poor performance on measures of academic skill (WRAT-3 reading), expressive vocabulary (WAIS-III vocabulary), and receptive vocabulary (Woodcock-Johnson listening comprehension). Measures of basic academic and language skills are typically considered to be markers of premorbid competence (32). Thus, it is likely that the overall level of impairment documented in this group represents a combination of premorbid and illness-onset-related deficits.