Among Blacks and Whites with co-occurring substance use disorders and mood or anxiety disorders in a general population sample, the results indicated differential lifetime patterns of service utilization for psychiatric and substance use disorders. Specifically, among individuals with these comorbidities, Whites were more likely to receive services for mood and anxiety disorders than Blacks. This overall pattern of results held across types of service use for mood and anxiety disorders, including outpatient treatment and taking medication.
The large sample size of the NESARC enabled us to control for several clinical, socioeconomic, demographic and geographic covariates, an important advantage of the current study. Importantly, the differential lifetime patterns of mental health service utilization held even after adjusting for these variables. For example, there are differences in the racial/ethnic makeup of regions in the United States (http://www.census.gov/population/www/cen2000/phc-t6.html
, accessed 10/03/07). These differences were reflected in the subset of the NESARC sample with co-occurring disorders described above. Because we controlled for region in the logistic regression models, we were able to show that differential patterns of mental health treatment persisted despite regional differences. In addition, it is of particular interest that disparities in mental health treatment persisted despite controlling for income, as several past studies have indicated that racial/ethnic differences in some mental health service use are substantially attenuated by socioeconomic status differences Val, add reference for Mojtabai and Padgett to this sentence (listed below).33
Our results suggest that while income may mediate racial/ethnic differences to some extent, the entire findings on disparities cannot be fully explained by this factor.
In demonstrating that comorbid Blacks underutilize mental health services for mood and anxiety disorders compared with comorbid Whites, this study extends prior research indicating similar disparities among Blacks with mood and anxiety disorders that did not focus specifically on individuals with co-occurring disorders. 3;28;30;33
The present research extends these findings by: 1) demonstrating this effect in a comorbid sample, and 2) by specifically indicating the types of service utilization that are driving this effect. That is, among comorbid individuals with a mood/anxiety disorder, Whites are approximately 3 times more likely to have ever received outpatient treatment or have ever taken medication for their disorder, but no significant or visible differences emerged for the odds of receiving inpatient treatment.
In contrast to service use for mood/anxiety disorders, no Black/White differences were found for alcohol services, while Blacks were more likely than Whites to use 12-step self-help and social services for drug use disorders and more likely to think they should have sought help but did not go. These results contradict the general assumption that Blacks are less likely to utilize any type of intervention.27;31–33
While Keyes et al. (2007, under review) found parallel results in the general population not selected for comorbidity, research with representative comorbid samples examining racial/ethnic differences in specific types of service utilization that included substance use disorders has not been conducted previously. Thus, these findings represent important new information.
To our knowledge, this is the first study to document Black/White differences in service utilization among individuals with co-occurring substance use and mood/anxiety disorders in a general population sample. Given the novelty of these findings, little is known regarding the processes leading to the discrepancies in types of services received. Possible mechanisms could include: differences in the recognition of, and reaction to, externalizing versus internalizing symptoms; racial/ethnic differences in social pressure to enter treatment for different types of disorders,63;64
coercion resulting from drug policies and laws that disproportionately affect Blacks,65;66
and differing conceptions of the causes and treatment of mental health problems among Blacks and Whites.67
Most of these mechanisms, however, have been postulated to account for the global Black/White disparities in service utilization. Consequently, research has not been conducted to discern how and whether these mechanisms explain the persistence of disparities for mental health, but not for substance use, disorders. The results therefore highlight the need for more theory-driven research that addresses why certain mechanisms are associated with disparities in service utilization for some disorders, but not others.
Importantly, the results indicated that regardless of Black/White status, all respondents with co-occurring disorders were less likely to utilize services for substance use disorders than for mood or anxiety disorders. In fact, comorbid respondents were nearly twice as likely to utilize services for mood or anxiety disorders than for substance use disorders. This result parallels patterns of service use found in two recent general population samples, which confirmed that use of mental health services for disorders such as depression is far more common than treatment for substances, both for individuals with independent psychiatric disorders5
as well as co-occurring psychiatric conditions.36
In addition, over a third of all comorbid respondents did not receive services for either disorder. Given the association of comorbidity with many adverse clinical and health outcomes,7,8;16
these results suggest the need for vigorous dissemination efforts to reach individuals with a clear need for treatment services. While the reasons underlying the relative lack of service utilization for alcohol and drug use disorders among comorbid respondents remain unclear, one likely possibility is that efforts to de-stigmatize depression and increase awareness of the illness and its treatment,68;69
which have significantly impacted rates of service use for mood/anxiety disorders,70
have not been successfully implemented in the area of alcohol and drug use disorders.5;6
This represents an important direction for future research aimed at reducing disparities in service utilization for substance use disorders.
The results of the present study suggest several important avenues for future research. First, further studies are needed to determine the individual, cultural, societal, and legal factors that contribute to the Black/White service utilization disparities shown here. Second, there is an urgent need to identify the barriers that prevent individuals with co-occurring disorders from receiving services for substance use disorders at the same rate that they receive services for mood and anxiety disorders. This information is essential in order to better assist prevention and intervention strategies to reduce these overall disparities. Third, studies are needed regarding other important racial/ethnic groups with different cultural beliefs and health utilization issues, such as Hispanics, to determine whether the same disparities are present. Such analyses, currently underway, should help identify similarities and differences in patterns of other ethnic groups. These may help illuminate the processes mediating differences in service utilization between Blacks and Whites in this sample.
Potential study limitations are noted. Recall bias might affect the estimates of lifetime service use, especially among older respondents. To examine this, we re-ran the analyses on past-year services utilization among the subset of respondents with current (past 12 months) disorders. While smaller sample sizes reduced power to detect statistical differences, the overall magnitude and direction of effects did not change, suggesting that recall bias did not affect the estimates. Second, while additional detail on different types and sources of treatment for mood/anxiety disorders would be helpful and should be added to future surveys, differences in questions regarding mood/anxiety service use and alcohol/drug service use reflect true differences in both the services and service delivery systems for these disorders. Third, the study did not assess differences in treatment adequacy between the comorbid Black and White respondents. Questions of treatment adequacy involve a related but different research focus than the one motivating the present study. This issue therefore represents an important avenue for future research. Finally, these data were cross-sectional. Prospective investigation of factors predicting treatment entry would be valuable, and can be conducted when NESARC three-year follow-up data become available.
Two potential limitations concerning sampling of Blacks in the NESARC also warrant discussion. First, individuals institutionalized throughout the period of data collection were not included in the NESARC, possibly underestimating service utilization among Blacks, who have higher incarceration rates. However, the literature is not consistent regarding whether treatment rates are actually higher for those who are incarcerated: some studies show that racial/ethnic minorities in prison receive fewer mental health services,71;72
while other studies do not.73;74
Thus, it is unclear how inclusion of incarcerated Blacks would affect our estimates. Additionally, although data from the recent Census show higher rates of Black incarceration in the United States, 95% of Black men are not incarcerated, suggesting that our results can be generalized to the vast majority of Blacks with co-occurring disorders. Nevertheless, more research on racial/ethnic differences in service utilization among those not available for general population surveys is warranted in order to address whether Black incarceration biases our findings.
Second, some research has indicated that Blacks are over-represented in inpatient mental health treatment programs. If Black respondents were more likely to be excluded from the survey because of inpatient treatment, then a bias could be introduced into our results. This prospect is unlikely, however, because respondents would need to have been in an inpatient facility for two years (the entirety of the data collection period). Every effort was made to interview selected respondents after temporary institutionalization, so it is unlikely that our effect estimates were biased due to differential long-term institutionalization for a mental health condition among Blacks compared to Whites. Further, some studies in the U.S. have shown that Blacks are not overrepresented in inpatient mental health treatment. Thus, it is unclear that the potential for such a bias is present.
The study had considerable strengths that extend our knowledge about Black/White disparities in service use in several important ways. First, the general population data overcome biases inherent in convenience samples recruited from treatment clinics, including generalizability and low power to detect effects, and therefore represent an important advantage of the present study. Second, the size of the NESARC overall allowed defining an unprecedentedly large subset of Blacks and Whites with co-occurring psychiatric and alcohol/drug disorders (N=4,250) that allowed examination of whether Blacks receive less treatment for all psychiatric disorders or only a subset. Sample sizes in previous epidemiological surveys were limited for studying specific types of service use for specific disorders by racial/ethnic groups, particularly among individuals with psychiatric comorbidity.3;30
Third, all individuals who drank or used substances were assessed fully for dependence as well as abuse, avoiding a limitation in other national and international surveys75;76
that skipped assessment of dependence among those with no abuse symptoms, undercounting dependence generally and disproportionately among women and minorities.77–79
Thus, the present study provides a statistically powerful investigation of Black/White differences in service utilization among individuals in the general population diagnosed with co-occurring psychiatric conditions.
Racial/ethnic disparities in the American healthcare system have increasingly been a focus of research,80
and the present study represents an important contribution to these efforts. In particular, the study determined that patterns of service use among comorbid Whites and Blacks depend on the type of disorder and service considered. Taken together, the results strongly suggest that steps should be taken to address the specific Black/White disparities in service use for mood and anxiety disorders. Further, as previously mentioned, efforts to de-stigmatize depression68;69
have impacted rates of service use for mood/anxiety disorders.70
The present study adds to the evidence of the need for similar efforts to increase service use for drug and alcohol use disorders among Blacks and Whites alike to diminish the overall disparity in service utilization for drug and alcohol problems compared with mood/anxiety disorders among individuals with co-occurring psychiatric conditions.