Schizophrenia diagnoses confounded by race

Gara AM. Arch Gen Psychiatry. 2012;69:593-600.

  • June 18, 2012

Black patients were more than twice as likely to be diagnosed with schizophrenia as non-Latino white patients, according to new data.

“In the United States, African American individuals in clinical venues are disproportionately diagnosed with schizophrenia compared with white individuals,” the researchers wrote.

Michael A. Gara, PhD, and colleagues gathered data on patients aged 16 to 45 years who self-identified as black (n=241), non-Latino white (n=220) and Latino (n=149). Patients were included in the study if they exhibited significant affective symptoms.

Gara and colleagues collected patients’ medical records from six US clinical settings. At each site, trained clinical interviewers completed the Diagnostic Interview for Genetic Studies and additional questionnaires for each patient. The medical records and interview transcripts were sent to the University of Cincinnati, where editors deleted all references to people, names, places and linguistic idiosyncrasies, phrasing or syntax that might signal to ethnicity. The redacted material was then distributed to two independent diagnostic experts — masked to the study —  who rated patients’ symptoms and diagnoses through consensus.

The researchers used logistic regression models to determine whether higher rates of schizophrenia in blacks would continue after controlling for a number of confounding variables, including blinded expert diagnoses of serious affective illness.

Results show that black patients were significantly more likely to be diagnosed with schizophrenia than non-Latino white patients (OR=2.7; 95% CI, 1.5-5.1). Similar differences in diagnoses between black patients and white patients occurred when schizophrenia was “more broadly defined,” according to researchers (OR=2.5; 95% CI, 1.4-4.5). The effect did not extend to Latino patients. Black patients did not differ significantly from white patients in overall severity of manic and depressive symptoms, but black patients exhibited more severe psychosis.

The researchers concluded that psychotic symptoms in black patients may be overvalued by clinicians, skewing diagnoses toward the schizophrenia-spectrum, even if the severity of black patients’ symptoms is the same as that of white patients.

“The results strongly support the need for a national approach to enhance quality of mental health care by eliminating disparities in psychiatric diagnoses that occur systematically in this vulnerable population,” the researchers wrote. “Moreover, these results remind clinicians to consistently challenge their own diagnostic assessments, particularly in patients from other ethnic groups or in those who are failing to respond to treatment.”

Disclosure: Refer to the study for a complete list of financial disclosures.

Perspective

  • Diagnostic disparities between African Americans and other racial/ethnic groups have been noted in the literature for many years. The phenomenon of higher rates of schizophrenia and lower rates of affective disorders in African-American patients conflicts with epidemiological survey data, and has always been questioned. There have been attributions of faulty clinical assessment due to clinicians’ ignorance of culturally normative behaviors, or sometimes to racial and ethnic bias.

    The authors point out that prior studies typically occurred at a single clinical site, and more importantly, failed to blind clinicians and researchers to their subjects’ race/ethnicity. Their study therefore made multi-ethnic comparisons in six clinical sites in the U.S. using assessments both blinded and unblinded for ethnicity. They also included a Latino population to determine whether minority status was a factor, controlling overall for age, sex, income, site and education. This was an extremely well-designed study with carefully trained interviewers at each site and numerous relevant controls, with no significant demographic differences among the three ethnic groups. Medical records and transcripts excluded any racial/ethnic cues and were assessed by independent diagnostic experts.

    The authors of this study emphasize the serious implications of misdiagnosis for people’s lives, both in treatment and prognosis. They urge clinicians to consistently challenge their diagnostic assumptions about patients from other ethnic groups, particularly those who fail to respond to treatment, while agreeing that significant improvement in diagnosis is unlikely to occur until objective biological markers for specific conditions are identified.

    • Harriet P. Lefley, PhD
    • Professor, Department of Psychiatry and Behavioral Sciences
      University of Miami Miller School of Medicine
  • Disclosures: Dr. Lefley reports no relevant financial disclosures.

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