Our results, based on a nationally representative sample of HIV patients in care, suggest that providers should be more aware of the potential for comorbid depression in HIV-infected patients, particularly among those with less than a high school education.
Over a third (37%) of our sample was depressed based on a structured clinical interview (CIDI). This prevalence is higher than reported frequencies of primary care patient populations (14%)39
and similar to the frequencies reported for patients with serious medical conditions including post-myocardial infarction, cancer, or stroke/transient ischemic attack (33%–39%).38–42
Yet we estimated that only 46% of depressed patients in our sample were recognized as depressed by their health care providers. This finding is similar to the results of previous research in general medical patient populations16,17,19
that reported that less than half of depressed patients were recognized as depressed by their providers.
Our results suggesting an association between less education and depression underdiagnosis are consistent with previous research.22
We believe that there are 2 primary clinical implications in regard to this finding. First, patients with low education also may have a lower health literacy, particularly “mental health literacy,” which refers to the knowledge and beliefs about mental disorders that would aid in the recognition, management, and prevention of mental illness.43,44
For example, patients with less education may not consider their depressive symptoms as signs of a potentially serious illness warranting treatment. Second, both limited education and low health literacy have been shown to be associated with poorer treatment adherence.45,46
Some providers might hesitate to initiate depression treatment for their less-educated patients if they assume that they are less likely to adhere to such treatment.45
We were surprised to find that compared to patients with private health insurance, those with Medicare as their primary insurance were less likely to have their depression underdiagnosed. This association was not explained by a greater provider contact (number of visits). Perhaps Medicare, seen more as an “entitled” public health insurance program than Medicaid, might prompt providers to recognize and treat symptoms. Moreover, Medicare providers might be more attuned to the needs of patients with chronic conditions and aware of national guidelines for depression screening and treatment. In contrast, patients with private insurance might be well off enough to afford private psychotherapy or counseling outside of their physicians, and such care might not be recorded by their medical providers.
When we repeated the analysis on a larger sample that screened positive for depressive symptoms based on the CIDI-SF, we also found that patients whose providers who typically see fewer than100 HIV-infected patients were less likely to have their depression diagnosis missed in the medical record. Perhaps providers with a lower HIV patient load provide more comprehensive care to a more diverse patient mix, and hence, might be a part of a team-based comprehensive care service and are subsequently more aware of depression screening and treatment guidelines. Such practices also might have services to assist their patients in applying for public insurance coverage such as Medicare. Although we were not adequately powered to examine correlates of depression diagnosis by practice features (e.g., Ryan White–funded clinics), the impact of clinic, health plan, and payer (e.g., Medicare, Ryan White) characteristics warrants future investigation.
We also were surprised to find little association between age and race with underdiagnosis of depression based on the full-length CIDI after adjustment. Yet in the CIDI-SF sample, the association between age (26 and older) and region (Midwest and South) and depression underdiagnosis remained after adjustment. Our results based on the full-length CIDI, while not statistically significant after adjustment, also suggest these trends. Although occurring less frequently in older patients, depression has been found to be under-recognized in older patients in previous studies.18
Perhaps providers of older patients and those from the Midwest or South assume that the depressive symptoms are attributed to HIV or other medical conditions.
The results from the CIDI-SF sample provide additional clues regarding the patient and provider characteristics associated with depression underdiagnosis. Nonetheless, we preferred to emphasize the results based on an established DSM-IV–based diagnostic tool (e.g., CIDI), in order to rule out any ambiguity due to depressive symptoms that might be attributed to alternative causes such as medical comorbidity or substance use, which are usually ruled out with a full structured interview (e.g., full-length CIDI). Moreover, in the HCSUS sample, the positive predictive value for depression based on the CIDI-SF was 0.41 compared to the full-length CIDI,34
suggesting that a number of patients screening positive on the CIDI-SF might not be considered depressed based on a structured clinical interview. The potential trade-off with using the full-length CIDI sample is a smaller sample size because a greater number of patients screened positive for depressive symptoms based on the CIDI-SF. Hence, we had less power in the full-length CIDI sample to reject the null hypothesis. However, the similar findings for education, insurance, older patients, and those living in the Midwest or South suggest that greater attention to the potential adverse impact of unrecognized depression is warranted for these groups.
Despite the important treatment implications of assessing depression underdiagnosis, findings from this study need to be interpreted with caution. First, patients may have been receiving care for depression without the knowledge of their provider, or the provider may have failed to document depression despite knowledge of the condition. Some clinicians have deliberately substituted an alternative diagnosis (e.g., fatigue) for a depression diagnosis, because of the potential for a psychiatric diagnosis to jeopardize reimbursement or patient benefits.47
Nonetheless, we studied a nationally representative sample of patients receiving care for recognized HIV infection, and the insurance ramifications of a depression diagnosis might be a moot issue within a patient population with recognized HIV infection. In addition, we did not examine antidepressant medication use and hence may have missed patients whose providers treated depressive symptoms yet did not record a formal diagnosis. Still, this failure in documentation may reflect a lack in the quality of depression care. Although the consequences for the patient in these cases are less severe than complete failure to diagnose, these represent significant diagnostic failures in themselves.
The underdiagnosis and subsequent undertreatment of depression may result in a number of adverse outcomes, including significant preventable psychiatric morbidity, poor treatment adherence,23
and functional decline.25
Depressive symptoms have consistently been found to be associated with poorer adherence to treatment across several chronic diseases,26–28
including HIV infection.23
Among general medical populations, both major and subthreshold depressive disorders have been found to be associated with cognitive impairment, greater morbidity,19,25
Evidence suggests that the undertreatment of depression is also common among HIV-infected patients,49–51
and in particular, older HIV-infected individuals.52
For HIV-infected patients, some providers often assume that depressive symptoms are the inevitable reaction to the HIV diagnosis or HIV dementia,52
or may have little time to manage the depression due to competing acute medical problems associated with HIV infection.53
Untreated depression in HIV-infected patients may lead to self-medication with alcohol, drugs, or with alternative therapies such as St. John's Wort, which can reduce the blood level of the protease inhibitor indinavir.54
Hence, greater efforts are needed to identify and treat HIV-infected patients with depression. The United States Preventive Services Task force has recommended screening patients at elevated risk for depression, including those with chronic illnesses such as HIV infection.55
When coupled with provider feedback and treatment protocols, screening for depression can improve outcomes for these patients.55
Moreover, research has shown that treatment of co-occurring depression with antidepressant medication56
is effective and can improve health outcomes for many patients with HIV infection.58,59
Therefore, strategies for reducing underdiagnosis of depression, including the use of standardized screening instruments at clinic visits38,55
are needed to increase effective detection and treatment of depression in HIV clinic settings.