Self-Reported Health Status May Predict Response to Depression Treatment

Less than half of patients receiving depression care in primary care responded to treatment, and poor self-rated health was by far the strongest predictor of failure to reach remission or respond to treatment, according to an observational study published July 15 in Psychiatric Services in Advance.

Other predictors of poor response included unemployment and lower income. Conversely, younger age and milder baseline depression severity predicted better response.

The results point to a subset of patients who might be identified for more intensive services, including collaborative care, which can address general and psychiatric conditions, say researchers at several institutions.

“The take-away message of our study is that six-month rates of depression remission or response were only 47 percent in this large population of primary care patients receiving usual care, and those who self-rated their health as poor to fair or who were unemployed were significantly less likely to see their depression improve,” lead author Rebecca Rossom, M.D., of HealthPartners Institute, told Psychiatric News. “Collaborative care can be effective for depression; however, this model can be cost-prohibitive for some care systems. For those systems, it would be more efficient to focus use of this model on patients who are more likely to have poor depression outcomes.”

Outcome data for 792 patients in 83 urban and rural primary care clinics across Minnesota were analyzed. Baseline and six-month data were collected between March 2008 and November 2010, prior to the implementation of collaborative care in these primary care clinics. Patients received usual care for depression in their primary care clinics; all received antidepressants for depression, and some patients were co-managed by psychotherapists or psychiatrists.

The primary outcome was remission or response, with remission defined as achieving a follow-up PHQ-9 score of 5 or less; response was defined as a follow-up PHQ-9 score that was at least 50 percent lower than the patient’s baseline score. A wide range of correlates to treatment response was examined.

At six months, 47 percent of patients achieved a combined outcome of remission (n=292) or response (n=83). Patients who reported fair or poor health were significantly less likely to experience depression remission or response compared with patients with good, very good, or excellent health. Patients who were unemployed or had lower income were also less likely to respond.

Rossom said she believes the overall low rate of depression remission and response in primary care is multifactorial. “We know adherence rates are low, with approximately 30 percent of patients discontinuing antidepressants within one month and 60 percent by three months,” she told Psychiatric News. “In work in the Mental Health Research Network [MHRN], we found race and ethnicity to be the largest predictor of early antidepressant adherence, with most racial and ethnic minority patients less likely to adhere to their antidepressants than white or Native American/Alaska Native patients. This may reflect preference among most racial and ethnic minorities for therapy over medications, but access to psychotherapy is limited, particularly in rural and other underserved communities. It also may reflect intentional nonadherence, with patients discontinuing their antidepressants due to side effects, for example.”

The MHRN is a consortium of public-domain research centers embedded in 13 large not-for-profit integrated health care systems that serve over 12.5 million patients in 15 states, supported by the National Institute of Mental Health.

Additionally, Rossom said, many primary care providers are not seeing patients coming back or do not have support staff checking in with patients within the recommended timeframe for a host of reasons.

Rossom noted that within the study there was a tendency for patients who were also seen by a therapist or psychiatrist to have lower rates of remission/response, but these differences did not reach statistical significance. “So I don’t think we can say there is a true difference there, and even if there was, I would suspect significant selection bias, in that patients referred to behavioral health were more likely to have severe or treatment-resistant depression,” she said. ■

“Predictors of Poor Response to Depression Treatment in Primary Care” can be accessed here.