Doctors for the first time can determine which medication is more likely to help a patient overcome depression, according to research that pushes the medical field beyond what has essentially been a guessing game of prescribing antidepressants.

A blood test that measures a certain type of protein level provides an immediate tool for physicians who until now have relied heavily on patient questionnaires to choose a treatment, said the research lead.

The study demonstrated that measuring a patient's C-reactive protein (CRP) levels through a simple finger-prick blood test can help doctors prescribe a medication that is more likely to work. Utilizing this test in clinical visits could lead to a significant boost in the success rate of depressed patients who commonly struggle to find effective treatments.

The new research published in Psychoneuroendocrinology measured remission rates of more than 100 depressed patients prescribed either escitalopram alone or escitalopram plus bupropion. Researchers found a strong correlation between CRP levels and which drug regimen improved their symptoms:

• For patients whose CRP levels were less than 1 milligram per liter, escitalopram alone was more effective: 57 percent remission rate compared to less than 30 percent on the other drug.

• For patients with higher CRP levels, escitalopram plus bupropion was more likely to work: 51 percent remission rate compared to 33 percent on escitalopram alone.

The lead researcher noted that these results could readily apply to other commonly used antidepressants.

While previous research to establish CRP as an antidepressant marker used levels three to five times higher than the latest study, "my theory was that you don't need that high of an inflammation to experience the sickness of depression," lead author said. "Even a little inflammation may be sufficient for the patients to experience some of these symptoms of depression."

The next step is to conduct larger studies to verify CRP's role with other antidepressants and find alternative markers where CRP does not prove effective.

http://www.utsouthwestern.edu/newsroom/news-releases/year-2017/mar/biomarkers-trivedi.html

http://www.psyneuen-journal.com/article/S0306-4530(16)31052-6/abstract