Although a common condition in the general population, major depressive disorder (MDD) is even more prevalent among patients receiving medical care. Its early recognition and successful treatment have significant implications in all fields of medicine, and the predominant burden of treatment falls on primary care providers (PCPs). The prevalence of MDD over 12 months is about 6.6%; lifetime risk is about 16.6%. 1,2 About 50% of depressive episodes are rated severe or higher level. Of those having a depressive episode lasting 1 year, only 51% will seek medical help, and only 42% of these will receive adequate treatment. 3 The illness is present across cultures and socioeconomic strata, although the actual rates vary. Women have about a 2-fold higher rate of MDD than do men. 4
The illness can vary from mild to severe. Primary care providers usually provide treatment for patients who are at the mild-to-moderate end of the spectrum; more severely ill patients are likely to require consulting with mental health specialists. Patients who have 1 episode of MDD have a 50% chance of having a second episode during their lifetime. After a second episode, the risk of another episode rises to about 80%. 5 After a third episode, it is presumed patients will continue to have subsequent episodes, because the risk rises to 90%. Among patients with MDD, about 35% will have a chronic, relapsing pattern of illness. 6 Because of a relative shortage of specialty mental health providers in many areas served by federal practitioners, it is important to maximize the impact of a patient’s primary care team in treating this common and persistent illness.
Morbidity from MDD includes dysfunction in all spheres of life: Difficulties with work, home life, self-care, medication adherence, and mental health are all encountered. Although a minority of patients with depression will attempt or complete suicide, depression is a major predictor of suicide risk. However, it is a modifiable risk factor with successful treatment. Among the general population, the reported risk of suicide is about 11.5 per 100,000 per year. 7 Among patients with psychiatric illness, the rate is higher.
Many patients treated through the federal system have been identified as having a risk of suicide higher than that of the general population. These populations include veterans (41% to 61% above the national average); Native Americans aged 18 to 24 years (about 2 to 3 times the national average); and active-duty military (18.7 per 100,000 per year, 50% above the national average). 8-10
Diagnosis
Several subtypes of MDD and associated depressive disorders exist. The diagnosis requires a constellation of criteria for diagnosis. Using the full criteria to make an MDD diagnosis may seem excessive, but its use is critical to guide sound treatment decisions (ie, past presence of manic or hypomanic episode, which would signify bipolar disorder, or psychotic symptoms that would dictate a different path and a referral to a psychiatrist). For example, an antidepressant given to a patient with a history of hypomania or mania can trigger a full manic episode with all the potential morbidity that mania entails. The presence of psychotic symptoms leads down a different treatment path that requires antipsychotic medication.