Assessment and Diagnosis of Depression
The mental health condition commonly referred to as “depression,” is typically and abrreviation for major depressive disorder, although other unipolar depressive disorders also exist. The current edition of the Diagnostic and Statistical Handbook of Mental Disorders (DSM-5) requires that at least five out of nine symptoms including depressed mood or loss of interest/pleasure must be present every day for a minimum of two weeks (American Psychiatric Association, 2013). Other possible symptoms include weight changes, increase in purposeless movement or slowed movement, decreased energy or fatigue, feelings of worthlessness or guilt, impairment in cognitive functions such as concentration and decision-making, and suicidal ideation Association, 2013). The DSM-5 also includes seven severity/
course descriptors for greater diagnostic specificity (American Psychiatricd Association, 2013). Two descriptors indicate degree of recovery (if any), three are severity indicators, one notes if psychotic features accompany depressive symptoms, and the last is denotes unspecified depression. Each of these descriptors is assigned a unique diagnostic code. Nine additional specifiers paint a more detailed picture about a particular patient’s illness, such as whether the depression has a seasonal pattern, occurred after childbirth, or is accompanied by catatonia, anxiety, or manic symptoms. There is no limit to the number of latter specifiers that can be applied to a major depression diagnosis (American Psychiatric Association, 2013).
Seemingly paradoxical symptoms subsumed under one diagnosis may lend themselves to diagnostic inaccuracy. For example, a healthcare provider unfamiliar with diagnostic criteria may evaluate an otherwise depressed
patient who brightens when given a compliment and fail to recognize their depression. In fact, this is an example of mood reactivity—which may present as a feature of depression.
Diagnosing depression:Difficult task that requires special knowledge and training
Many people in need of relief from depressive symptoms may never receive evaluation or treatment by a qualified mental health provider.
This is problematic given that mental health diagnoses assigned by primary care providers have a high likelihood of inaccuracy.Subscribe
~ 60% of patients
Receive treatment for depression through their primary care provider.
But he may have little or no training in assessing mental disorders.
~ 80% of prescriptions for antidepressants
Discharged by primary health care providers.
One study comparing initial diagnoses by referring primary care providers to the diagnoses of consulting psychiatrists found that primary care providers diagnosed depression correctly only 50% of the time. A meta-analysis conducted by Mitchell and colleagues (2009) found that primary care
demonstrated an overall diagnostic accuracy of approximately 47%, with about 50% accuracy in identifying a depressed patient (sensitivity), and 81% accuracy in correctly identifying when the patient did not qualify for a diagnosis of depression (specificity).
Methods of Assessment
Along with various types of clinical interview (unstructured, semi-structured, and structured), self-report measures are currently used in depression screening and to aid in diagnosis.
Prone to response bias as well as bias on the part of the clinician interpreting the available data
- including low cost
- minimal time constraints
- ease of administration and interpretation
The Beck Depression Inventory-II BDI-II
is one commonly used self-report measure
Comprised of 21 items, it measures symptoms of depression for the most recent two-week period and is intended for use in both normal and psychiatric populations (Smarr & Keefer, 2011). Each item is rated for severity on a scale of 0-3, zero indicating the absence of the symptom and three indicating extreme severity. The recommended ranges for interpreting overall scores are 0-13 (minimal depression), 14-19 (mild depression), 20-28 (moderate depression), and 29-63 (severe depression). Determining sensitivity and specificity for this measure is a bit challenging, as different cutoff scores are recommended for different groups of patients (e.g., those with different comorbid medical diagnoses) to achieve optimal levels of accuracy. Therefore, these score ranges may not be all-encompassing in their applicability to various populations (Smarr & Keefer, 2011). However, in general, a review of the literature reported sensitivity at approximately 70% (Wang & Gorenstein, 2013) In addition to the absence of a universally applicable cutoff score, other limitations of the BDI-II include problems with establishing the validity of this measure across cultures. While the BDI-II has been translated into several different languages, insufficient evidence exists to fully support cross-cultural comparability (Wang & Gorenstein, 2013).
The Patient Health Questionnaire-9 PHQ-9
is one commonly used self-report measure
It is a 9-item scale that also provides item scores ranging from 0-3. However, unlike the BDI-II , these subscores indicate frequency of symptoms—not at all to nearly every day (Kroenke et al., 2001). When compared to scores on a structured interview, sensitivity was 74% and specificity was 91% with a cutoff score of 10 (Huba et al., 2014). which is a higher score than originally recommended by the test developer (Spitzer et al., 1999; as cited in Huba et al., 2014). Huba and colleagues also found that 25% of patients who met criteria for a depression diagnosis through the PHQ-9 did not qualify for this diagnosis when assessed with the BDI, an earlier version of the BDI-II. Similarly, another study comparing PHQ-9 and BDI-II scores found a 77% correlation between overall scores (Kung et al., 2013).
As these data demonstrate, limitations associated with currently used measures of assessment include lower than desirable correspondence between measures, challenges posed by language and culture, and the potential for exaggeration or minimization of symptoms.