- A 2-stage strategy, combining an assessment of severity with depression criteria, can help a physician focus on the most severe cases without missing less severe ones that still need treatment (B).
- Because of its brevity, relatively high positive predictive value, and ability to inform the clinician on both depression severity and diagnostic criteria, the PRIME-MD Patient Health Questionnaire (PHQ-9) is the best available depression screening tool for primary care (B).
- One-time screening is cost-effective; physicians may elect to screen more often based on risk factors (A).
What is the most efficient and accurate way for a busy primary care physician to screen patients for depression? Many screening tools exist, but they are not equally effective.
A careful review of the literature strongly favors a 2-stage strategy assessing both depression severity and criteria. In this article, we describe this optimal approach against the background of other available resources.
Health and economic impact of depression
In the average family practice, around 6 cases of depression go unrecognized each week. This real-world estimate derives from studies that consistently report a 10% prevalence of depression in primary care patients1 but a rate of recognition by primary care clinicians of only 29% to 35%.2-4 Depression is a common condition with a large impact on quality of life and productivity, one that indirectly affects other health states, including cardiovascular disease.5-9 It is responsible for an estimated economic cost in the US of over $40 billion annually. As a result, depression screening has been an active area of research, and a variety of organizations have issued guidelines recommending routine screening for depression in primary care.
The need for an efficient, reliable screening tool
Based on a recent review of the evidence on depression screening outcomes in primary care settings,10 the US Preventive Services Task Force (USPSTF) updated its screening recommendation in 2002 to include an endorsement of depression screening in adults “in clinical practices that have systems in place to assure accurate diagnosis, effective treatment, and follow-up” (strength of recommendation [SOR]=A).11 This endorsement leaves the primary care clinician with no guidance about how or when to screen for depression.
Despite lack of guidance in the USPTF guidelines, we believe depression screening can be done efficiently and reliably in primary care. However, one must begin by understanding that depression screening is different from screening for cancer or cardiovascular risk factors (Table 1). The burdens of interpretation of depression screening results are especially noteworthy. For example, the PRIME-MD Patient Health Questionnaire (PHQ) is reported to have a sensitivity of 61% and specificity of 94% for any mood or depressive disorder.12 This results in a positive predictive value (PPV) of 50% using a reasonable estimate of 10% prevalence for depression in primary care settings.13
Put simply, following administration and scoring of the PHQ, the clinician is left with little better odds than a coin toss of identifying a patient that has an active major depressive disorder requiring treatment. If there was no objective help, clinicians would have only their clinical judgment to resolve this, all during an office visit that contains many other competing agendas and demands.14,15
We have reviewed the evidence on depression screening instruments with the intent to highlight an instrument that clinicians can efficiently and reliably use to find depressed and impaired patients in their practice whom they might otherwise miss.
Burdens of screening for cancer, hyperlipidemia, and depression
|Burden of performance||Low||Simple test or performance of billable procedure||Low||Blood test||High||Time-intensive administration & scoring|
|Burden of interpretation||Low||Confirmatory testing often referred to specialists||Low||No confirmatory reference standard testing||High||High false positive rate w/burdensome reference standard|
|Burden of treatment||Low||Treatment done by specialists||High||Requires activation of patient & frequent monitoring||High||Requires activation of patient & frequent monitoring|
Two types of screening instruments
Depression screening instruments can be grouped into 2 categories:
- depression assessment scales, which ask patients to rate the severity or frequency of various symptoms
- symptom count instruments, which are based on depression criteria.
Depression assessment scales preceded symptom count instruments, and many were developed prior to the establishment of formal diagnostic criteria within the Diagnostic and Statistical Manual ofMental Disorders (DSM) system.16 Table 2 lists available examples of depression assessment scales and symptom count instruments, along with websites where you may access further information and the instruments themselves.
Accuracy and ease of administration of commonly available screening instruments
|Instrument||Time and scoring||LR+ (95% CI)||LR– (95% CI)||PPV (95% CI)||Web source|
|Beck Depression Inventory (BDI)32||2–5 min; simple||4.2 (1.2–13.6)||0.17 (0.1–0.3)||29.6% (10.7–57.6)||www.psychcorpcenter.com/content/bdi-II.htm|
|Center for Epidemiologic Studies Depression Scale (CES-D)34||2–5 min; simple||3.3 (2.5–4.4)||0.24 (0.2–0.3)||24.8% (20–30.6)||http://www.mhhe.com/hper/health/personal health/labs/Stress/activ2-2.html|
|Geriatric Depression Scale (GDS)35||2–5 min; simple>||3.3 (2.4–4.7)||0.16 (0.1–0.3)||24.8% (19.4–32)||http://www.stanford.edu/~yesavage/GDS.html|
|Hospital Anxiety and Depression Scale* (HADS)20||2–5 min; simple||7.0 (2.9–11.2)||0.3 (0.3–0.4)||41.3% (22.6–52.8)||www.clinical-supervision.com/hads.htm|
|Zung Self Assessment Depression Scale (Zung SDS)33||2–5 min; simple||3.3 (1.3–8.1)||0.35 (0.2–0.8)||24.8% (11.5–44.8)||http://fpinfo.medicine.uiowa.edu/calculat.htm|
|Primary Care Evaluation of Mental Disorders †(PRIME-MD)27||2 min; complex||2.7 (2.0–3.7)||0.14 (0.1–0.3)||21.3% (16.7–27)||Available upon request to Robert Spitzer, MD: RLS8@columbia.edu|
|PRIME-MD Patient Health Questionnaire (PHQ)||5–7 min; simple||10.2‡ (6.5–17.5)||0.4‡ (0.3–0.5)||50.4% (39.4–63.6)||fpinfo.medicine.uiowa.edu/calculat.htm|
|Symptom-Driven Diagnostic System for Primary Care†(SDDS-PC)||2 min; simple||3.5 (2.4–5.1)||0.2 (0.1–0.4)||25.9% (19.4–33.8)||No website available|
|PRIME-MD Patient Health Questionnaire (PHQ-9)||2 –5 min; simple||12.2 (8.4–18)||0.28 (0.2–0.5)||55% (45.7–64.3)||www.depression-primarycare.org/ap1.html|
|* Unless noted by (*), adapted from Williams et al.18|
|† Values reflect the initial brief screening portion of these instruments.|
|‡ PHQ vaues obtained from original position and reflect diagnosis of “any mood disorders.”|
|LR+, positive likelihood ratio; LR–, negative likelihood ratio; PPV, positive predictive value; CI, confidence interval|