Screening for depression in adults

INTRODUCTION — Depression is the most common psychiatric disorder in the general population [1] and the most common mental health condition in patients seen in primary care [2-5]. Undiagnosed, depression is associated with decreased quality of life as well as risks for mortality and other adverse health outcomes. Thus, systematic screening carries the potential for substantial benefit.

This topic will review the rationale for screening for depression, including the evidence for its benefits, harms, and cost-effectiveness. It will also address who to screen, screening instruments, and implementation of screening into primary care practices.

The epidemiology, risk factors, clinical presentation, diagnosis, and management of unipolar major depression are discussed elsewhere:

●(See "Unipolar depression in adults: Epidemiology".)

●(See "Unipolar depression in adults: Clinical features".)

●(See "Unipolar depression in adults: Assessment and diagnosis".)

●(See "Major depressive disorder in adults: Approach to initial management".)

DEFINITIONS

●Major depressive disorder – This topic focuses on screening for major depressive disorder, or major depression. Major depressive disorder consists of at least one episode of major depression and no history of mania or hypomania. An episode of major depression is a period lasting at least two weeks that manifests with depressed mood and/or loss of interest or pleasure and causes significant distress or functional impairment. Other common symptoms include sleep difficulties, changes in appetite, decreased concentration, feelings of worthlessness, fatigue, and recurrent thoughts of death. Diagnostic criteria for major depression appear in a table (table 1) [6].

●Other depressive disorders – Screening for depression may also detect persistent depressive disorder (dysthymia), minor depression, prolonged grief disorder, or bipolar disorder.

•Persistent depressive disorder (dysthymia) is characterized by depressed mood and at least two other depressive symptoms that last for at least two years. (See "Unipolar depression in adults: Clinical features".)

•Minor depression is defined by fewer (one to four) depressive symptoms and tends to have shorter, less severe episodes. (See "Unipolar minor depression in adults: Epidemiology, clinical presentation, and diagnosis".)

•Prolonged grief disorder is a form of grief that is unusually protracted, intense, and disabling. It is characterized by maladaptive thoughts and behaviors and dysregulated emotions. (See "Prolonged grief disorder in adults: Epidemiology, clinical features, assessment, and diagnosis".)

•Bipolar disorder is a mood disorder characterized by episodes of major depression and either mania (bipolar I disorder) or hypomania (bipolar II disorder).

●Relevant terminology – Trials of screening interventions for depression often use the following terms to measure clinical outcomes [7]:

•Response – Response is the reduction of depression symptoms by a specified amount. Response is usually defined as an improvement in symptom score of ≥50 percent that is still above the threshold for remission. Partial response is usually defined as an improvement in symptom score of 25 to 50 percent.

•Remission – Remission is the reduction of symptoms below the threshold required to meet a diagnosis of major depression that is maintained for at least one month.

•Recovery – Recovery is the reduction of symptoms below the threshold required to meet a diagnosis of major depression that is maintained for at least six months.

•Relapse – Relapse is the return of depression symptoms prior to the time of recovery.

•Recurrence – Onset of a new episode of major depression after recovery has occurred.

WHO TO SCREEN

Routine for all patients — We recommend screening all adult patients for depression. Screening all patients maximizes the likelihood of detecting individuals with depression and minimizes potential bias in selecting individuals for screening and intervention.

Decisions about screening hinge on whether the net benefits of screening and treatment outweigh the potential harms [8]. Benefits of depression screening include improved rates of detection, the opportunity for earlier intervention with effective treatment, and improved depression outcomes. (See 'Benefits and harms of screening' below.)

Depression is highly prevalent throughout the world, with a reported lifetime prevalence in adults that ranges from 3 to 17 percent [9]. In the United States, the National Epidemiologic Survey on Alcohol and Related Conditions III identified an annual and lifetime prevalence of major depression of 10 and 21 percent, respectively [10].

Untreated depression is associated with decreased quality of life [11], increased risk of suicide [12], and increased risk of and poor outcomes from chronic medical conditions (eg, diabetes, cardiovascular disease) [13,14]. (See "Unipolar depression in adults: Course of illness", section on 'Mortality' and "Unipolar depression in adults: Clinical features", section on 'Comorbidity'.)

The most robust support for routine screening derives from studies that embed screening within a comprehensive depression program that includes practice innovations for engaging, treating, and monitoring individuals identified by screening. Ideally, such practice supports should be in place to optimize the benefits of screening. (See 'Practice support' below.)

The US Preventive Services Task Force (USPSTF) recommends screening for depression in the general adult population, including pregnant and postpartum individuals [15]. The Department of Veterans Affairs recommends that all patients not currently receiving treatment for depression be screened using the Patient Health Questionnaire-2 (PHQ-2) [16].

Alternative approach: Targeted screening — Targeted screening is an alternative approach that assesses only subsets of individuals.

●Screening based on clinical symptoms – One target group might be those whose symptoms trigger a suspicion of depression. The likelihood of a depressive disorder increases by 1.5 to 3.5 times if a patient reports any of the following symptoms [17]:

•Insomnia

•Fatigue

•Chronic pain

•Recent life changes or stressors

•Fair or poor self-rated health

•Unexplained physical symptoms

●Screening based on risk factors – Clinicians who utilize targeted screening should have a heightened index of suspicion for depression in individuals with risk factors. Risk factors for depression involve genetic, medical, environmental, and social influences and include female sex, older age, history of childhood trauma, low socioeconomic status, alcohol or substance use disorder, chronic medical conditions, personal or family history of depression, and recent stressful events, including childbirth [10,18]. These are discussed in detail separately. (See "Unipolar depression in adults: Epidemiology", section on 'Demographic risk factors' and "Unipolar depression: Pathogenesis", section on 'Pathogenesis'.)

As an example, depressive disorders are highly prevalent in patients with chronic medical conditions and can have a negative impact on outcomes for those diseases. Although screening may be difficult to prioritize for these patients, it is particularly important. The prevalence of depression is approximately 25 percent in patients with chronic health problems [19]. Depression is especially common in patients with diseases of the central nervous system (eg, stroke, traumatic brain injury, Parkinson disease) [20-22], cardiovascular disorders [23-25], cancer [26], and conditions involving immune and inflammatory mechanisms (eg, systemic lupus erythematosus [27]). Depressive disorders can have a negative impact on outcomes for those diseases. (See "Unipolar depression in adults: Clinical features", section on 'Other medical illnesses'.)

Compared with screening all adults, targeted screening decreases false positives and might be more efficient, especially in populations with a low prevalence of depression [28,29]. However, this approach is likely to miss more individuals who have a depressive disorder and may introduce bias into the detection of those with depression. (See 'Decreased health disparities' below.)

Guidelines from Canada and the United Kingdom recommend a more targeted approach. (See "Society guideline links: Screening for depression".)

●Guidelines from the United Kingdom's National Institute for Health and Clinical Excellence (NICE) suggest being alert to possible depression, particularly if there is a depression history or chronic physical health problem with functional impairment, and screening patients in whom a suspicion of depression exists [30].

●Guidelines from the Canadian Task Force on Preventive Health Care (CTFPHC) recommend not routinely screening for depression in adults with no history of depression and no apparent symptoms of depression, including not screening those who may be at increased risk of depression [31,32]. They advise that clinicians remain alert to symptoms of depression (eg, insomnia, low mood, anhedonia, and suicidal thoughts), especially in individuals with characteristics that increase depression risk.

BENEFITS AND HARMS OF SCREENING — Several key factors inform decisions about screening. These include characteristics of available screening tests (ie, are they accurate, acceptable, feasible, safe, and cost-effective), the disease (ie, is it common and/or deadly), and its treatment (ie, does early treatment improve outcomes) [33,34] and, most importantly, whether the net benefits of screening and treatment outweigh potential harms [8]. These components are summarized below and described more generally separately. (See "Evidence-based approach to prevention".)

Improved detection

●Underdetection is common – Depression in primary care commonly remains undetected. In the absence of screening, only an estimated 50 percent of patients with major depression are identified [35], and only 35 percent receive care within a year of symptom onset [36]. Unless they are directly asked, few individuals discuss their symptoms with their primary care clinicians. Moreover, two-thirds of primary care patients with depression present with somatic symptoms (eg, headache, back problems, or chronic pain), making detection more difficult if a screening tool is not used [37,38].

Patients omit information about depressive symptoms for a variety of reasons. These include fear of stigmatization, concerns about confidentiality, beliefs that depression isn't a "real" illness or falls outside the purview of primary care, and beliefs that they should be able to get better "on their own." They may also wish to avoid being prescribed antidepressant medication or referred to a therapist [39].

●Screening can improve recognition – Screening interventions improve the detection of depression in primary care settings. A 2023 review for the US Preventive Services Task Force (USPSTF) found that screening in adults increases the rate of depression diagnosis (absolute increase 10 to 47 percent), even without other practice enhancements to improve depression care [40,41]. A subsequent meta-analysis of 7576 patients found that clinicians were 27 percent more likely to recognize depression in settings that incorporated depression screening or case-finding instruments into practice [42].

Early treatment — The benefits of treating individuals with depression are well documented. Moreover, chronic depression is associated with poorer treatment response [43], which underscores the importance of early intervention.

A 2023 review for the USPSTF summarized the results of 39 systematic reviews of psychological and pharmacologic treatments for depression [44]:

●Pooled results of 59 studies of psychological interventions in primary care patients documented a moderate effect of any treatment (standardized mean difference [SMD] -0.42, 95% CI -0.56 to -0.29).

●The meta-analysis of studies of antidepressant medication treatment demonstrated increased rates of response to treatment and remission. As an example, treatment with fluoxetine demonstrated an increased odds of treatment response (odds ratio [OR] 1.52, 95% CI 1.40-1.66) and remission (OR 1.46, 95% CI 1.34-1.60) with a small reduction on symptom severity (SMD -0.23, 95% CI, -0.28 to -0.19).

The efficacy of specific depression treatments is reviewed separately. (See "Major depressive disorder in adults: Approach to initial management" and "Major depressive disorder in adults: Initial treatment with antidepressants".)

Improved depression outcomes — Screening interventions for depression modestly improve depression outcomes, including lowering the prevalence of clinically important depression symptoms and increasing rates of depression response and remission [15].

These data are summarized in a systematic review for the USPSTF [44]. Seventeen trials (18,437 participants) examined the impact of depression screening interventions on clinical outcomes and included studies on patients in general medicine practices, older patients, and pregnant and postpartum patients. Results were as follows:

●Screening was associated with a lower prevalence of clinically significant depression symptoms at six months (median absolute risk decrease 5.2 percent; OR 0.6, 95% CI 0.50-0.73; I² = 0%).

●Screening was associated with higher rates of remission at six months (median absolute risk increase 7.2 percent; OR 1.58, 95% CI 1.23-2.02; I² = 0%).

Several caveats affect the broad applicability of these data to existing primary care practices.

●Most interventions occurred in the context of programs that offered enhanced depression care management. Although the independent contribution of screening in these complex interventions is difficult to determine, depression screening clearly improves outcomes when coupled with appropriate follow-up and treatment. (See 'Practice support' below.)

●Although screening coupled with high-quality care improves depression remission rates, screening alone does not clearly translate into higher rates of antidepressant prescribing (relative risk [RR] 1.20, CI 0.87-1.66) or intervention more generally (RR 1.30, CI 0.97 to 1.76) [42].

Decreased health disparities — Routine screening may ameliorate disparities in depression care. In the United States, inequities exist across the spectrum of depression care, including screening. As an example, compared with White adults, non-Hispanic Black and Asian American individuals may be less likely to receive screening or assessment for depression [45]. Additionally, Black and Hispanic/Latino persons are more likely to be misdiagnosed and less likely to receive mental health services compared with White or Asian American persons [44]. In primary care settings, they are also less likely to receive counseling, referrals for therapy, and antidepressant medication [45,46].

Routine screening of all patients may help to minimize these disparities. A large cohort study that implemented routine depression screening in six primary care practices (n = 52,944 adults) documented both increases in rates of depression screening (baseline 41 percent to postintervention 89 percent) and reductions in differential rates of screening based on patient age, language preference, race/ethnicity, and insurance type [47].

Limited research has evaluated the effectiveness of depression screening in traditionally underserved patient groups, including Black, Hispanic/Latino, Native American, and Asian American adults; immigrants; non-English-speaking patients; and gender-diverse individuals [44]. The USPSTF has encouraged more studies on the effectiveness of screening tools and interventions for these individuals as well as investigation of the potential role of implicit bias in adversely affecting screening rates [15,44].

Cost effectiveness — Limited evidence supports the cost-effectiveness of interventions to screen for depression in general medical settings, especially when coupled with enhanced models of depression care. Depression imposes a significant economic burden, accounting for billions of dollars annually in the United States [48]. The financial impacts of depression include those on the individual patient, families' finances [49], health care expenditures for family members [50,51], and labor costs due to low work productivity [52].

Cost-utility analyses from two trials of depression interventions in primary care found costs of screening per quality-adjusted life year (QALY) that ranged from USD $9478 to $36,467. This range falls below the generally accepted cost-utility threshold in the United States (≤$50,000 per QALY) and is comparable to the cost-utility of screening for hypertension, cholesterol, and breast cancer [53-56]. By contrast, a study using a Markov model found that the cost-utility of depression screening fell below a potentially acceptable threshold only when performed every five years (1999 USD $85,697 per QALY) but not annually ($192,444 per QALY) [57].

Cost-effectiveness and cost-utility thresholds are discussed elsewhere. (See "A short primer on cost-effectiveness analysis", section on 'Cost-effectiveness ratio'.)

Harms of screening and treatment

●Acceptability of screening – Depression screening is highly accepted, with few patients finding the process burdensome or upsetting [58-60].

●Possible harms associated with detection – Limited evidence suggests that depression screening is not associated with significant harm, although this has been understudied [45,61]. Potential harms of depression screening include overdiagnosis and resultant stigma, labeling effects, and unnecessary treatment. Potential harms of screening are discussed more generally elsewhere. (See "Evidence-based approach to prevention", section on 'Unintended consequences of screening'.)

●Harms of treatment – Although screening could conceivably lead to harms from depression treatment, the risk of serious adverse effects from antidepressant medications and psychotherapy is low. Systematic reviews of psychological treatment or online interventions for depression have not identified significant harms or worsening of depression symptoms [45].

Potential risks of antidepressant medications include suicide and other more common but less severe side effects. Suicide is the most severe potential adverse effect of antidepressants; however, the absolute risk is very low. As an example, a review of US Food and Drug Administration (FDA) regulatory data found a very low increased risk of suicide attempts from second-generation antidepressants (ie, selective serotonin reuptake inhibitors [SSRIs], serotonin–norepinephrine reuptake inhibitor [SNRIs]), with 0.7 percent of antidepressant users attempting suicide compared with 0.3 percent of nonusers [62]. Because events are rare, it is not clear if antidepressants increase the risk of death from suicide [15] (see "Major depressive disorder in adults: Approach to initial management", section on 'Safety of antidepressants'). The absolute risk of other serious side effects from antidepressant medications is low [41].

Antidepressants commonly cause other side effects that are not serious but can significantly impact patients' ability to tolerate the medications. In clinical trials, dropout rates due to adverse effects are higher among participants randomized to antidepressant treatment [44]. Side effects vary depending on the class of antidepressant and appear in a table (table 2).

●Opportunity costs of screening – Screening for depression could also take time from the encounter that clinicians and patients might use to discuss other issues (ie, "opportunity cost").

SCREENING TESTS

Evaluating a screening test — Several screening instruments have been developed and validated for use in primary care and other settings. When choosing a screening test, clinicians should consider the following factors [63,64]:

●Ease of administration (patient- versus clinician-completed, number of questions, required reading level)

●Ease of scoring and interpretation

●Validation in diverse populations (eg, different clinical settings, groups of patients, multiple languages)

●Use of an appropriate reference standard (eg, "gold standard" against which the test is compared)

●Test accuracy in the population being screened (usually measured by sensitivity, specificity, and/or likelihood ratios)

Screening tests generally involve a tradeoff between sensitivity (proportion of true positive results) and specificity (proportion of true negative results). A test with high sensitivity will have a low proportion of false-negative results, which is desirable for a screening test; however, it will often also have a low specificity (ie, high proportion of false-positive results). Standard cutoffs for the depression screening instruments described below optimize the balance between sensitivity and specificity. A general approach to evaluating tests is summarized elsewhere. (See "Evaluating diagnostic tests".)

Test characteristics of common screening instruments for depression are summarized in a table (table 3). The accuracy of screening instruments for depression is validated against structured diagnostic interviews, such as the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Questionnaires that range from 2 to 10 questions perform well [44,63,65].

Two-step approach to screening — We suggest a two-step approach to depression screening (algorithm 1).

●Step 1 – Start with a brief screen using the two-question screen or the Patient Health Questionnaire-2 (PHQ-2)

●Step 2 – Individuals with a positive screen should undergo additional screening with the Patient Health Questionnaire-9 (PHQ-9)

Two-question screen — To start screening, we recommend the two-question screen because of its ease of use and test characteristics (ie, sensitivity and specificity). The two-question screen uses the first two questions from the PHQ-9 (table 4). A "yes" answer to either question constitutes a "positive" result.

●During the past two weeks, have you often been bothered by feeling down, depressed, or hopeless?

●During the past two weeks, have you often been bothered by having little interest or pleasure in doing things?

This instrument has been evaluated in 10 studies of over 4618 participants and has a reasonable tradeoff between high sensitivity (95 percent) and moderate specificity (65 percent) [44]. The accuracy of this instrument for screening older adults is discussed below. (See 'Older patients (ages 65 and older)' below.)

Given its low specificity, a positive screen should prompt further assessment, ideally with an instrument that has a lower rate of false-positive results (ie, higher specificity), such as the PHQ-9 or Geriatric Depression Scale-15 (GDS-15).

Patient Health Questionnaire-2 — The PHQ-2 is an alternative to the two-question screen. The PHQ-2 is a brief, self-administered instrument that contains the same questions as the two-question screen but is scored differently. Compared with the two-question screen, the PHQ-2 may be more difficult to complete and score because it uses a 4-point Likert scale (0 to 3) rather than a dichotomous yes/no response. A score of 2 or more is considered a "positive" result.

The PHQ-2 has been widely validated and demonstrates relatively high sensitivity and reasonable specificity:

●Test sensitivity is comparable to the two-question screen. A meta-analysis of 48 studies (n = 11,703) found that at a cutoff of 2 or more, the PHQ-2 had a sensitivity and specificity of 91 and 67 percent, respectively, when compared with a semistructured interview [44].

●The PHQ-2 may be slightly less sensitive in older individuals than the general population. (See 'Older patients (ages 65 and older)' below.)

Individuals who screen positive with the PHQ-2 should undergo additional screening with the PHQ-9.

Patient Health Questionnaire-9 — Individuals who screen positive with either the two-question screen or the PHQ-2 should undergo additional screening with the PHQ-9. The PHQ-9 is a nine-item instrument whose questions map directly to DSM-5 criteria for major depression (table 5). We recommend the PHQ-9 because it has been widely validated across diverse patient populations and in multiple languages and has acceptable sensitivity and specificity.

●Interpretation – The PHQ-9 asks respondents to rank their symptoms on a 0 to 3 Likert scale. Scores range from 0 to 27 with a higher score indicating more severe symptoms. A score of 10 or more indicates a possible depressive disorder. The PHQ-9 includes a question about suicide and also assesses whether depressive symptoms are impairing function, a key criterion to establish a DSM-based diagnosis [6].

Positive test results, including an affirmative response to the question about suicide, require follow-up assessment. (See 'Evaluating a positive result' below.)

●Sensitivity and specificity – In an individual patient data meta-analysis of 47 studies (n = 11,234), the sensitivity and specificity of the PHQ-9 compared with a semistructured interview were 0.85 and 0.85, respectively.

The PHQ-9 demonstrates higher specificity than the PHQ-2 or two-question screen and so will decrease the likelihood of a false-positive result. As an example, using a prevalence of 10 percent for major depressive disorder or dysthymia, a score of less than 10 on the PHQ-9 yields a negative predictive value of 99 percent.

●Validation in diverse populations – The PHQ-9 has been validated in diverse patient populations and is easily accessible in many languages.

●Monitoring symptom severity and treatment response – Clinicians can also use the PHQ-9 to assess the severity of a patient's depression symptoms and monitor the response to treatment over time. (See "Using scales to monitor symptoms and treat depression (measurement based care)" and "Unipolar depression in adults: Assessment and diagnosis".)

This two-step approach affords the ease of a short screening instrument for all patients and reduces the risk of false-positive results by following positive screens with the PHQ-9.

●A 2023 meta-analysis of 10,627 participants that used this two-step strategy with an initial PHQ-2 (cutoff score of ≥2), followed by a PHQ-9 for those who screened positive (cutoff score of ≥10), demonstrated a sensitivity and specificity that was comparable to PHQ-9 screening alone (sensitivity of 0.82 and specificity of 0.87) [44].

●In a meta-analysis of over 44,000 participants, the combined administration of the PHQ-2 (cutoff score of ≥2) followed by a PHQ-9 for those who screened positive reduced the number of participants needing to do the full PHQ-9 by 57 percent [66]. The sensitivity and specificity of this two-step strategy was similar to screening all individuals with a PHQ-9.

The PHQ-9 is not sufficiently accurate to establish a definitive diagnosis of depression [67]. As an example, using a prevalence of 10 percent for major depression, a PHQ-9 score of 10 or higher yields a positive predictive value of only 45 percent for a diagnosis of major depression. Scores exceeding the threshold for a positive screen should prompt a careful diagnostic assessment. (See 'Evaluating a positive result' below.)

Other instruments — Several additional instruments have been evaluated for depression screening and include:

Geriatric Depression Scale-15 for older patients — The GDS-15 is an alternative tool for screening older adults (ages 65 and older), especially those with comorbid illnesses that may make results of the PHQ-9 more difficult to interpret. Although either the GDS-15 or PHQ-9 can be used for medically stable older adults, it is more feasible in most primary care settings to use a single approach for all patients, such as the two-step approach (see 'Two-step approach to screening' above). The GDS-15 may be preferrable in practices that focus on older adults.

In a meta-analysis of depression screening instruments in older adults, the GDS-15 and PHQ-9 demonstrated comparable pooled sensitivities and specificities although the PHQ-9 was slightly more specific [68].

●The GDS-15 uses a yes/no response format, which is easier to answer than the Likert scales used by the PHQs.

●To address possible biases introduced by symptoms of medical illness or the process of normal aging, the GDS-15 does not include questions about somatic symptoms. Instead, it includes questions such as:

•Are you basically satisfied with your life?

•Do you often get bored?

•Do you feel that your life is empty?

•Do you often feel helpless?

The GDS-15 is a self-report instrument that has been studied in multiple settings and demonstrates good test accuracy across the spectrum of older populations.

●A meta-analysis of seven studies of the GDS-15 reported an optimal balance between sensitivity and specificity with a cutoff of ≥5. Pooled sensitivity and specificity at this cutoff were 0.94 and 0.81, respectively [45].

●Other versions of the GDS exist (ie, GDS-5, GDS-30), but they have not been as extensively validated [45].

Beck Depression Inventory for Primary Care — The Beck Depression Inventory for Primary Care (BDI-PC) is a seven-item scale [69] adapted from the extensively validated 21-item Beck Depression Inventory (BDI-II) [70,71]. The 21-item BDI-II is useful for monitoring treatment response.

In primary care outpatients, the BDI-PC with a cutoff of four points had 97 percent sensitivity and 99 percent specificity for identifying major depression [72]. However, the BDI is available only by license and thus has limited utility for screening.

Center for Epidemiologic Studies Depression Scale — The Center for Epidemiologic Studies Depression Scale (CES-D) is a 20-item self-report measure that assesses depression as experienced during the past week [73]. It uses a Likert format (0 to 3 scale) with overall scores that range from 0 to 60.

The CES-D is widely available and has been validated across different age, gender, and cultural populations [74]. In a meta-analysis of 28 studies (10,617 participants), the CES-D had a pooled sensitivity of 0.87 and specificity 0.70 at a cutoff of 16 [75].

World Health Organization (Five) Well-Being Index — The World Health Organization (Five) Well-Being Index (WHO-5) (form 1) has excellent sensitivity but is less specific than other instruments [76].

PRACTICAL IMPLEMENTATION, FOLLOW-UP, AND PRACTICE SUPPORT

When and how to screen — To facilitate ease of implementation, we support screening during a routine health visit.

The two-question screen, Patient Health Questionnaires 2 and 9 (PHQ-2 and PHQ-9), and Geriatric Depression Scale (GDS) are all designed to be self-administered by patients. In practices with an electronic health record (EHR), patients can complete screening questions electronically before the visit. Alternatively, staff can verbally administer or distribute questionnaires in the examination room before the patient sees the clinician.

Use of previsit videos or interactive computer programs to engage patients in recognizing depression symptoms could potentially augment screening uptake. In one randomized trial, patients with depressive symptoms who used a tailored, interactive computer program prior to their visit were more likely to be treated for depression (by antidepressant prescription and/or referral) than control patients but did not experience improved mental health outcomes at 12 weeks [77].

Frequency of screening — The optimal frequency of screening is not established by evidence [15]. Although screening every five years may be more cost-effective than yearly screening [57], annual screening or screening at the time of a health maintenance examination may be easier to incorporate into routine practice.

Clinicians may choose to screen certain patients at particularly high risk of depression more frequently, including individuals who have multiple chronic illnesses, are postpartum, or have anxiety or substance use disorders.

Evaluating a positive result — Because depression screening will generate some false-positive results, all patients with a positive screening test (eg, PHQ-9 ≥10) require a thorough diagnostic evaluation to confirm a diagnosis of major depressive disorder. Trials show that screening is associated with improved clinical outcomes when it is coupled with careful diagnostic assessment and treatment [41,78-80].

A confirmed diagnosis should prompt clinicians to assess symptom severity and evaluate for comorbid diagnoses that may complicate treatment (eg, anxiety disorders, alcohol or substance use disorders, posttraumatic stress disorder). In patients with bipolar disorder, symptoms of major depression are more common than and often present prior to symptoms of mania or hypomania; hence, evaluation of a positive depression screen should include an assessment for symptoms of mania or a history of bipolar disorder. (See "Bipolar disorder in adults: Assessment and diagnosis".)

Regardless of whether they meet criteria for major depression, all individuals who endorse suicidal thoughts or ideation require further evaluation and, potentially, expedited referral to a mental health professional and/or transfer to the emergency department. (See "Suicidal ideation and behavior in adults", section on 'Patient evaluation'.)

The diagnosis of depression is discussed in detail separately. (See "Unipolar depression in adults: Assessment and diagnosis".)

Practice support — Because the most robust evidence for depression screening derives from studies that embed screening within comprehensive depression care programs, depression screening should ideally occur with adequate systems in place to ensure diagnosis, treatment, and appropriate follow-up [15]. Innovations to engage, monitor, and treat individuals identified by screening will optimize benefits of screening. Many successful screening interventions for depression have included staff support for coordination and monitoring of care [41]. Common features of such interventions include facilitating referrals, engaging patients in depression self-management, and monitoring depression treatment, including dose adjustment of and adherence to antidepressant medications [79].

Multicomponent depression care interventions may be impractical for some primary care practices. Nonetheless, practices can work to integrate behavioral health care into routine workflows and processes of care [81]. Staff might provide support with symptom monitoring, self-management plans, medication adherence, patient education, assessment of patient preferences and goals, and/or referrals.

Medicare and many other health insurers reimburse practices for integrated behavioral health services [82], facilitating the financial viability of offering such services [83]. Examples of system supports for depression care include [80,84,85]:

●A nurse who screens patients for depression, informs the clinician of a positive screen, and facilitates referral for evidence-based behavioral treatment

●Trained care managers who assess patient symptoms at baseline and follow-up, using a standardized instrument, and who assess treatment adherence

●Collaborative care involving direct coordination between mental health specialists and primary care

●Depression care that includes active self-management support and follow-up for a minimum of 16 weeks

SPECIAL POPULATIONS — We also recommend routine screening for the following individuals.

Older patients (ages 65 and older) — We recommend routine screening for adults ages 65 and older. Although older individuals, especially those with medical comorbidities, are at risk of depression, screening and assessment for depression in these patients present special challenges. Older patients may be more reluctant to acknowledge depression due to the perceived stigma of mental illness or beliefs that depression symptoms are the result of "normal aging" or will not improve with treatment [86]. Moreover, clinicians may struggle to differentiate symptoms of depression from those of concurrent medical illnesses or medication side effects. Cognitive impairment of patients may also make screening more difficult [87].

We suggest a similar depression screening strategy in older adults as for the general population (see 'Two-step approach to screening' above). The two-question screen and the Patient Health Questionnaires 2 and 9 (PHQ-2 and PHQ-9) have been validated and show comparable performance in older compared with younger populations. As an example, a diagnostic meta-analysis of 132 studies (46,506 participants) evaluated depression screening instruments in older adults (mean ages 60 to 89) and found the following [68]:

●In six studies, the two-question screen demonstrated good sensitivity and adequate specificity for diagnosing major depression (pooled sensitivity 90 percent and pooled specificity 66 percent).

●In seven cohorts, the PHQ-2 demonstrated a pooled sensitivity and specificity of 97 and 77 percent, respectively, for identifying major depression. These cohorts used a cut-off threshold of 3 or higher, which would be expected to decrease sensitivity and increase specificity compared with the standard cutoff of 2.

●In 14 studies, the pooled sensitivity and specificity of the PHQ-9 were 83 and 86 percent, respectively, for the outcome of depression.

Alternatively, clinicians may consider using screening instruments that are specifically developed for older adults. These include the Cornell Scale for Depression in Dementia, which can be used to evaluate individuals with cognitive impairment [88], and the Geriatric Depression Scale. (See 'Geriatric Depression Scale-15 for older patients' above.)

Evidence supporting the impact of depression screening on clinical outcomes is less robust for older individuals. A US Preventive Services Task Force (USPSTF) meta-analysis found that depression screening of older patients demonstrated smaller improvements in symptoms and remission rates compared with outcomes for the general population. Only one study utilized a screening instrument designed specifically for older adults [15].

Individuals who are pregnant or postpartum — Peripartum depression is common and often underrecognized. The two-question screen and PHQ-9 have been studied in pregnant and postpartum individuals and demonstrate reasonable sensitivity and specificity in these individuals [45].

Specialized depression questionnaires are also available for these populations. Screening of pregnant and postpartum persons is discussed elsewhere.

●Pregnant individuals (see "Unipolar major depression during pregnancy: Epidemiology, clinical features, assessment, and diagnosis", section on 'Screening')

●Postpartum individuals (see "Postpartum unipolar major depression: Epidemiology, clinical features, assessment, and diagnosis", section on 'Screening' and "Bipolar disorder in postpartum women: Epidemiology, clinical features, assessment, and diagnosis", section on 'Screening')

●Partners who have recently become parents (see "Postpartum paternal depression", section on 'Screening')

Adolescents (ages 12 to 21) — Depression screening in adolescents is discussed separately. (See "Screening tests in children and adolescents", section on 'Depression and suicide risk screening'.)

Individuals with cancer — All individuals with a new cancer diagnosis should receive depression screening using the two-step approach (see 'Two-step approach to screening' above). Patients with cancer are at higher risk of developing depression. Additionally, detecting depression poses challenges in these patients because the symptoms of cancer and its treatment can overlap those of depression (eg, fatigue, sleep disturbance, anorexia). Depression screening in patients with cancer is discussed elsewhere. (See "Patients with cancer: Clinical features, assessment, and diagnosis of unipolar depressive disorders", section on 'Screening'.)

SUMMARY AND RECOMMENDATIONS

●Routine screening for all patients – We suggest routine screening of all adults for depression (Grade 2B). Without screening, depression is often undetected, particularly since most patients do not disclose depression symptoms unless directly asked, and at least two-thirds of patients with depression in primary care settings present with predominantly somatic symptoms. (See 'Routine for all patients' above and 'Improved detection' above.)

Compared with screening all adults, targeted screening based on risk factors decreases false positives; however, it may miss more cases of depression and exacerbate health inequities. (See 'Alternative approach: Targeted screening' above.)

●How to screen

•Two-step approach – We use a two-step approach to depression screening (algorithm 1). We start with a two-question screen (table 4) or the Patient Health Questionnaire-2 (PHQ-2) (table 6).

Those with a positive screen should then complete the Patient Health Questionnaire-9 (PHQ-9) (table 5) or a similar instrument (table 3). (See 'Two-step approach to screening' above.)

•Timing and frequency of screening – The optimal frequency of screening is uncertain.

To facilitate ease of implementation, we support screening at the time of each preventive health visit. (See 'When and how to screen' above and 'Frequency of screening' above.)

●Evaluation of a positive screening test – All patients with a positive screening test for depression (eg, PHQ-9 ≥10) require a thorough diagnostic evaluation to confirm a diagnosis of major depressive disorder and evaluate the appropriateness of treatment. They should also be assessed for suicidal ideation, mania, and level of functional impairment. Individuals with suicidal thoughts or ideation require urgent safety evaluation and follow-up. (See 'Evaluating a positive result' above.)

●Rationale for screening

•Burden of disease – Depression is highly prevalent worldwide and is a leading cause of disability and decreased quality of life. Major depressive disorder is associated with increased rates of all-cause mortality and worse outcomes for several chronic medical illnesses (eg, coronary heart disease, diabetes). In primary care settings, major depressive disorder is underdiagnosed and undertreated.

•Benefits of screening – Screening can improve the detection and diagnosis of depression as well as clinical outcomes, especially when screening is part of an enhanced approach to depression care. Screening for depression can lead to a decrease in depression symptoms and increased rates of remission at six months. Earlier detection may also contribute to improved treatment outcomes. Depression screening is likely cost-effective and may reduce disparities in depression care, especially if routine screening of all patients is implemented. (See 'Benefits and harms of screening' above.)

•Harms of screening – Depression screening has few harms. These primarily relate to adverse effects of pharmacotherapy (table 2), including a very small increased risk of suicide attempts. (See 'Harms of screening and treatment' above.)

●Special populations – We use a similar approach for screening individuals who are older (>65), individuals who are pregnant or postpartum, adolescents, or individuals who have cancer. Alternative instruments have been developed and validated for screening in these populations. These and specific issues pertaining to such patients are discussed elsewhere. (See 'Special populations' above and "Unipolar major depression during pregnancy: Epidemiology, clinical features, assessment, and diagnosis", section on 'Screening' and "Postpartum unipolar major depression: Epidemiology, clinical features, assessment, and diagnosis", section on 'Screening' and "Postpartum paternal depression", section on 'Screening' and "Screening tests in children and adolescents", section on 'Depression and suicide risk screening' and "Patients with cancer: Clinical features, assessment, and diagnosis of unipolar depressive disorders", section on 'Screening'.)