Duke Anxiety-Depression Scale (DUKE-AD)

1. Abstract

The Duke Anxiety-Depression Scale (DUKE-AD) is a brief, psychometrically validated screening instrument engineered specifically for primary care and general clinical populations to identify co-occurring symptoms of anxiety and depressive disorders. Derived from the broader 17-item Duke Health Profile (DUKE) and the earlier 63-item Duke-UNC Health Profile (DUHP), the DUKE-AD addresses the high degree of psychiatric comorbidity observed between major depressive disorder, generalized anxiety disorder, and subthreshold mood-affective dysregulations in ambulatory medical settings. Comprising exactly seven self-administered items, the instrument utilizes a multidimensional response architecture: items 1 through 3 evaluate generalized self-perceptions, cognitive stamina, and social comfort using a 3-point rating scale (Yes, describes me exactly = 2; Somewhat describes me = 1; No, doesn’t describe me at all = 0), while items 4 through 7 evaluate somatic and affective functional impairments experienced during the preceding week (None = 0; Some = 1; A Lot = 2). Item 3 reflects a positively worded indicator of social ease and is reverse-scored. Raw summary scores are traditionally linearly transformed onto a normalized 0 to 100 metric, wherein elevated scores signify greater severity of affective distress and psychological dysfunction. Extensive validation studies demonstrate robust construct validity, high concordance with structured clinical diagnostic interviews (such as the DSM-based Diagnostic Interview Schedule), favorable sensitivity (ranging between 0.70 and 0.86), and strong specificity (ranging between 0.73 and 0.89) evaluated through receiver operating characteristic (ROC) curves. By offering an ultra-brief yet diagnostically sensitive screener, the DUKE-AD minimizes respondent burden while preserving critical diagnostic fidelity in fast-paced primary care consultations.

2. Keywords

Duke Anxiety-Depression Scale, DUKE-AD, Duke Health Profile, anxiety screening, depression screening, primary care psychiatry, psychometrics, affective disorders, psychiatric comorbidity, symptom severity assessment

3. Authors

The DUKE-AD was conceived, refined, and validated by a distinguished multidisciplinary research team led by George R. Parkerson, Jr., MD, MPH, alongside W. E. Broadhead, MD, PhD, and C. K. J. Tse, MPH, based at the Department of Community and Family Medicine at Duke University Medical Center in Durham, North Carolina, USA. Building on foundational research initiated in the late 1970s and early 1980s with collaborators including Stephen H. Gehlbach and Edward H. Wagner, the Duke primary care research group focused heavily on health-related quality of life (HRQoL), functional status, and the epidemiologic identification of unrecognized mental disorders in general medical practices.

Institutional Affiliation: Department of Community and Family Medicine, Duke University Medical Center, Durham, North Carolina, United States of America. Official repository and licensing inquiries are managed via the Duke Health Measures initiative.

4. Purpose

The primary clinical and epidemiological objective of the Duke Anxiety-Depression Scale is to bridge the widespread diagnostic gap in the detection of psychological morbidity within ambulatory medical settings. Epidemiological investigations consistently indicate that over 50% of patients meeting formal diagnostic criteria for major depressive disorder or generalized anxiety disorder present to primary care physicians rather than specialized psychiatric clinics. In these settings, psychological symptoms often masquerade as vague somatic complaints, chronic pain, fatigue, or autonomic hyperarousal, leading to substantial rates of underdiagnosis, inappropriate diagnostic testing, and delayed intervention.

Traditional psychiatric rating instruments—such as the Beck Depression Inventory (BDI), the Hamilton Rating Scale for Depression (HAM-D), or lengthy standardized diagnostic interviews—are generally impractical for routine primary care delivery due to their administrative length, complex scoring algorithms, or licensing constraints. Conversely, ultra-brief single-construct screeners often overlook the reality that clinical anxiety and depressive syndromes rarely occur in isolation. Comorbid anxiety and depression are associated with poorer treatment responses, elevated functional disability, prolonged illness chronicity, and an increased risk of suicidal ideation compared to either condition alone. The DUKE-AD was specifically designed to capture this unitary affective-distress spectrum using an economical, seven-item framework that can be completed by patients in under two minutes.

From an applied perspective, the DUKE-AD serves three primary roles:

• First-line screening: Efficiently identifying patients in general medical practices who require comprehensive psychiatric evaluation.
• Longitudinal monitoring: Measuring treatment trajectory, symptom attenuation, or relapse following pharmacological or psychotherapeutic interventions.
• Health services and epidemiological research: Providing a standardized, reliable index of affective dysfunction that facilitates cross-study comparisons across large population cohorts without placing an excessive response burden on participants.

5. Psychological Construct

The DUKE-AD operationalizes affective distress through a dimensional construct that conceptualizes anxiety and depression not as entirely discrete, mutually exclusive clinical entities, but as highly interrelated facets of negative emotionality, autonomic tension, and neurovegetative exhaustion. This perspective aligns closely with quantitative nosology and empirical psychopathology, recognizing common underlying features shared across emotional disorders.

The seven items within the DUKE-AD target distinct yet interconnected clinical indicators:

• Cognitive and Motivational Impairment (Items 1 and 2): Measured through items assessing task persistence (“I give up too easily”) and executive attentional control (“I have difficulty concentrating”). In depression and anxiety, cognitive slowing, impaired working memory, executive dysfunction, and feelings of learned helplessness represent core manifestations of affective dysregulation.
• Interpersonal / Social Functioning (Item 3): Captured via comfort in interpersonal environments (“I am comfortable being around people”). Social withdrawal, social anhedonia, and agoraphobic or social avoidance are frequent complications of both severe depressive states and heightened anxiety. Because this item reflects psychological resilience and social comfort, it is reverse-scored.
• Somatic and Neurovegetative Dysregulation (Items 4 and 5): Evaluated via reports of sleep disruption (“Sleeping”) and physical anergia (“Getting tired easily”). Sleep disturbances—including initial insomnia, frequent nocturnal awakenings, and non-restorative sleep—along with persistent daytime fatigue constitute shared somatic markers that frequently motivate primary care visits.
• Core Subjective Affective Distress (Items 6 and 7): Evaluated via direct mood-state self-reports of dysphoria (“Feeling depressed or sad”) and sympathetic nervous system hyperarousal or psychological apprehension (“Nervousness”). These two items capture the prototypical emotional signatures of depressive and anxious phenotypes, respectively.

Rather than forcing an artificial separation between somatic complaints and emotional symptoms, the DUKE-AD integrates physical, cognitive, social, and emotional domains into a single composite index of affective morbidity.

6. Theoretical Framework

The theoretical framework underpinning the DUKE-AD is grounded in Clark and Watson’s Tripartite Model of Anxiety and Depression, alongside the broader biopsychosocial framework of health proposed by George Engel. In the Tripartite Model, affective disorders are characterized by three structural components:

• General Distress / Negative Affectivity: A non-specific factor shared between anxiety and depression, comprising symptoms like emotional lability, irritability, insomnia, fatigue, and concentration difficulties.
• Physiological Hyperarousal: A component relatively specific to anxiety, manifested by symptoms like autonomic hyperactivity, motor tension, and subjective panic or nervousness.
• Anhedonia / Low Positive Affect: A component relatively specific to depression, characterized by a lack of energy, feelings of defeatism, social disengagement, and persistent sadness.

The DUKE-AD incorporates indicators across all three dimensions of this tripartite structure. Negative affectivity is represented through concentration difficulties, sleep disruptions, and subjective weariness. Physiological hyperarousal is captured through somatic nervousness and restless sleep. Anhedonia and loss of positive engagement are assessed via perceived helplessness (“giving up too easily”), social discomfort, and depressed mood.

Furthermore, the design of the DUKE-AD reflects George Parkerson and colleagues’ conceptualization of primary care functional health. In this framework, health is viewed as a multidimensional spectrum balancing physical, mental, and social functional capacities against specific symptom burdens. Parkerson argued that psychological suffering in primary care rarely fits neatly into rigid categorical diagnostic boundaries such as those in the DSM. Instead, subclinical presentations, mixed anxiety-depressive patterns, and somatic manifestations are standard. Consequently, an ecologically valid measurement tool must account for how emotional distress impairs general everyday performance, cognitive processing, and social interactions.

7. Validity

The psychometric validity of the DUKE-AD has been evaluated in multiple primary care cohorts, community epidemiological samples, and clinical trials.

Construct and Convergent Validity

Construct validity is evidenced by significant correlations between the DUKE-AD and established standardized instruments. In early validation studies conducted by Parkerson and Broadhead (1997), DUKE-AD scores demonstrated strong positive correlations with the General Health Questionnaire (GHQ), the Hopkins Symptom Checklist (SCL-90) anxiety and depression subscales (r values typically exceeding 0.65 to 0.78, p < 0.001), and the Mental Health Index of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36).

Criterion and Diagnostic Validity

Criterion-related validity was established against structured psychiatric diagnoses generated by the National Institute of Mental Health Diagnostic Interview Schedule (DIS). In clinical validation cohorts of adult primary care patients, Receiver Operating Characteristic (ROC) analyses demonstrated robust diagnostic discriminative capacity:

• Area Under the Curve (AUC): Reported ROC AUC values for identifying major depressive disorder and/or generalized anxiety disorder consistently range between 0.80 and 0.88, indicating strong screening precision.
• Optimal Cut-Off Performance: At established cut-off thresholds (typically scores ≥ 40 to 50 on the normalized 0–100 scale), sensitivity ranges between 70.0% and 86.4%, while specificity remains balanced between 73.2% and 89.1%, depending on the base-rate prevalence of affective illness in the sampled clinical setting.

Discriminant Validity

Discriminant validity is supported by lower correlations with purely physical functional measures (e.g., physical mobility subscales of the Duke Health Profile; r < 0.35) compared to mental and emotional health dimensions. This confirms that while physical ailments and functional limitations frequently co-occur with mental distress, the DUKE-AD specifically captures the affective-cognitive-neurovegetative cluster rather than general physical disability alone.

8. Reliability

The reliability of the DUKE-AD has been supported across diverse clinical populations, exhibiting solid internal consistency and temporal reproducibility despite its brief seven-item format.

Internal Consistency

Because Cronbach’s alpha is mathematically constrained by scale length, brief scales with seven or fewer items frequently yield modest coefficients. Nevertheless, the DUKE-AD regularly demonstrates Cronbach’s alpha coefficients ranging between 0.72 and 0.81 across adult ambulatory populations. These values satisfy established psychometric standards for group-level assessment and rapid screening instruments, reflecting acceptable inter-item correlation without excessive item redundancy.

Test-Retest Reliability

Temporal stability has been verified across various test-retest intervals. When re-administered over a 1-to-2 week interval among medically stable outpatients reporting no significant clinical changes, intraclass correlation coefficients (ICC) and Pearson correlation coefficients consistently range from 0.70 to 0.82. This degree of temporal stability indicates that the DUKE-AD reflects a stable symptom pattern over brief intervals while remaining sensitive to genuine clinical changes resulting from therapeutic interventions.

9. Factor Analysis

The latent structural integrity of the DUKE-AD has been examined through both exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), providing empirical insight into the dimensional nature of common affective disorders.

Exploratory Factor Analyses

Initial principal components analyses and unweighted least squares EFA with oblique rotations (promax/oblimin) typically extract either a dominant single-factor solution or a correlated two-factor solution:

• Unidimensional General Affective Distress Solution: Under a single-factor extraction, all seven items exhibit moderate-to-high factor loadings ranging between 0.48 and 0.82. The items with the highest loadings are typically Item 6 (“Feeling depressed or sad”) and Item 7 (“Nervousness”), confirming their roles as key indicators of the latent distress dimension.
• Bifactor / Correlated Two-Factor Model: In multi-factor extractions, the items tend to partition into: (1) Somatic-Cognitive Fatigue (Items 1, 2, 4, and 5) and (2) Emotional-Interpersonal Distress (Items 3, 6, and 7). These sub-dimensions demonstrate strong inter-factor correlations (r > 0.60), supporting the use of a combined, single composite scale score in clinical practice.

Confirmatory Factor Analyses

Confirmatory factor analytic investigations have assessed the structural fit of the unidimensional model against empirical observation. Standard goodness-of-fit indices typically confirm adequate to excellent model fit:

• Comparative Fit Index (CFI) > 0.94
• Tucker-Lewis Index (TLI) > 0.92
• Root Mean Square Error of Approximation (RMSEA) < 0.06 (90% CI: 0.041–0.078)
• Standardized Root Mean Square Residual (SRMR) < 0.05

Item loadings from CFA analyses consistently demonstrate that the individual items capture significant variance in the overarching affective distress construct (all standardized path coefficients λ > 0.45, p < 0.001).

10. Instrument / Measurement Tool

The DUKE-AD is a self-report paper-and-pencil or computerized questionnaire designed for fast clinical administration. Below is a structured summary of its technical characteristics and scoring rules:

• Instrument Type: Patient-Reported Outcome Measure (PROM) / Clinical Screening Questionnaire.
• Target Population: Adult primary care, outpatient, and general community populations (adaptable for adolescents aged 12 and above).
• Total Item Count: 7 items.
• Item Formats and Response Categories:
  • Items 1 to 3 (General Self-Perceptions):
    • 2 = Yes, describes me exactly
    • 1 = Somewhat describes me
    • 0 = No, doesn’t describe me at all
  • Items 4 to 7 (Past-Week Symptom Severity):
    • 0 = None
    • 1 = Some
    • 2 = A Lot
• Scoring and Transformation Rules:
  • Step 1 (Reverse Scoring): Item 3 (“I am comfortable being around people*”) is reverse-scored prior to aggregation: (0 becomes 2, 1 remains 1, 2 becomes 0).
  • Step 2 (Raw Summation): Calculate the raw score by summing all 7 items (Items 1, 2, recoded 3, 4, 5, 6, and 7). With 7 items each scored from 0 to 2, the total raw score ranges from 0 to 14.
  • Step 3 (Linear Normalization): Standardize the raw score onto a 0–100 scale using the following linear transformation formula:
    
    Standardized Score = (Raw Score / Maximum Possible Raw Score) × 100

Standardized Score = (Raw Score / 14) × 100
  • Step 4 (Interpretation): Higher scores indicate greater severity of anxiety-depression symptomatology and associated functional limitation. A transformed score of 0 denotes complete absence of reported distress, whereas a score of 100 reflects maximum symptom severity. In typical clinical screening protocols, a transformed cut-off score ≥ 40 to 50 indicates the need for formal clinical evaluation.

11. Permissions & Fee and Test Year

The DUKE-AD was derived from the Duke Health Profile and validated as an independent screening instrument by Dr. George R. Parkerson, Jr., and colleagues in the 1990s, with key validation benchmarks established in 1997 (Parkerson & Broadhead, Family Medicine). The instrument is copyrighted by Duke University Medical Center (Durham, North Carolina).

The instrument is made accessible for academic, clinical, and non-profit research applications under academic fair use or via modest administrative licensing arrangements managed through the Department of Community and Family Medicine at Duke University. Commercial entities, pharmaceutical clinical trials, or commercial digital health developers must obtain formal written licensing approval and pay applicable licensing fees prior to implementation. Detailed documentation, user manuals, and scoring scripts are available through the official Duke Health Measures service.

12. References

• McDowell, I. (2006). Measuring Health: A Guide to Rating Scales and Questionnaires (3rd ed.). Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195165678.001.0001
• Parkerson, G. R., Jr. (1994). User’s guide for the Duke Health Profile (DUKE). Department of Community and Family Medicine, Duke University Medical Center.
• Parkerson, G. R., Jr. (2002). User’s guide for Duke health measures. Department of Community and Family Medicine, Duke University Medical Center.
• Parkerson, G. R., Jr., & Broadhead, W. E. (1997). Screening for anxiety and depression in primary care with the Duke Anxiety-Depression Scale. Family Medicine, 29(3), 177–181. https://pubmed.ncbi.nlm.nih.gov/9085078/
• Parkerson, G. R., Jr., Broadhead, W. E., & Tse, C. K. J. (1990). The Duke Health Profile: A 17-item measure of health and dysfunction. Medical Care, 28(11), 1056–1072. https://doi.org/10.1097/00005650-199011000-00007
• Parkerson, G. R., Jr., Broadhead, W. E., & Tse, C. K. J. (1991). Comparison of the Duke Health Profile and the MOS Short-Form in healthy young adults. Medical Care, 29(7), 679–683. https://doi.org/10.1097/00005650-199107000-00008
• Parkerson, G. R., Jr., Broadhead, W. E., & Tse, C. K. J. (1991). Development of the 17-item Duke Health Profile. Family Practice, 8(4), 396–401. https://doi.org/10.1093/fampra/8.4.396
• Parkerson, G. R., Jr., Broadhead, W. E., & Tse, C. K. J. (1992). Quality of life and functional health of primary care patients. Journal of Clinical Epidemiology, 45(11), 1303–1313. https://doi.org/10.1016/0895-4356(92)90171-t
• Parkerson, G. R., Jr., Broadhead, W. E., & Tse, C. K. J. (1995). Health status and severity of illness as predictors of outcomes in primary care. Medical Care, 33(1), 53–66. https://doi.org/10.1097/00005650-199501000-00005
• Parkerson, G. R., Jr., Broadhead, W. E., & Tse, C. K. J. (1996). Anxiety and depressive symptom identification using the Duke Health Profile. Journal of Clinical Epidemiology, 49(1), 85–93. https://doi.org/10.1016/0895-4356(95)00508-0
• Parkerson, G. R., Jr., Gehlbach, S. H., Wagner, E. H., et al. (1981). The Duke-UNC Health Profile: An adult health status instrument for primary care. Medical Care, 19(8), 806–828. https://doi.org/10.1097/00005650-198108000-00002

13. Items of the Scale