keith s. dobson, ph.d
TRANSCRIPT
Screening- the systematic application of a tool to identify individuals with sufficient risk of disorder to warrant further action. Note that risk can be identified different ways, including risk indicators or early signs/ symptoms.
Case- finding- the systematic application of a tool to identify individuals with a suspected disorder, and to differentiate these persons from others without that disorder. Note that case finding can be applied generally to a population, or within high-risk groups.
Screening can be applied to identify individuals high on a risk indicator, and so often employs severity measures. Severity measures can be used to establish levels of risk for a given disorder.
Case- finding usually involves a diagnostic tool, or the development of cut-offs, to differentiate cases from non-cases, with respect to the diagnosis of interest.
There are at least 35 general scales of depression:
Note: Some scales have short forms
Severity Scales◦ Children’s Depression Inventory (CDI)◦ Depression and Anxiety in Youth Scale (DAYS)◦ Kutcher Adolescent Depression Scale (KADS)◦ Reynolds Adolescent Depression Scale (RADS)◦ Reynolds Child Depression Scale (RCDS)◦ Youth Depression Adjective Checklist (Y-DACL)
Diagnostic Scales◦ Kiddie- Schedule for Affective Disorders and
Schizophrenia (K-SADS)◦ Structured Clinical Interview for DSM (SCID)
Often, the strategy is to employ a screening tool as a first step, followed by a case-finding “gold standard”, such as diagnosis
This strategy works well to evaluate specificity and sensitivity
It is predicated on the existence of a “gold standard”, however, and a condition which can be definitively determined, which may not be true in Major Depression
Depression Severity- As assessed on screening tool
Cut-point
Depression Severity- As assessed on screening tool
False FalseNegatives Positives
Cut-point
Depression Severity- As assessed on screening tool
False FalseNegatives Positives
Not DepressedNot Depressed
DepressedDepressed
Cut-point
A goal is to maximize both sensitivity and specificity; in theory the ideal instrument has a ratio of 1.0 (perfect prediction) in both dimensions.
Tools can be compared on these dimensions, using a Receiver Operating Characteristics curve
By adjusting the cut-offvalue, the optimal cut-off, to maximize the area under thecurve, can be found
CES-D 20
CES-D 10
Note: These are all studies with adults.From Whooley, et al (1997).
The psychometric properties of the screening tool
The psychometric properties of the “gold standard”
The base rate, or prevalence, of the condition that is being screened for
The population (e.g. community versus at risk versus clinic)
Comorbid conditions that conflate the screening tool and gold standard (e.g. medical or mental disorders, poverty, abuse)
Screening in childhood and adolescence has been reviewed by the US Preventive Services Task Force (2010).
They identified 9 “fair-quality” studies of MDD screening-instrument accuracy in children and adolescents with 6 depression instruments.
Only one study included children younger than 10 years of age, and the results were poor.
Based on these results, the Task Force made no recommendation for screening of depression in children aged 6 to 11.
Of the studies with adolescents, 2 were conducted in primary care settings, 1 in a community setting, and 5in school settings.
Based on these study results, the Task Force reported that only two instruments demonstrated good sensitivity and specificity in primary care settings in adolescents.
The PHQ-Adolescent (PHQ-A) had a sensitivity of 73% and a specificity of 94%, where as the BDI-Primary Care (BDI-PC) had a sensitivity of 91% and a specificity of 91% .
Their recommendation:
“We found no data describing health outcomes among screened and unscreened populations.
Although the literature on diagnostic screening test accuracy is small and methodologically limited, …very limited available data suggest that primary care–feasible screening tools have been reasonably accurate in identifying depressed adolescents.
Studies are needed to assess whether these findings can be replicated by other research groups in larger studies that include patients from a variety of primary care settings.”
Source: (Williams, et al, 2009)
Open source set of materials for screening, assessment diagnosis, and treatment
Based on “best evidence” Uses a group of experts on mental health
issues and paediatrics.
Identification Recommendation I: Patients with depression risk
factors (such as history of previous episodes, family history, other psychiatric disorders, substance abuse, trauma, psychosocial adversity, etc.) should be identified (Grade of Evidence: C. Strength of Recommendation: Very Strong) and systematically monitored over time for the development of a depressive disorder. (Grade of Evidence: C. Strength of Recommendation: Very Strong).
Assessment/DiagnosisRecommendation I: PC clinicians should evaluate
for depression in high-risk adolescents as well as those who present with emotional problems as the chief complaint. (Grade of Evidence: B. Strength of Recommendation: Very Strong)
Clinicians should assess for depressive symptoms based on diagnostic criteria established in the DSM IV or ICD 10 (Grade of Evidence: B. Strength of Recommendation: Very Strong) and should use standardized depression tools to aid in the assessment. (Grade of Evidence: A. Strength of Recommendation: Very Strong).
Assessment/Diagnosis
Recommendation II: Assessment for depression should include direct interviews with the patients and families/caregivers (Grade of Evidence: B. Strength of Recommendation: Very Strong) and should include the assessment of functional impairment in different domains (Grade of Evidence: B. Strength of Recommendation: Very Strong) and other existing psychiatric conditions. (Grade of Evidence: B. Strength of Recommendation: Very Strong)
Screening in adolescence should be predicated on risk factors, significant impairment in social, school or family functioning, and/ or distress.
Screening in adolescence requires a second stage, to confirm a case of Major Depression, and to warrant intervention.
Significant predictors Nonsignificant predictorsLow parental support RacePoor family functioning AgePoor school functioning Parental educationLow peer support Negative attributional styleDelinquency PerfectionismBulimic symptoms Poor peer functioningBody dissatisfaction Substance useDepressive symptomsEmotionalityLow physical activityLow peer support
Sample was 496 adolescent girls, assessed over 4 years. From Seeley, Stice & Rohde (2009)
Time and burden for respondent Scoring time and effort Cost (e.g. proprietary tools) Reading level of tool Source of information (child, parent, other) Co-morbid conditions
Do not apply screening to children younger than 12 years of age. Study tools and value of screening, with a preliminary focus in primary care.
Screen for depression in adolescents (aged 12- 18), but only in those who present with risk indicators, functional impairment and/ or distress.
Tools to consider include:◦ The PHQ- Adolescent◦ The BDI- Primary Care◦ The Kutcher Adolescent Depression Scale (KADS)-
11 or 6 item version (requires further research)
Screening should always be a first step in case-finding
Further research on screening for depression is clearly warranted, in both children and adolescents
Research should focus on:◦ Sensitivity and specificity of various tools◦ Interaction among variables such as age, gender, and/or
risk factors, and screening outcomes◦ Sources of screening information◦ Screening settings (e.g. community versus clinic)◦ Incremental value of screening for treatment◦ Costs of screening◦ Effects of screening on system requirements (e.g.
diagnosis; treatment; service provision; training)
