By the year 2020, depression is projected to reach second place in the ranking of Disability Adjusted Life Years (DALYs) calculated for all ages.
Major depressive disorder is associated with a high degree of personal disability, multiple morbidity, suicide and lost quality of life for patients, families and carers. Patients with chronic depression may also be high service users with significant economic implications.
This article deals only with screening for depression in primary care. See the separate articles on Depression, Depression in Children and Adolescents and Postnatal Depression for details of epidemiology, investigations and management.
Requirements of screening
For a system of screening to be viable it must fulfil certain criteria:
- The condition must be sufficiently common to merit screening. This does not necessarily mean common in the whole population unless there is universal screening. It means common in the target group for screening.
- There must be an effective intervention for the condition that is being sought.
- Screening must result in the condition being recognised at an earlier stage when intervention is more effective.
- There must be high specificity (low rate of false positives) and a very high sensitivity (very low rate of false negatives), although this is difficult to assess when evaluating a screening tool for depression.
- The screening test must be relatively cheap or else the cost per case detected is prohibitively expensive.
- It must be safe, easy to use and acceptable to the patient.
Who should be screened?
In one sense the General Medical Services (GMS) contract has simplified the situation in identifying patients with coronary heart disease and diabetes as being prioritised for screening. However, practices still undertaking the National Enhanced Service are obliged to recognise depression at an early stage in any patient. This represents a considerable workload and it may be best to focus one's attentions on patients deemed to be 'at risk'.
National Institute for Health and Care Excellence (NICE) guidelines suggest screening in those with a past history of depression, significant physical illness - especially if it causes disability - and other mental health problems like dementia. Other situations where the chance of depression is very high include:
- Parkinson's disease where the disease is common but often missed.
- Dementia where the two diseases can easily resemble each other.
- The puerperium - screening may show positive results in as many as 13%.
- Alcoholism and drug abuse - it may be difficult to decide if depression is the cause or effect of substance abuse but it may be desirable to treat both.
- Victims of abuse.
- Physical disease like cancer, cardiovascular disease or diabetes.
- Chronic pain.
- Stressful home environments.
- The elderly.
- Social isolation.
- Unexplained symptoms.
Depression may be more difficult to detect in patients with physical illness because both conditions can have similar symptoms.
Screening and assessment tools
A number of screening and assessment tools have been validated and are generally available.
Initial screening in patients who may have depression
NICE recommends that any patient who may have depression (especially those with a past history of depression or who suffer from a chronic physical illness associated with functional impairment) should be asked the following two questions:
- During the last month have you been feeling down, depressed or hopeless?
- During the last month have you often been bothered by having little interest or pleasure in doing things?
If a patient with a chronic physical illness answers 'yes' to either question, the following three questions should be asked:
During the last month, have you often been bothered by:
- Feelings of worthlessness?
- Poor concentration?
- Thoughts of death?
Assessing newly diagnosed patients
These tools include:
- Patient Health Questionnaire (PHQ-9): this is a nine-item questionnaire which helps both to diagnose depression and to assess severity. It is based directly on the diagnostic criteria for major depressive disorder in the Diagnostic and Statistical Manual - Fourth Edition (DSM-IV). It takes about three minutes to complete. Scores are categorised as minimal (1-4), mild (5-9) , moderate (10-14), moderately severe (15-19) and severe depression (20-27). It can be downloaded free from the internet.
- Hospital Anxiety and Depression (HAD) Scale: despite its name, this has been validated for use in primary care. It is designed to assess both anxiety and depression. It takes about five minutes to complete. The anxiety and depression scales each have seven questions, and scores are categorised as normal (0-7), mild (8-10), moderate (11-14) and severe (15-21).
- Beck Depression Inventory® - Second Edition (BDI-II): this also uses DSM criteria. it takes about five minutes to complete. It is an assessment of the severity of depression and is graded as minimal (0-13), mild (14-19), moderate (20-28) and severe (29-36). It consists of 21 items to assess the intensity of depression in clinical and normal patients. Each item is a list of four statements arranged in increasing severity about a particular symptom of depression. It is also not free but can be purchased from the supplier's website.
Other screening tests may be useful in particular situations. They include:
- Interview-based tools (such as Kiddie-Sads and Child and Adolescent Psychiatric Assessment) can be used for children and young adults suspected of having depressive illness.
- The Center for Epidemiologic Studies Depression (CES-D )Scale and Reynolds' Adolescent Depression Scale (RADS) are more suitable for adolescents.
- The Edinburgh Postnatal Depression Scale (EPDS) - a self-rating scale - is for puerperal depression.
- The Geriatric Depression Scale (GDS) is suitable for older patients.
- The Cornell Scale for Depression in Dementia (CSDD) is suitable for patients with dementia.
Although screening tools are useful, they should not be a substitute for clinical judgement. The patient's history, family history and the existence of comorbidities should be taken into account when diagnosing or assessing depression
Further reading and references
; NICE Public Health Intervention Guidance (October 2008)
; Screening for child and adolescent depression in primary care settings: a systematic evidence review for the US Preventive Services Task Force. Pediatrics. 2009 Apr123(4):e716-35.
; Depression: the disorder and the burden. Indian J Psychol Med. 2010 Jan32(1):1-2. doi: 10.4103/0253-7176.70510.
; NICE, 2011
; Depression in primary care: current and future challenges. Can J Psychiatry. 2013 Aug58(8):442-8.
; NICE Clinical Guideline (October 2009)
; UK Screening Portal
; When should women be screened for postnatal depression? Expert Rev Neurother. 2010 Feb10(2):151-4.
; Screening to identify patients at risk: profiles of psychological risk factors for early intervention. Clin J Pain. 2005 Jan-Feb21(1):38-43
; NICE Clinical Guideline (April 2016)
; GL Assessments
; Harcourt Assessment
; NICE (September 2005)
; University of California, San Francisco
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