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DEPRESSION IN PRIMARY CARE
PART 1: SCREENING AND DIAGNOSIS

Patient Health Questionnaire
Patient Health Questionnaire 9 (PHQ-9) is useful in screening for depression. It is a self report questionnaire and consists of nine items looking at depressives symptoms over the previous two weeks plus one question concerning functional impairment²⁰. A shorter version is known as Patient Health Questionnaire 2 (PHQ-2) which consists of two items with ‘yes’ or ‘no’ response.  It can be used as a screening tool for depression and intended for use with PHQ-9 if PHQ-2 is ‘positive’ (‘yes’ to either question). ²¹ The Malay version is also available and validated but the sensitivity and specificity of the tool is quite low. The possible explanation is the different understanding and cultural variation of depression between the study sample and Western population.²³

Hamilton Depression Rating Scale
The Hamilton Depression Rating Scale (HDRS) is a clinician-administered scale to assess the severity of depressive symptoms. The original version has 17 items²⁴ and a later version has 21 items which include the subtype of depression. The limitation of this scale is that it does not assess the atypical symptoms of depression e.g. hypersomnia or hyperphagia. Other versions include HDRS-29, HDRS-8, HDRS-6, HDRS-24 and HDRS-7.22

Geriatric Depression Scale
Geriatric Depression Scale (GDS) is a simple self report scale to assess depression in the elderly.²⁵ The original version has 30 items with ‘yes’ or ‘no’ response. Other shorter versions are GDS 15, GDS 10 and GDS 4.22 The Malay version (M-GDS-14) is translated from GDS 15. However, it only has 14 items as item-9 from the Malay version was omitted as it does not have discriminatory value in differentiating cases from non-cases.²⁶

If the same rating scale is administered repeatedly to the same patient, it can be used to assess that patient’s progress.

Co-morbidity
Depression is often seen in patients with chronic medical problems, e.g. chronic pain, sleep disorders, diabetes, stroke, malignancies, endocrine problems particularly thyroid disorders and other psychological disorders such as anxiety,¹⁷ eating disorders, dementia and schizophrenia.  More than 75 per cent of patients diagnosed with depression in a primary care setting also suffer from anxiety disorder¹⁷ which could be one of the following:

1. Patient fulfils the criteria for major depressive disorder but suffers subsyndromal levels of anxiety symptoms.
2. Patient fulfils the criteria for anxiety disorder but suffers subsyndromal levels of depressive symptoms.
3. Patient fulfils the criteria for both, i.e. anxiety and depressive disorders.
4. Patient presents with both symptoms but these symptoms are not severe enough to fulfil the criteria.

Apart from that, co-morbidity with substance abuse is also common. Treatment for the underlying medical disorders can contribute to the development of depression as well. Some of the medications that may cause or worsen depression²⁷ include beta-blockers, interferons, phenytoin, calcium channel blockers, corticosteroids, indomethacin, histamine-2 blockers, narcotics, cytotoxic drugs, etc. Screening for underlying medical problems is important for late onset depression especially in the absence of family history²⁷. Depression can precipitate and exacerbate chronic illness, and vice versa.²⁸ Presence of a psychosocial stressor for depression in a medical patient should never mitigate treatment; as Stewart JT quoted in his paper “this is similar to withholding morphine for severe chest pain once a myocardial infarction was diagnosed”.¹⁴ Generally, depressive disorders assume an important role in the aetiology, course and outcome associated with chronic disease.²⁹

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