# 01 - 1. General principles

# 1. General principles

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1. General principles 
Rating scales give clinicians an objective benchmark to support critical treatment decisions. 
Regular use of rating scales can provide information that aids in diagnosis, prognosis and 
therapeutic monitoring. Further, when self-report scales are used, an item-by-item analysis can 
help to identify the exact symptoms that a patient considers most troublesome and challenging so 
they can be targeted during the consultation process. 
Rating scales can be used for (1) screening for the presence of a psychiatric condition (2) 
diagnosis of a psychiatric illness (such scales are often termed diagnostic schedules) (3) 
estimating severity of various conditions and their response to treatment (4) assess functional 
capacity and well-being. 
Rating scales can be either self-rated or observer rated. Some observer-rated scales require clinical 
experience (clinician-rated) while trained non-clinical personnel can use others. 
Self-rated 
Observer rated 
Beck’s Depression Inventory 
Zung Depression Inventory 
Symptoms checklist SCL 
GHQ 
Lunser’s (extrapyramidal) 
Edinburgh postnatal depression scale 
Dementia scales 
PANSS 
BPRS 
HAMD 
MADRS 
YBOCS 
SCID 
Scales are based on psychometric properties; aim to measure dimensions of psychopathology 
(symptoms) often at the present state (the duration of which is defined variously). Schedules are 
based on clinical expectations; deal with categories of disorders (syndromes) based on known 
classification systems. A schedule may be devised to focus on either past or present status or both. 
Two types of procedures are used when selecting items (symptoms) for scales. The first method 
is based on the previous clinical literature to determine the appropriate items. The second 
method is based on calibration. In this method, a large number of questions are tested to find the 
most discriminating items between a ‘known ill’ and a ‘presumed well’ group. The items that are 
most significant in a statistical sense are chosen to represent the scale that is devised. 
Considerations for selecting a screening measure for use in a study include 
 Characteristics of the population to be screened, 
 Psychometric properties of the instrument, 
 Time required to complete the measure, 
 Ease of use, and 
 Cost of obtaining the measure

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General Health Questionnaire is an all-purpose screening tool that is often used as a first-level 
assessment instrument in epidemiological studies before detailed diagnostic schedules are 
employed. 
 Goldberg introduced the General Health Questionnaire (GHQ) 
 GHQ was developed as a screening tool to detect those likely to have or be at risk of 
developing psychiatric disorders 
 It is available in a variety of versions using 12, 28, 30 or 60 items, the 28-item version is used 
most widely. 
 Each item is scored as a 4 point Likert (0-3) allowing a total possible score on the GHQ 28 of 0 
to 84. 
 Using alternative binary scoring method (with least symptomatic items scoring 0 and the 
most symptomatic items scoring 1), the 28- and 30-item versions classify any score exceeding 
the threshold value of 4 as achieving ‘psychiatric caseness’. The caseness threshold is 3 for 
the 12-item version. Psychiatric caseness is a probabilistic term—whereby, if such 
respondents presented in general practice, they would be likely to receive further attention. 
 It should be noted that the GHQ is not usually used for predictive purposes. 
 Reliability coefficients have ranged from 0.78 to 0.95 in various studies.