J.H.K.C. Psych. (1991) 1, 31-36

REVIEW ARTICLE

TTHE JUDICIAL USE OF RATING INSTRUMENTS IN THE CLINICAL ASSESSMENT OF GERIATRIC DEPRESSION
Bernard W.K. Lau

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Summary

Many rating scales for depression are popular in use but few of them are suitable for use in Chinese elderly populations in view of the general emphasis on physical symptoms in the scales and the tendency of Chinese to somatise their psychological discomfort. Geriatric Depression Scale, which is currently available, may mitigate the psychometric disadvantages and be utilised to screen Chinese elderly communities for prevalence of depressive illness, on account of its ease, simplicity, validity and reliability.

INTRODUCTION

DEPRESSION IN OLD AGE

Depressive illnesses, as epidemiological studies have consistently shown, are among the most frequent mental disorders encountered in hospital or everyday practice. In modern society, the rapidly changing psychosocial environment of man often gives rise to situations of acute and/or prologed environmental stress, which may then bring about depressive reactions. At a time when more and more individuals are suffering from the unsettling effects of uprooting, family disintegration, and social isolation, for instance, it is hardly surprising that the prevalence of psychiatric disorders, which will often be of a depressive nature, will be certain to spiral upwards.

The current rise in morbidity from chronic diseases is also likely to contribute to the number of those with depression. Cardiovascular diseases, collagen diseases such as rheumatism, gastroenterological diseases, and cerebravascular and other neurological diseases have been shown to be associated with depressive illness in as many as 20 per cent of all cases.

In this context, it is, therefore, common sense that with increasing age and infirmity individuals must be more vulnerable to depression, and in fact it is now widely recognised that depression is the most common psychiatric problem from which an aging individual is liable to suffer (Verwoerdt, 1981; Thompson, 1984; Cami, Davison & Webster, 1984; Martin & Gambrill, 1986).

Nevertheless, these depressed elderly are generally unwilling to seek treatment for ·mental disorders and are particularly reluctant to initiate contact with mental health professionals (Butler, 1969; Gaitz, 1974; Waxman, Carner & Klein, 1984). On the other hand, evidence indicates that physicians often fail to recognise, diagnose and treat, or refer their elderly patients who are depressed (Waxman & Carner, 1984), although their clinical manifestations are not radically different from those observed in younger people. In spite of this, there remain a number of characteristics or problems which are specific to old-age depression. Cognitive symptoms, for instance, though observed in adult depressive states, may become so prominent in the elderly that they induce a "pseudodementia" (Kiloh, 1961).

Another problem in the assessment of geriatric depression is that elderly individuals are typically more resistant to psychiatric evaluation than younger patients (Salzman & Shader, 1978; Wells, 1979). Somatic symptoms, that are usually a key to the diagnosis of depression in the young individuals, lose their specificity as they become 'normal' or common accompaniments of aging. For instance, sleep disturbances, decline of sexual function, constipation, aches and pains are common symptoms of endogenous depression, but are also common in nondepressed elderly individuals (e.g., Coleman et al, 1981). Questions appropriate for use with the young patient may not be appropriate for the old. For example, questions about sexuality often make the elderly defensive, and yet they are included on many existing psychiatric rating scales, Other questions may pose problems of patient acceptance and may also lead to problems of interpretation (Blumenthal, 1975). For example, questions about suicidal intent, whether life is worth living or whether one is hopeful about the future, may measure very different things in persons near the beginning and those reaching the end of the life span.

CLINICAL ASSESSMENT

The assessment of depression depends on information which is derived for the most part from two different sources: on the one hand, verbal communication, coming principally from the patient himself or from his family, either spontaneously or prompted by questions from the doctors, and, on the other, observations made by the clinician, especially in relation to peculiarities of behaviour such as psychomotor abnormalities.

Normally the key to diagnosis of depressive disorder in patients with multiple somatic complaints is a careful history screening for the vegetative components of depression. In most cases, the best method of detecting symptoms of depression is to put a number of specific questions to the patient in the course of the consultation. Although it is essential to listen to the patient attentively and patiently, these key questions make it possilbe to recognise depression in about 80 per cent of cases. To a certain extent the exploratory examination also has a psychotherapeutic aspect since it is, as it were, the first step on the way to a good doctor-patient relationship.

The depression level can be further determined by both clinical interview and rating scales. Of course, global judgment, because it is based on traditional clinical practice, has always been regarded as more fundamental than scales and therefore has been the criterion for their validation.

USES OF RATING SCALES

Standardised instruments for the quantitative and objective evaluation of psychopathology have proliferated first as a consequence of the need to objectify characteristics of psychiatric disorders in clinical trials of psychotropic drugs. Interests in nosological and pathogenetic problems and in epidemiology of psychiatric conditions have further prompted the development of psychopathometric scales, In this connection, one of the advantages of rating scales is that they provide an assessment expressed in numerical terms that is suitable for automatic processing. Nowadays, these rating scales are well known to most psychiatrists and are generally considered to be useful in attaining a standardised assessment of depressive symptomatology, especially in the research field. There are two types of scales in popular use. The Observer's Rating Scales are concerned with all the information, whatever its nature, normally gathered by the observer, whereas the Self-Report Inventories register the subject's verbal responses to questions put to him in regard to his symptoms at the moment of the examination.

Theoretically speaking, a good scale should incorporate items relevant to the condition being investigated; it should be able to keep to a minimum any confusion between symptoms of the illness and side-effects of treatment; it should be able to quantify differences rather than be based on the presence or absence of individual items; its results should not be influenced by knowledge of tl:ie patient's past history; it should have inter-rater reliability so that different investigators may obtain similar results; and it should be relatively easy to administer. For depressive states, a rating scale's content validity should be evaluated by the combination symptom score: cognitive (negative beliefs, guilt); motor (verbal inertia, reduced gesture); social (introversion, work); mood of depression (sadness, hopelessness); and mood of anxiety (worrying, panic).

In clinical practice a rating scale can tell us how ill a patient is. In clinical research it can allow us to match groups of patients according to severity. It can also quantify, as a clinical measure, the effects of treatment (Carroll et al, 1973). It can even go a long way towards standardising communication between clinicians (Beck et al, 1961) locally and also internationally (Bech et al, 1975).

According to Boyd and Weissman (1982) such rating scales are attractive in that they are economical and inexpensive. For example, a major advantage of self-report scales lies in their reduced cost in terms of research effort, time and professional expertise which are required. Most self-report scales are brief and tend to be cost-efficient. While some supervision is required in their completion, this can be done without involving the psychiatrists or clinical psychologists. Interview assessments take longer and usually require professionals as raters and special additional training for reliability. Moreover, the scores recorded on rating scales would successfully quantify the severity of a psychopathological syndrome. It thus lends itself nicely to actuarial methods. With the extremely rapid development of the personal computer industry, such tests are easily administered and scored by computer.

Furthermore, viewed only from the perspective of gathering and evaluation of verbal information given by the subject in regard to his current state, Self-Report Inventories may be superior to the inquiry carried out by a doctor during a clinical examination provided that the instruments used are properly constructed and applied.

ARGUMENTS AGAINST RATING SCALES

In general, rating scales have been criticised for two aspects: the excessive subdivision of the clinical picture they are believed to impose and the incompleteness of the symptomatological pattern they are supposed to cover. In fact, these scales do not clearly reveal the clinical significance of depressive symptoms, i.e., whether they are prodromal of a depressive syndrome, and what therapeutic intervention they may warrant (Boyd & Weissman, 1982). In addition, it has been thought that rating scales fail to reflect the specific features of individual patient. It has also been feared that the specialist would be made to conform to a preconceived scheme, and that the use of rating scales would disrupt the doctor-patient relationship, since the patient will be treated as an object.

There is no doubt that a certain clash necessarily exists between the results obtained by the Self-Report Inventories and the diagnosis based on a clinical examination. This happens for two reasons. The first is that, while the Inventories furnish information only on subjective symptomatology, other elements, verbal or otherwise, are also used in reaching a clinical diagnosis. The second is that the SelfReport Inventories are only concerned with the patient's current state, while the clinical diagnosis includes a temporal dimension. A Self-Report inventory is a purely empirically constructed scale giving only a transectional view without including any information about the course of the illness, whereas the diagnosis of depression takes into account the duration of the symptoms. Besides, the experienced clinician has greater flexibility to elaborate and modify his questions according to the particular situation and even to verify from other sources of information the accuracy of the patient's responses. Nevertheless it can be shown that the detection level of a rating scale approaches that obtained in a clinical examination provided that the appropriate technique is used. The following are the more frequently employed psychiatric rating scales for investigation of depression.

class="jnlHead">HAMILTON RATING SCALE FORDEPRESSION

One of the earliest developed and best known of the interview-based rating scales for depression is the Hamilton Rating Scale for Depression (Hamilton, 1960; 1967). The Scale was devised as a means of recording objectively the signs and symptoms of depression. It is intended for the evaluation of patients already diagnosed as depressed.

This 17-itern inventory was designed to be completed by an experienced observer after a 30-minute clinical interview assaying symptoms of "endogeneous" depression (Lyerly, 1978). It includes a range of both psychological symptoms (e.g., depressed mood, guilt, suicidal ideation, difficulties at work, and loss of interest in hobbies and social activities) and physical symptoms (e.g., insomnia, somatic symptoms, hypochondriasis).

It is rated for severity (on a scale of O to 4 for some items and O to 2 for others) by the clinician,based on interview and other data available, In its usual form, the patient's score is the sum of all the ratings, capable of distinguishing between different degrees of depression (Carroll et al., 1973; Knesevich et al, 1977; Biggs, et al, 1978). It correlates well with clinical judgment (Bech, 1981). Although it was intended to be a measure of treatment outcome rather than a screening device, it may also be useful as a diagnostic aid (Schnurr, Hoaken & Jarrett, 1976). The Scale has been reported to be sensitive to the effects of different treatments for depression, such as electroconvulsive therapy (e.g. Robin & Harris, 1962) and tricyclic antidepressant pharmacotherapy (e.g. Waldron & Bates, 1965). It has become popular for drug trials, both as a basis and as a standard for other scales (Hamilton, 1967). It is simple to use and is readily taught to or rapidly learned by raters (Hamilton, 1967).

However, many of the items are concerned with somatic symptoms, on the assumption that they are frequent sources of disability and patients usually complain about them. The structure of the Scale .makes it score highly when somatic symptomatology is present, but underestimate the severity of depression in patients with few somatic symptoms or concerns. Its other major disadvantage is that it is difficult to use frequently on the same subject, as it is intended to record the patient's condition over the last week or two. Such items as disturbed sleep, libido and weight cannot meaningfully be assessed daily.

Furthermore, the Scale has not been validated for use in elderly population (Yesavage et al., 1983), although Sarteschi et al. (1973) have found the Scale able to discriminate between depressed and anxious patients over the age of 60.

BECK DEPRESSION INVENTORY

The Beck Depression Inventory (Beck et al., 1961) is probably the most widely used self-report inventory which measures the behavioural and subjective manifestations of depression. The purpose is to discriminate intensity of depression, and not to differentiate diagnostic categories.

This Inventory was constructed to provide a quantitative assessment of the intensity of depression as evaluated by the patient. Although it was initially designed to be administered by trained interviewers, the Inventory is most often used as a self-administered scale. It need not be administered by an observer with psychiatric training (Bech, 1981). This Inventory was derived from clinical observations about the attitudes and symptoms displayed by depressed psychiatric patients. The observations were systematically reduced to 21 symptoms and attitudes which could be rated from O to 3 in terms of intensity. As with most of such scales, the patient has to judge how he feels at the time and pick the statement that most closely matches his current experience. Most important of all, the items were chosen to assess the intensity of depression and were not selected to reflect any developmental theory of depression. Items categorised include mood, pessimism, crying spells, guilt, self-hate and accusations, irritability, social withdrawal, work inhibition, sleep and appetite disturbance, and loss of libido. The content of the Inventory emphasises pessimism, a sense of failure, and self-punitive wishes.

The Inventory is sensitive to changes associated with psychopharmacological trials, varying psychotherapeutic techniques, and a variety of medical problems and thus is a useful tool for assessing treatment progress. In practice, the Inventory correlates well with other tests of depression and does discriminate between anxiety and depression. However, Hamilton (1969) points out that the Beck inventory is limited to the patient's evaluation of himself at the time of the interview and cannot take into account fluctuations in the patient's condition. Retardation, agitation, and loss of insight are not covered, and anxiety is represented only by "irritability". The rating procedure is also open to observer bias and is not self-rating in the usual sense.

This Inventory has been demonstrated to be reliable when used with the elderly (Gallagher, Nies & Thompson, 1982), and use of traditional cut-off scores for diagnostic classification has good agreement with diagnoses established using the SADS/RDC approach (Gallagher et al 1983). Zemore and Eames (1979) found that the levels of depression were comparable in the two elderly groups, but somatic symptoms were more prevalent in the elderly group than in the younger group. Elderly persons may not be more depressed than younger groups if the somatic symptoms concurrent with the aging process are discounted.

One should remain cautious in applying the Inventory to older individuals with acute or chronic medical disorders, as 7 of the 21 items refer to symptoms such as fatigue, sleep difficulty, appetite disturbance, weight loss, sexual disinterest, and worry about health.

ZUNG SELF-RATING DEPRESSION SCALE

Among the single-dimension self-report instrument, the Zung scale (1965) is one of the most commonly employed. The Scale was designed to measure the subjective intensity of depression regardless of whether it occurs as an illness in itself or as a symptom of another illness, emotional or physical. Thus it is not intended for use in diagnosis.

The Scale consists of 20 statements, each of which the respondent must rate on a 4-point scale, as the item pertains to him or herself. The items were based on those clinical diagnostic criteria most commonly used to characterise depressive disorders. To prevent the patient from establishing a bias in his answers, half the statements are worded positively, and the other half negatively.

The Zung scale had the advantage of being short, brief and easy to read and understand. The statements are couched in terms that the patient can be expected to understand. The scores have been reported as showing good correlation with clinical and psychometric assessments of depression (Zung, 1967).

Its popularity is also due to the fact that it is one of the rare depression scales with published normative data for aged individuals since a certain degree of intellectual impairment does not seem to preclude its use. Heiddel and Kidd (1975) used the scale with 120 nursing home residents, many of whom had intellectual impairment. However, their results suggested that a number of patients judged "senile" by the staff were actually unrecognised depressives, who scored higher than those with depression without cognitive impairment.

As its clinical application requires the use of ageappropriate norms, reliability may not be acceptable when the instrument is applied to the "old-old" (above age 70). McGarvey et al, (1982) reported that the measure's internal consistency was below usual standards when used with the "old-old", and suggested that deletion of somatic items would improve reliability in very old samples (above age 70). Sadavoy & Reiman-Sheldon (1983) explained that the Zung scale may be vulnerable to overestimating syndrome depression in the elderly because of its emphasis on physical aspects of depression. In fact, the somatic items which appear to account for most of the difference between younger and older normal persons' responses, may have different meaning for the old than for the young. As a result, because of its preponderance of somatic items (relative to those tapping psychological distress), and because some items were worded positively while others were worded negatively (necessitating frequent shifts in response sets), both the validity and the reliability of this scale have been called into question (Blumenthal, 1975). There has been an attempt to validate the Scale in the aged, but the ability of the Scale to discriminate nondepressed from depressed elderly was found to be limited (Zung & Green, 1973). Therefore, although it has been used extensively, a number of reports have indicated that it is not i'l.S satisfactory as was once thought.

GENERAL REMARKS ON THE SCALES

The primary problem with several of the self-rating scales presently available is that they were not originally designed for use with the elderly and rarely have they been properly validated in that population. Moreover, they may be too difficult for the elderly to complete by themselves. For example, the Zung scale uses a 4-point scale that may be more confusing than a yes/no format, because it involves a greater number of choices and requires the individual to make subtle discriminations.

Another important criticism is that most existing scales are heavily loaded towards measuring the somatic symptoms of depression. Althought somatic complaints are clearly part of major depressive disorders, this will not necessarily be the case in milder forms of depression. For example, the Hamilton scale tended to emphasise the somatic symptoms of depression and the Beck inventory to focus on features such as pessimism, failure and selfpunishment. The two scales are biased to measure different components of depression. Subsequent reviews (Raskin & Jarvik, 1979) of the depression-rating scales proposed primarily for adults confirmed rather limited applicability in old age. In line with this, Bolla-Wilson & Bleecker (1989) contended that the increased prevalence of depression in older adults on self-report depression scales could have been due to the report of more somatic items or physical symptoms rather than true depressive symptomatology. The shortcomings relate to the acceptability of the scales by elderly people and to the doubtful geriatric relevance of some dimensions or the absence of other.

There are also special considerations for the proper assessment of an older person. Age-related factors, such as a more defensive attitude towards psychiatric investigation, fatigue, and deficits of recent memory, can alter the properties of a scale if the formulation and design of questions and time peroid covered are not appropriate. Indeed, to the extent one is interested in screening for depression rather than formal diagnosis or description, discrimination between depressed and nondepressed persons or between different degrees of depression would seem to be the primary concern (Yesavage et al, 1983).

GERIATRIC DEPRESSION SCALE

As depression rating scales developed for younger patients are less suitable for estimating the degree of depression in older patients, an American group (Brink et al, 1982; Yesavage et al, 1983) has developed the Geriatric Depression Scale, an instrument designed specially for the assessment of subjective depression in the elderly. The 30 dichotomous items can be either rated by the patient or read to him and rated by the evaluator.

Their preliminary research suggests good correlation with an interview and observation rating scale measure of depression (the Hamilton scale) in an elderly sample. It discriminated well between groups of normals and depressives of different severity in one validation study. It has also been shown to be valid and reliable with institutionalized aged (Lesher, 1986; Parmelee, Katz & Lawton, 1989). Its capacity to differentiate depressed from nondepressed was satisfactory in a population of physically ill elderly and a population of demented elderly (Yesavage et al., 1983).

The Scale has the advantage of not being heavily loaded with physical symptom items, and of requiring only a "yes" or "no" response to each item, which may have some advantage over the 4-point ratings required on the Zung scale and the Beck inventory, when applied to older individuals. Furthermore, it does not show age or sex effects, and may prove an excellent choice as a self-report measure for assessing depression in the elderly (Bolla-Wilson & Bleecker, 1989).

CONCLUSION

A basic requirement for understanding any disease is an understanding of the distribution of the illness in the general population and the variables that determine the distribution. In psychiatry such basic information is often lacking.

Today, when increasing numbers of aged cases are seen and managed by nonpsychiatric physicians, a simple and reliable tool to assess old-age depression is needed in everyday practice. While it is obvious that no rating scale can ever replace clinical judgment and experience, it should be remembered that a good assessment instrument, in skilful hands, can become part of the therapeutic process and improve the difficult relationship with an old and depressed patient.

To this end, scales should be devised for primary care physicians to induce them to play a part in psychopathological or psychopharmacological research that will mark an initial move towards their greater receptiveness and competence in the diagnosis and therapy of geriatric depression. Probably a more suitable way of arousing their interest appears to be the use of self-rating scales. When used in epidemiological research on patients, these scales have made doctors more aware of the importance of the severity of depression, which may otherwise be underrated or scotomosed by them. The availability of self-report measures then provides another source of ·information, and could supplement interviewer assessment.

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Bernard W.K. Lau MBBS, MRCPsych, DPM. Psychiatrist in private practice. Room 703, Capitol Centre, 5-19 Jardine's Bazaar, Causeway Bay, Hong Kong.

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