Community Clinical Sciences Research Division, Faculty of Medicine Health and Biological Sciences, University of Southampton
Correspondence: Chris Thompson, Department of Mental Health, Royal South Hants Hospital, Brinton's Terrace, Southampton SO14 0YG, UK
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ABSTRACT |
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Aims Our objective was to investigate the relationship between severity and recognition of depression, and its modification by patient and practitioner characteristics.
Method An association study in multiple consecutive adult cohorts of 18 414 primary care consultations drawn from a representative sample of 156 general practitioners in Hampshire, UK.
Results There was a curvilinear relationship between the severity of depression and practitioners' ratings of depression. One case of probable depression was missed in every 28.6 consultations. Anxiety and unemployment altered the chances of recognition, but age, gender and deprivation scores did not.
Conclusions A dimensional approach to severity of depression shows that general practitioners may be better able to recognise depression than previous categorical studies have suggested. Efforts to improve the care of depression should therefore focus on doctors who have been shown to have difficulty making the diagnosis and on improving the treatment of identified patients.
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INTRODUCTION |
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METHOD |
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All general practices in Hampshire (n=224) were invited to take part. One hundred and fifty-two GPs in 55 practices completed the study and, although they were to some degree self-selected, were shown to be representative of Hampshire in their list size, the number of principals, patients per principal, the proportion of women and the proportion of part-time partners. These 152 GPs and their attending patients formed the sample for this study.
Measures
Self-ratings of depression and anxiety
In each of four screening phases over 2 years researchers distributed the
Hospital Anxiety and Depression (HAD) scale to consecutive attenders aged 16
years and above in the practice waiting room during routine surgeries. This
continued until at least 30 patients had been screened per GP in multi-partner
practices and 40 for sole partner GPs. The HAD scale is a self-administered
rating scale with 14 questions yielding separate scores for anxiety and
depression (Zigmond & Snaith,
1983). It has been validated as a screening tool in general
practice (Wilkinson & Barczak,
1988), and the sub-scales appear to provide a valid measure of the
severity of mood disorders in primary care
(Upadhyaya & Stanley,
1993). A score 8 on the HAD depression sub-scale (HAD-D) is
the conventional threshold for identifying possible depression.
GPs' age, gender, qualifications and working time were ascertained at
recruitment to the study.
Patients were also asked to record their gender, date of birth and employment status.
GP ratings
Blind to the result of the HAD scale, practitioners completed a four-point
rating of depression for each patient. Ratings were: 0, no depression
detected; 1, sub-clinical emotional disturbance; 2, clinically significant
depressive illness mild; 3, clinically significant depressive illness
moderate or severe.
In the original study the recognition of depression was defined as the
proportion of patients with a score 8 on the HADD sub-scale who
were scored
2 on the GP scale. In this study an analysis of recognition
rates for each HADD score was carried out and the effects on
recognition and false positive rates of varying the threshold were
explored.
Subjects
Each attender was eligible to take part once during each of four phases of
the trial. Acceptance by those approached was 89%, 20 832 attenders were
screened. All patients attending more than once therefore had their second
attendance removed. Analysis was carried out on 18 414 consultations by unique
patients (85.4%).
Socio-economic status
Underprivileged area (Jarman,
1983) scores were allocated to practices according to the
electoral ward of the surgery address. The score has been shown to account for
almost half the variance in the prevalence of depressive symptoms between
practices in this study population (Ostler
et al, 2001).
Hypotheses
Practitioner characteristics
The average GP case recognition rate at a standard HAD scale threshold of
7/8 will be around 30-40%, consistent with previous literature. GP
characteristics such as gender and length of time in practice will influence
the recognition of depressive symptoms.
Patient characteristics
More severe depressive symptoms will be recognised more frequently. A
sensitivity analysis will identify the effect on recognition rates of changing
the threshold for case definition. Low anxiety scores, male gender and
increasing age will reduce recognition rates independently of depression
scores.
Socio-economic setting
Underprivileged area score might be expected to influence recognition rate
in two contrasting ways. Taking the GP's interview with the patient as a
diagnostic test, their performance might be expected to be more sensitive, but
less specific, in high deprivation areas where prevalence of depression is
higher (Kraemer, 1988).
Alternatively, GPs in high deprivation areas might more often attribute
depressive symptoms to social conditions rather than illness thus
reducing recognition rates. The relative effect of these two contrasting
influences is unknown.
Statistical analysis
Diagnostic sensitivity (Boardman,
1987; Goldberg & Huxley,
1992) was defined for each GP as the proportion of patients with
an HADD 8 who were rated as scoring 2 or 3 by the GP. For each
value of the HADD score from 0 to 21, the proportion of patients with a
GP rating of 2 or 3 was calculated. Logistic regression was used to model the
data, generating equations in the form
logit (p)=c+(b*HADD)
where p is the probability of a positive GP score (2).
Recognition (or sensitivity) curves were plotted for patients grouped by age (16-64 v. 65+ years), gender, HADA sub-scale (0-10 v. 11-21) and underprivileged area score (<-10, -10 to +10, >10). These thresholds were adopted prior to analysis. Finally, multiple logistic regression was used to examine the effect of controlling for the severity of depression and anxiety on the recognition of screened cases by gender, age and occupational group of patients.
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RESULTS |
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Practitioner characteristics and recognition rates
The mean recognition rate (sensitivity) across all practitioners was 36.1%
(95% CI 33.8-38.4) with specificity 91.5% (95% CI 90.6-92.5) and =0.31
(0.28-0.33), consistent with previous studies.
Practitioners rated a mean of 13.6% (s.d.=6.9%) patients as being depressed with extremes of 0/95 (0%) and 28/73 (38.4%). Median diagnostic sensitivity was 0.67 (interquartile range 0.38), only slightly lower than the figure of 0.78 quoted by Goldberg et al (1982) for the recognition of psychological morbidity by British GPs.
Part-time practitioners were less likely to diagnose depression (median recognition rates 0.57) than full-time GPs (median 0.70, MannWhitney U-test, P=0.033) and they also tended to work in less deprived areas (mean underprivileged area score difference -9.00, t-test P=0.004). There was no significant effect on recognition of GPs' gender (MannWhitney U-test P=0.67), length of time working in general practice (rs=0.111, P=0.172), prevalence rate in the patient sample (rs=-0.101, P=0.216) or underprivileged area score (rs=-0.099, P=0.221).
Depression severity and recognition rate
Figure 1 shows the
relationship between severity of depressive symptoms and recognition rates.
Apart from the very high scores at 19-21, where there are few cases, there is
a strong relationship between HADD sub-scale score and recognition.
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Using the conventional analysis of the number of cases that are missed, the performance of the GPs in this study was similar to other reports (Docherty, 1997). At the threshold of eight or above 64.7% of cases were missed. However, the dimensional approach to the data demonstrates that at progressively higher scores the lower prevalence and the increasing recognition rate makes this simple analysis misleading. This is because the proportion of missed cases drops markedly with small increments of the threshold score and the total number of cases also falls. Thus, 72.6% of all missed cases scored 8-10 (mild or doubtful depression).
This dimensional approach shows the critical effect of the choice of threshold for defining the case of depression. It can be illustrated by examining the effect of a progressive rise, by a single point at a time, in the threshold for case definition. Table 2 shows that the proportion of missed cases diminishes as the threshold increases, which is not surprising although the rate at which it diminishes may be. In addition (bearing in mind the difficulty of identifying a `gold standard diagnosis for depression) wherever the threshold is set, 30-50% of all missed cases lie only one point above that threshold.
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The results of recognition rate studies are usually presented as the proportion of true cases that are missed. However, a better indicator of the acceptability of practice would set the denominator as the total consultations, that is, 18 414, rather than the number of cases. On this analysis 12.9% of all consultations contain a failure to identify a possible or doubtful case (33.6% of which are one point above that threshold at the time of interview). Some 3.5% of consultations contain a failure to identify a probable case (of which 34.7% are one point above that threshold at the time of interview). Thus at this more robust, higher threshold one patient with a probable depression is missed every 28.6 consultations without allowing for error in the questionnaire.
GPs may recognise depressive symptoms but categorise them as sub-clinical emotional symptoms (score one on their questionnaire), a clinical judgement that may be appropriate at borderline levels of severity. Of those patients with probable depression 75.9% were rated by the GP as having some emotional disturbance (score one or above). Figure 2 shows the effect of different recognition thresholds on the relationship between recognition and severity. Using a score of one as the criterion the number needed to screen before a case of probable depression is missed increases from one in 28.6 to one in 58 consultations.
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Factors affecting the relationship between recognition and
severity
Figure 3 shows that patients
with higher anxiety scores were more likely to be recognised as depressed at
all levels of depression severity. There was a moderate correlation between
HAD scale anxiety and depression scores (r=0.599,
P<0.0005). The effect of adjusting for severity of depression and
anxiety on the recognition of screened cases is shown in
Table 3. Before adjusting for
severity, women, the unemployed and those who were permanently unable to work
were significantly more likely to be recognised, while the elderly and retired
patients were more likely to be missed. Adjusting for depression severity
eliminated the significance of being permanently unable to work so their
higher rate of recognition is explained by more severe symptoms. Adjustment
for both anxiety and depression scores eliminated the significance of gender,
age and retirement status. Thus, after adjusting for the severity of
depression and anxiety symptoms the only remaining bias was an increased
sensitivity to depression among the unemployed and those temporarily away from
work, possibly mediated by prior knowledge of treated depression.
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DISCUSSION |
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The study might be criticised for not employing a diagnosis of depression based on a research interview against which to judge practitioners' skills rather than a self-rating questionnaire. Such an approach would have appropriately eliminated some patients with depressive symptoms whose primary diagnosis was not depression and would have set a longer duration of symptoms for identification than the HAD scale response period. We discuss below the value of the dimensional approach, but in addition the size of this study rendered full diagnostic procedures impractical. They would also have introduced observer bias in the interpretation of the depressive symptoms that is not present when dealing with self-ratings. The patients included only those who were ambulatory and able to attend the doctors' practice premises, excluding potentially depressed patients among the chronically ill and disabled group, who were therefore under-represented.
Findings in the context of the previous literature
The recognition of depression by GPs has been a subject of investigation in
many studies, all of which have suggested low true positive rates of
identification. Some of these have previously shown that recognition is
dependent on severity (Coyne et
al, 1995; Ormel &
Tiemens, 1995; Dowrick,
1995), a conclusion with which we concur. We disagree, however,
with previous research suggesting that there is better recognition of
depression in women and the middle-aged, and poorer recognition in the elderly
(Boardman, 1987;
Katona et al, 1995).
These effects may have been significantly confounded by severity of illness
and after allowing for this we have shown that diagnosis is based on symptoms
rather than stereotypes. It is also reassuring that practitioners working in
deprived areas were not biased against a diagnosis of depression owing to
reduced expectations of patients' quality of life. Indeed they appear to be
somewhat over-sensitive to the possibility of depression in patients who were
currently unemployed.
Our findings, however, go further than the prior literature in two ways. First, we calculate non-recognition rates by reference to the consulting population, rather than as a proportion of the number of patients with depression. Second, in dimensional conditions such as depression, apparently low rates of diagnosis can be produced by adopting a low score as a case threshold. We have shown that the choice of threshold critically affects the recognition rate because of the diminishing prevalence of higher scores combined with increasing recognition, thus explaining the wide variations of previous estimates. Furthermore, some of the one-third of missed cases that lie only just above any given threshold on the HADD sub-scale may be true negatives since all questionnaires and diagnostic procedures have rating errors. In addition, these recognition rates are obtained from a single 9-minute consultation, and the GP's prior knowledge of the patient. They must be taken together with evidence that many missed patients are diagnosed correctly at a subsequent visit (Ormel & Tiemens, 1995).
Implications, for practice and education
One criticism of our study might be the absence of a gold
standard diagnostic criterion for depression. We believe this criticism
would be hard to sustain because psychiatric diagnostic categories are rarely
used routinely by GPs despite their need to make some dichotomous decisions,
for example whether or not to treat with anti-depressants. This may be because
of the absence of clear validity data for DSM and ICD syndromes in primary
care a category such as major depressive disorder having no
dichotomous relationship to clinical disability, need for treatment or level
of risk. In such a situation a dimensional approach has greater
epidemiological validity then a categorical one since it makes fewer
assumptions. The importance of this dimensional view of depression is
strengthened by the evidence that milder, so-called sub-syndromal symptoms are
very common and are associated with considerable health and social problems
(Judd et al,
1996).
An appropriate criterion for a gold standard definition would be validated by reference to evidence of treatment benefit and this may vary from one treatment to another depending on the definitions of treatment and of acceptable benefit. If one were to become available in the future it would make a dichotomous approach more tenable since it would demonstrate a tangibly impaired access to effective treatment as a result of missed diagnoses. Even in the absence of this evidence, however, it is reasonably safe to assume from our findings that increasing the sensitivity of GPs to depression through educational interventions will also increase the false positive diagnostic rate of some hypothetically valid depressive entity with the consequent dangers of unnecessary treatment. Since the size of the non-depressed population is larger than that of the depressed group any shift of the recognition point to the left will lead to a greater increase in the numbers of non-depressed unnecessarily treated than in the numbers of patients with depression correctly treated. In this regard, the difference in the recognition curve between sub-clinical emotional disturbance and clinically significant depression demonstrates that GPs are using their clinical judgement in recognising emotional disturbance that they believe does not require medical intervention. These results should also be placed in the broader practice perspective. Patients often present multiple ill-defined complaints and GPs rarely address mental health in isolation from other problems. Indeed, focusing on mild depressive symptoms has an opportunity cost, leaving less time for possibly more pressing demands in the relatively short time of the consultation (Klinkman, 1997). There is little evidence for the efficacy of intervention in milder depressive syndromes, and many resolve spontaneously so GPs may reasonably judge that diagnosis is not critical in these borderline states (Paykel & Priest, 1992).
Taking these factors into account it seems likely that the recognition rates of depression in general practice are not so poor as has been claimed in the past. Interventions that aim to improve GPs' recognition of depression face a difficult task if they are not also to reduce specificity and lead to potentially unnecessary treatment. Educational and research programmes should therefore concentrate primarily on targeting under-performing practitioners and enabling the better treatment of diagnosed patients (Thompson, 1999).
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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REFERENCES |
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Boardman, A. P. (1987) The General Health Questionnaire and the detection of emotional disorder by general practitioners. A replicated study. British Journal of Psychiatry, 151, 373 -381.[Abstract]
Bridges, K. W. & Goldberg, D. P. (1985) Somatic presentation of DSM-III psychiatric disorders in primary care. Journal of Psychosomatic Research, 29, 563 -569.[CrossRef][Medline]
Coyne, J. C., Schwenk, T. L. & Fechner-Bates, S. (1995) Non-detection of depression by primary care physicians reconsidered. General Hospital Psychiatry, 17, 3-12.[CrossRef][Medline]
Docherty, J. D. (1997) Barriers to the diagnosis of depression in primary care. Journal of Clinical Psychiatry, 58, 5 -10.[Medline]
Dowrick, C. F. (1995) Case or continuum? Analysing general practitioners' ability to detect depression. Primary Care Psychiatry, 1, 255-257.
Goldberg, D. & Huxley, P. (1992) Common Mental Disorders. A Bio-Social Model. London: Routledge.
Goldberg, D. & Lecrubier, Y. (1995) Form and frequency of mental disorders across centres. In Mental Illness in General Health Care (eds T. B. Üstün & N. Sartorius), pp. 323-334. Chichester: John Wiley & Sons.
Goldberg, D., Steele, J. J., Johnson, A., et al (1982) Ability of primary care physicians to make accurate ratings of psychiatric symptoms. Archives of General Psychiatry, 39, 829 -833.[Abstract]
Jarman, B. (1983) Identification of underprivileged areas. BMJ, 286, 1705 -1709.[Medline]
Judd, L. L., Paulus, M. P., Wells, K. B., et al (1996) Socio-economic burden of sub-syndromal depressive symptoms and major depression in a sample of the general population. American Journal of Psychiatry, 153, 1411 -1417.[Abstract]
Katona, C., Freeling, P., Hinchcliffe, K., et al (1995) Recognition and management of depression in late life in general practice: consensus statement. Primary Care Psychiatry, 1, 107 -113.
Kirmayer, L. J., Robbins, J. M., Dworkind, M., et al (1993) Somatization and the recognition of depression and anxiety in primary care. American Journal of Psychiatry, 150, 734 -741.[Abstract]
Klinkman, M. S. (1997) Competing demands in psychosocial care. A model for the identification and treatment of depressive disorders in primary care. General Hospital Psychiatry, 19 98 -111.[CrossRef][Medline]
Kraemer, H. C. (1988) Assessment of 2 x 2 associations: generalization of signal-detection methodology. American Statistician, 42, 37-49.
Marks, J. N., Goldberg, D. P. & Hillier, V. F. (1979) Determinants of the ability of general practitioners to detect psychiatric illness. Psychological Medicine, 9, 337-353.[Medline]
Odell, S. M., Surtees, P. G., Wainwright, N. W. J., et al (1997) Determinants of general practitioner recognition of psychological problems in a multi-ethnic inner-city health district. British Journal of Psychiatry, 171, 537 -541.[Abstract]
Ormel, J. & Tiemens, B. (1995) Recognition and treatment of mental illness in primary care. Towards a better understanding of a multifaceted problem. General Hospital Psychiatry, 17, 160 -164.[CrossRef][Medline]
Ormel, J., Van Den Brink, W., Koeter, M. W. J., et al (1990) Recognition, management and outcome of psychological disorders in primary care: a naturalistic follow-up study. Psychological Medicine, 20, 909 -923.[Medline]
Ostler, K., Thompson, C., Kinmonth, A.-L. K., et al
(2001) Influence of socio-economic deprivation on the
prevalence and outcome of depression in primary care. The Hampshire Depression
Project. British Journal of Psychiatry,
178, 12-17.
Paykel, E. S. & Priest, R. G. (1992) Recognition and management of depression in general practice: consensus statement. BMJ, 305, 1198 -1202.[Medline]
Ronalds, C., Creed, F., Stone, K., et al (1997) Outcome of anxiety and depressive disorders in primary care. British Journal of Psychiatry, 171, 427 -433.[Abstract]
Sartorius, N., Ustun, T. B., Lecrubier, Y., et al (1996) Depression comorbid with anxiety: Results from the WHO study on psychological disorders in primary health care. British Journal of Psychiatry, 168 (suppl. 30), 38-43.[Abstract]
Simon, G. E. & Von Korff, M. (1995) Recognition, management, and outcomes of depression in primary care. Archives of Family Medicine, 4, 99-105.[Abstract]
Tiemens, B. G., Ormel, J. & Simon, G. E. (1996) Occurrence, recognition, and outcome of psychological disorders in primary care. American Journal of Psychiatry, 153, 636 -644.[Abstract]
Thompson, C. (1999) The Clinical Standards Advisory Group Study of Services for Patients with Depression. London: Department of Health.
Thompson, C., Kinmonth, A. L., Stevens, L., et al (2000) Randomised-controlled trial of a clinical practice guideline and practice based education on the detection and outcome of depression in primary care; The Hampshire Depression Project. Lancet, 355, 185 -191.[CrossRef][Medline]
Upadhyaya, A. K. & Stanley, I. (1993) Hospital anxiety depression scale. British Journal of General Practice, 43, 349 -350.
Von Korff, M., Shapiro, S., Burke, J. D., et al (1987) Anxiety and depression in a primary care clinic. Comparison of diagnostic interview schedule, General Health Questionnaire and practitioner assessments. Archives of General Psychiatry, 44, 152 -156.[Abstract]
Wilkinson, M. J. B. & Barczak, P. (1988) Psychiatric screening in general practice: comparison of the general health questionnaire and the hospital anxiety depression scale. Journal of the Royal College of General Practitioners, 38, 311 -313.[Medline]
World Health Organization (1992) The ICD-10 Classification of Mental and Behavioural Disorders. Geneva: WHO.
Zigmond, A. S., & Snaith, R. P. (1983) The Hospital Anxiety and Depression Scale. Acta Psychiatrica Scandinavica, 67, 361 -370.[Medline]
Received for publication August 7, 2000. Revision received January 18, 2001. Accepted for publication January 23, 2001.