Prevalence of depression, quality of life and antidepressant treatment in the Danish General Suburban Population Study CHRISTINA ELLERVIK, JAN KVETNY, KAJ SPARLE CHRISTENSEN, MOGENS VESTERGAARD, PER BECH
Ellervik C, Kvetny J, Christensen KS, Vestergaard M, Bech P. Prevalence of depression, quality of life and antidepressant treatment in the Danish General Suburban Population Study. Nord J Psychiatry 2014;68:507–512. Background: The Danish General Suburban Population Study (GESUS), the objective of which is to facilitate epidemiological and genetic research, has included the Major Depression Inventory (MDI) and the WHO-Five Well-Being Index (WHO-5) among the medical health questionnaires. We were thus in a position to compare the 2-week prevalence of ICD-10 depression in the period from 2010 to 2012 with our previous Danish general population study from 2003, in which the MDI was also included. Aims: The aim of our analysis was not only to evaluate the point prevalence of ICD-10 depression but also to describe the prevalence of antidepressants received by the respondents in the GESUS study and the correspondence to their subjective well-being on the WHO-5 questionnaire. Methods: To evaluate the validity (scalability) of the MDI and the WHO-5 in the GESUS study we performed the non-parametric Mokken analysis. The scalability of the MDI and the WHO-5 was quite acceptable. Results: In total, 14,787 respondents were available from a response rate of 50%. The 2-week prevalence of ICD-10 depression was 2.3%, which is rather similar to the 2.8% in our 2003 study. The rate of people receiving antidepressants increased consistently with increasing severity of ICD-10 depression. Conclusion: This study has confirmed that the use of the MDI to obtain an ICD-10 depression diagnosis gives rather conservative estimates of the 2-week prevalence of depression in the Danish general population. The prescription of antidepressants depends on the severity of the ICD-10 depression diagnosis. • Depressive illness, Major Depression Inventory, WHO-5. Per Bech, M.D., Professor of Psychiatry, Psychiatric Research Unit, Psychiatric Centre North Zealand, Copenhagen University Hospital, Denmark, E-mail: [email protected]; Accepted 16 December 2013.
T
he aim of the Danish General Suburban Population Study (GESUS) is to facilitate epidemiological and genetic research using information from both selfadministrated questionnaires and from health examinations, biochemical measurements, genetic variants and nationwide registers for somatic disorders and mortality (1). The questionnaires contain items about medical conditions as well as mental health, e.g. the WHO-Five WellBeing scale (2, 3) and the Major Depression Inventory (MDI) (2, 4). In the analysis to be reported here, we have focussed on the WHO-5, the MDI and other depression-oriented items in the medical questionnaires (“Has your family doctor ever told you that you have suffered from depressive illness?” or “Do you currently receive antidepressant medication?”). The objective of our study has been to evaluate the point prevalence (past 2 weeks)
© 2014 Informa Healthcare
of ICD-10 depression, the lifetime prevalence of depressive illness, and the proportion of persons who were prescribed antidepressant medication during both the acute depression state and the long-term therapy of depressive illness. Finally, we used the WHO-5 results to compare the level of subjective quality of life in depressed and non-depressed persons.
Material and Methods GESUS was initiated in January 2010; enrolment is still ongoing. It is a cross-sectional study of the adult Danish suburban population in Naestved Municipality (approximately 70 km south of Copenhagen). The criteria for invitation are adults with a Danish citizenship who are resident in Denmark. All people aged 30 years and a DOI: 10.3109/08039488.2013.877074
C ELLERVIK ET AL.
randomly selected 25% of persons aged 20–30 years were invited by mail in numerical order, starting with citizens born on the 1st in every month and continuing. If individuals had not responded within 3 weeks of their scheduled attendance period, a reminder was sent with a new scheduled period. For the analysis to be reported here, we include participants from January 2010 to December 2012, from whom 50% of the contacted individuals responded. The study was approved by the appropriate institutional review boards and ethical committees (SJ-113, SJ-114), and reported to the Danish Data Protection Agency. Written informed consent was obtained from all participants. The investigation is in accordance with the principles of the Declaration of Helsinki. The GESUS study questionnaire can be viewed at www.p3gobservatory.org/catalogue.htm;jsessionid ACE6E593F10B80573 D64E965FA2DB3D8?measureId 38.
Self-administrated questionnaires The medical health questionnaire was similar to the one used for the Copenhagen City Heart Study (5). From this medical health questionnaire, we have especially focussed on the following items: •
•
Has your family doctor ever told you that you are suffering from or previously have suffered from depressive illness? If so, how old were you when the illness started? Do you currently take antidepressive medication?
The MDI is a self-administrated questionnaire covering the symptom criteria of clinical depression for both DSM-IV (6) and ICD-10 (7). The MDI has a double function as it can be used both as a diagnostic aid and as a measure of depression severity (4). The total score of the MDI ranges from 0 (no depression) to 50 (extreme depression). The ICD-10 algorithm for depression is used to categorise into mild (an MDI score of 21–25), moderate (an MDI score of 26–30) and severe categories (an MDI score of 31) (2). The WHO-5 questionnaire is a psychological wellbeing scale. Like the MDI, the time frame (window) is the previous 2 weeks. The WHO-5 includes the following items: being cheerful and in good spirits; being calm and relaxed; feeling active and vigorous; feeling fresh and rested when waking up in the morning; and having interest in the day-to-day activities. Each item is scored from 0 (at no time) to 5 (all of the time). The theoretical raw score range is consequently from 0 to 25. However, by multiplying the raw score by 4, the recommended score range goes from 0 worst imaginable quality of life to 100 best imaginable quality of life. In the general population surveys, the mean WHO-5 is approximately 70 (2). When screening for depression, a WHO-5 score 50 is used.
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Psychometric analysis The non-parametric Mokken analysis has been used to test the scalability of MDI and WHO-5 (2). The Mokken analysis (8) is based on Loevinger’s coefficient of homogeneity (9). We have used the program for polytomous items (10). According to Mokken (8), a coefficient of homogeneity between 0.30 and 0.39 is only just acceptable; a coefficient of homogeneity between 0.40 and 0.49 is acceptable for scalability.
Results Between January 2010 and December 2012, the GESUS consisted of 16,703 responders, but due to incomplete answers on the MDI, the WHO-5 or the items concerning lifetime depression or antidepressant medication, 14,787 responders were available for the analysis, 7971 females (54%) and 6816 males (46%). The mean age for all 14,787 persons was 53.5 13.3 years; for females 52.9 13.2 and for males 54.1 13.3. The coefficient of homogeneity by the Mokken analysis was 0.49 for the MDI and 0.64 for the WHO-5. In other words, both scales showed adequate measures of scalability (coefficient of homogeneity above 0.40). In total 1847 or 12.5% had been informed by their family doctor that they suffered from depressive illness [1259 (15.8%) females and 588 (8.6%) males]. In total 345 (2.3%) of the responders had, when using the ICD-10 algorithm for depression according to MDI, a current depression [223 (2.8%) females and 122 (1.8%) males]. Using the MDI summed total score, 376 or 2.5% had a current depression (261 or 3.3% females and 115 or 1.7% males) with a score of 26 or more. Table 1 shows that of the 1847 persons with a history of depressive illness according to the family doctor, 185 had a current ICD-10 diagnosis of depression (mild 64, moderate 67 and severe 54) according to the MDI, i.e. a 2-week prevalence of 10% of all persons with depressive illness. Table 1 shows the distribution of these 1847 persons according to their current ICD-10 depression diagnosis (none, mild, moderate and severe) in respect to WHO-5 and percentage of antidepressants. No statistically significant difference as regards the WHO-5 score or the proportion of persons in antidepressant treatment was found when females and males were compared. The mean WHO-5 score decreased significantly across the different ICD-10 depression categories (P 0.01) from no depression (60.4), mild (28.7), moderate (22.9) and severe (16.5). The percentage of persons receiving antidepressants increased significantly (P 0.01) from 36.9% among participants with a history of depression but no current ICD-10 depression to 68.5% among those with a severe ICD-10 depression. Table 2 shows the results for all 14,787 respondents regarding the current ICD-10 categories of no NORD J PSYCHIATRY·VOL 68 NO 7·2014
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Table 1. The WHO-Five Well-Being Index (WHO-5) scores [mean (standard deviation, s)] and the corresponding percentage of prescription of antidepressants in respondents with depressive illness. Current ICD-10 depression, according to MDI No current ICD-10 depression n 1662 Females, n 1132 Males, n 530 Mild ICD-10 depression n 64 Females, n 40 Males, n 24 Moderate ICD-10 depression n 67 Females, n 49 Males, n 18 Severe ICD-10 depression n 54 Females, n 38 Males, n 16
WHO-5, mean (s)
% Antidepressant
90 80
36.9% 38.4% 33.6%
60
28.7 (17.1) 28.6 (18.9) 28.8 (14.1)
51.6% 57.5% 41.7%
30
22.9 (13.0) 21.4 (10.8) 26.9 (17.3)
49.3% 44.9% 61.1%
16.5 (15.4) 18.3 (17.4) 12.3 (7.9)
68.5% 68.4% 68.8%
Females
50
Males
40
All
20 10
Table 2. The WHO-Five Well-Being Index (WHO-5) scores [mean (standard deviation, s)] and the corresponding percentage of prescription of antidepressants in the total group of respondents. WHO-5, mean (s)
% Antidepressant
0
None
Mild
Moderate
Severe
ICD-10 depression severity
Fig. 1. Mean WHO-Five Well-Being Index (WHO-5) scores within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the respondents with depressive illness (n 1847).
depression (24.5) and severe depression (16.0). The percentage of persons receiving antidepressants increased significantly (P 0.01) from no depression (4.7%), mild depression (22.3%), moderate depression (29.8%) and severe depression (50.0%). These results are graphically illustrated in Figs 1–4. When comparing Tables 1 and 2, it appears that patients with ICD-10 diagnoses of severe depression had consulted their family doctors in 54 out of 74 cases (73%). For moderate ICD-10 depression, this was 67 out of 144 cases (59%), whereas for mild ICD-10 depression it was 64 of 157 cases (41%). To explore this difference WHO-5 100 90
70.6 (17.1) 69.7 (17.5) 71.8 (16.5)
4.7% 6.1% 3.0%
30.0 (16.0) 30.1 (17.4) 30.0 (14.1)
22.3% 28.7% 14.3%
24.5 (12.7) 23.0 (11.1) 28.4 (15.6)
29.8% 27.7% 35.5%
80 70 60
Females
50
Males
40
All
30 20
16.0 (14.4) 17.1 (15.9) 13.1 (9.3)
MDI, Major Depression Inventory; s, standard deviation. All respondents, n 14,787. NORD J PSYCHIATRY·VOL 68 NO 7·2014
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60.4 (19.9) 59.8 (20.0) 61.6 (19.7)
(n 14,442), mild (n 157), moderate (n 114 and severe depression (n 74) in respect to WHO-5 and the proportion of persons in treatment with antidepressants. No statistically significant difference with regard to WHO-5 or percentage of antidepressants was found when females and males were compared. Across the different ICD-10 categories, the mean WHO-5 decreased significantly (P 0.01) from no depression (70.6), mild depression (30.0), moderate
No current ICD-10 depression n 14,442 Females, n 7748 Males, n 6694 Mild ICD-10 depression n 157 Females, n 87 Males, n 70 Moderate ICD-10 depression n 114 Females, n 83 Males, n 31 Severe ICD-10 depression n 74 Females, n 53 Males, n 21
WHO-5
70
MDI, Major Depression Inventory. Depressive illness, n 1847.
Current ICD-10 depression, according to MDI
DEPRESSION IN THE GESUS STUDY
50.0% 49.1% 52.4%
10 0 None
Mild
Moderate
Severe
ICD-10 depression severity
Fig. 2. Mean WHO-Five Well-Being Index (WHO-5) scores within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the total group of respondents (n 14,787).
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Percent antidepressants
100 90 80 70 60 50 40 30 20 10 0
100 90 80 70 Females Males All
60
Females
50
Males
40
All
30 20 10 None
Mild Moderate Severe ICD-10 depression severity
0 None
Fig. 3. The percentage of antidepressants received within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the respondents with depressive illness (n 1847).
between 73%, 59% and 41% for these patients who had consulted their family doctors, we performed an analysis (Table 3) in which age, gender and chronic medical conditions were taken into consideration. In connection with our question: “Has your family doctor ever told you that you have suffered from such medical conditions as cancer, stroke, diabetes etc.?” (Table 3), we used this hierarchy of these six conditions as listed in Table 3. If a person had more than one of the conditions, we only counted the condition with the highest ranking in the hierarchy. Thus, if a person answered yes to having both diabetes and iron deficiency, it was then diabetes that counted in Table 3. From Table 3 it can be seen that more females than males had contact with their family doctor in the moderate to severe depression group (P 0.02). For the chronic somatic conditions, the contact
Mild
Moderate
Severe
ICD-10 depression severity
Fig. 4. The percentage of antidepressants received within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the total group of respondents (n 14,787).
between patients and their family doctor were most frequent for severe depression (P 0.01). Table 4 shows the association between MDI summed total score and WHO-5 mean scores using all 14,787 observations. Table 5 shows a comparison with our previous general Danish population study with MDI (2). The 2-week prevalence of ICD-10 depression using the algorithm in MDI was 2.3% versus 2.8%, i.e. rather similar. When using the total MDI scores, the 2-week prevalence in the GESUS was only just lower than in the general population. The mean MDI score for each month was around 6.5 (6.6) through the 12 months (P 0.10)
Table 3. Age, gender and chronic medical conditions in depressed patients with and without contact with their family doctor. Severe ICD-10 depression (n 74) Contact (n 54) Age, mean (s) in years % Females Somatic conditions Cancer Stroke Diabetes Hyperthyroidism Angina pectoris Iron deficiency Total (number of patients) % Somatic condition
No contact (n 20)
Moderate ICD-10 depression (n 114) Contact (n 67)
51.7 (13.6) 52.2 (14.0) 50.8 (12.0) 70.4% 75.0% 73.1% 6 3 5 4 4 8 30 55.6%
1 0 0 1 0 1 3 15.0%
8 4 3 2 4 7 28 41.8%
No contact (n 47) 50.6 (15.3) 72.3% 4 0 2 0 3 4 13 27.7%
Mild ICD-10 depression (n 157) Contact (n 64)
No contact (n 93)
P
54.7 (13.1) 50.3 (13.5) 0.32 62.5% 50.1% 0.02 5 3 4 2 4 5 23 35.9%
8 1 5 2 2 6 24 25.8%
0.01
s, standard deviation.
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Table 4. A standardization of the Major Depression Inventory (MDI) using WHO-Five Well-Being Index (WHO-5) scores [mean (standard deviation, s)] as index. WHO-5 mean (s) MDI 0–9 MDI 10–14 MDI 15–20 (doubtful depression) MDI 21–25 (mild depression) MDI 26–30 (moderate depression) MDI 31–50 (severe depression)
86.8 (10.4) 59.7 (14.7) 48.0 (14.6) 40.7 (16.0) 33.2 (16.7) 28.3 (14.0)
s, standard deviation.
Discussion In this large population-based study of younger adults, the 2-week prevalence of ICD-10 depression was 2.3% (women: 2.8% versus men: 1.8%) and the proportion of persons with a history of depressive illness was 12.5% (women 15.8% versus men: 8.6%). The mean WHO-5 score decreased and the percentage of people receiving antidepressants increased consistently by increasing severity of the ICD-10 depression categories for both genders. The 2-week prevalence of the MDI based ICD-10 diagnosis of depression of 2.3% was rather similar to our previous general population study from 2003 (Table 4). It was also similar to the 3-month prevalence of the ICD-10 diagnosis of depression found by Grynderup et al. (11) who obtained a rate of 2.4% among Danish public employees when using the SCAN interview (12). The 12-month prevalence of DSM-IV major depression in six European countries (13) was 3.9% (with 5.0% for females and 1.9% for males). In this latter study, the Composite International Diagnostic Interview (CIDI) was used (14). However, in the Norwegian Kringlen et al. (15) study, the 12-month prevalence of DSM-III-R major depression was 7.3%. Self-rated depression scales such as the MDI or the Beck Depression Inventory (16) may eliminate many of the problems of inter-rater reliability Table 5. A comparison between the present study (GESUS) and our previous general Danish population study carried out in 2003. GESUS, n 14,787 Responder rate Age, years mean (s) Females Males % females Coefficient of homogeneity ICD-10 depression MDI 20 MDI 25
General Danish population study from 2003 (ref. 2), n 1867
50% 52.9 (13.2) 54.1 (13.3) 53.9% 0.49 2.3% 4.8% 2.5%
(17). The MDI coefficient of homogeneity (Table 4) showed a good scalability, indicating an acceptable response pattern in our MDI studies; this is also to be found in the study by Konstantinidis et al. (18). Our results as to the prevalence of ICD-10 depression according to the MDI algorithm, as well as the summed MDI raw score, are very similar to our general Danish population study from 2003 (Table 4). With regard to the lifetime prevalence of depressive illness, our rates of 15.8% for females and 8.6% for males were rather similar to those in the Alonso et al. (13) study, which obtained a lifetime prevalence of 16.5% for females and 8.9% for males. The study by Kringlen et al. (15) showed higher lifetimes rates, namely approximately 24% for females and 10% for males, i.e. especially for females. However, in all these studies, females had a higher lifetime prevalence of depression than males. The great majority of patients with a current, severe ICD-10 diagnosis of depression had consulted their family doctors in 73% of the cases. Our socio-demographic analysis seems to support Mechanic’s original observation (19) that patients with chronic medical conditions are more likely than other persons to seek help from their family doctors when under social adversity. As discussed by Bebbington et al. (20), this illness behaviour is especially in operation if the help-seeking persons have no expectation of any termination of their social adversity. Using the WHO-5 as a measure of positive wellbeing, we could demonstrate that for people with a current depressive episode, the WHO-5 sum score was significant lower among persons on antidepressant medication than in those not receiving antidepressants. This is in agreement with the study by Angst (21), who found in a general population study in Zürich that persons consulting their family doctor with depression are more ill than those not consulting their family doctor when depressed. In summary, the MDI demonstrated conservative prevalence estimates of ICD-10 depression in a large Danish general population sample, thus supporting its use for diagnostic evaluation of depression, as recommended by the Danish National Board of Health (22). Further studies are needed to evaluate the optimal administration procedure and validity of the MDI in primary care settings (23).
68% 53.1 (16.4) 55.9 (16.3) 52.9% 0.47 2.8% 6.2% 3.7%
s, standard deviation; MDI, Major Depression Inventory. NORD J PSYCHIATRY·VOL 68 NO 7·2014
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Acknowledgements—The GESUS study received support from Johan and Lise Boserup Foundation; TrygFonden; Det Kommunale Momsfond; Johannes Fog’s Foundation; Region Zealand; Region Zealand Foundation; Naestved Hospital; Naestved Hospital Foundation; the National Board of Health; Danish Agency for Science, Technology and Innovation.
Disclosure of interest: Kaj Sparle Christensen and Mogens Vestergaard are supported in part by an unrestricted grant
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from the Lundbeck Foundation. Christina Ellervik, Jan Kvetny and Per Bech have none to disclose.
14. 15.
References 1. Bergholdt HK, Bathum L, Kvetny J, Rasmussen DB, Moldow B, Hoeg T, et al. Study design, participation and characteristics of the Danish General Suburban Population Study. Dan Med J 2013;60:A4693. 2. Bech P. Clinical psychometrics. Oxford: Wiley Blackwell; 2012. 3. Bech P, Olsen L, Kjoller M, Rasmussen N. Measuring well-being rather than the absence of distress symptoms: A comparison of the SF-36 mental health subscale and the WHO-Five well-being scale. Int J Meth Psychiatr Res 2003;12:85–91. 4. Bech P, Rasmussen NA, Olsen LR, Noerholm V, Abildgaard W. The sensitivity and specificity of the Major Depression Inventory, using the Present State Examination as the index of diagnostic validity. J Affect Disord 2001;66:159–64. 5. Ellervik C, Tybjærg-Hansen A, Nordestgaard BG. Total mortality by transferrin saturation levels: Two general population studies and a metaanalysis. Clin Chem 2011;57:459–66. 6. American Psychiatric Association. The diagnostic and statistical manual of mental disorders, fourth edition (DSM-IV). Washington D.C.: American Psychiatric Association; 1994. 7. World Health Organization. International statistical classification of diseases and related health problems, 10th revision (ICD-10). Diagnostic criteria for research. Geneva: World Health Organization; 1993. 8. Mokken RJ. Theory and practice of scale analysis. Berlin: Mouton; 1971. 9. Loevinger J. Objective tests as instruments of psychological theory. Psychol Rep 1957;3:635–94. 10. Molenaar IW, Debels P, Sijtsna K. User’s manual MSP, a program for Mokken scale analyses for polytomous items (version 3.0). Groeningen: ProGAMMA; 1994. 11. Grynderup MB, Mors O, Hansen AM, Andersen JH, Bonde JP, Kaergaard A, et al. A two-year follow-up study of risk of depression according to work-unit measures of psychological demands and decision latitude. Scand J Work Environ Health 2012;38:527–36. 12. Wing JK, Babor T, Brugha T, Burke J, Cooper JE, Giel R, et al. SCAN. Schedules for Clinical Assessment in Neuropsychiatry. Arch Gen Psychiatry 1990;47:589–93. 13. Alonso J, Angermeyer MC, Bernert S, Bruffaerts R, Brugha TS, Bryson H, et al. Prevalence of mental disorders in Europe: Results from the European Study of the Epidemiology of Mental
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19. 20. 21. 22. 23.
Disorders (ESEMeD) project. Acta Psychiatr Scand Suppl 2004;(420):21–7. World Health Organization. Composite International Diagnostic Interview (CIDI), core version 1.1. Geneva: WHO; 1993. Kringlen E, Torgersen S, Cramer V. A Norwegian psychiatric epidemiological study. Am J Psychiatry 2001;158:1091–8. Beck AT, Ward CH, Mendelson M, Mock J, Erbaugh J. An inventory for measuring depression. Arch Gen Psychiatry 1961;4:561–71. Kendell RE. The role of diagnosis in psychiatry. Oxford: Wiley-Blackwell; 1975. Konstantinidis A, Martiny K, Bech P, Kasper S. A comparison of the Major Depression Inventory (MDI) and the Beck Depression Inventory (BDI) in severely depressed patients. Int J Psychiatry Clin Pract 2011;15:56–61. Mechanic D. The concept of illness behavior. J Chronic Dis 1962;15:189–94. Bebbington PE, Tennant C, Hurry J. Adversity and the nature of psychiatric disorder in the community. J Affect Disord 1981;3: 345–66. Angst J. Treated versus untreated major depressive episodes. Psychopathology 1998;31:37–44. Danish National Board of Health. Reference program for unipolar depression in adults; 2007. http://www.sst.dk/publ/publ2007/plan/ sfr/sst_dep.rapport.pdf. Accessed 30 May 2013. Christensen KS, Sokolowski I, Olesen F. Case-finding and risk-group screening for depression in primary care. Scand J Prim Health Care 2011;29:80–4.
Christina Ellervik, M.D., Chief Physician, Department of Clinical Biochemistry, Naestved University Hospital, Copenhagen University Hospital, and Associate Professor, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. Jan Kvetny, M.D., Chief Physician, Department of Internal Medicine, Naestved University Hospital, Copenhagen University Hospital, and Professor of Endocrinology, Faculty of Health and Medical Sciences, University of Southern Denmark, Denmark. Kaj Sparle Christensen, M.D., Assistant Lecturer, Senior Researcher, Research Unit for General Practice, Institute of Public Health, Aarhus University, Aarhus, Denmark. Mogens Vestergaard, M.D., Professor, Research Unit for General Practice, Institute of Public Health, Aarhus University, Aarhus, Denmark. Per Bech, M.D., Professor of Psychiatry, Psychiatric Research Unit, Psychiatric Centre North Zealand, Copenhagen University Hospital, Denmark.
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Ellervik C, Kvetny J, Christensen KS, Vestergaard M, Bech P. Prevalence of depression, quality of life and antidepressant treatment in the Danish General Suburban Population Study. Nord J Psychiatry 2014;68:507–512. Background: The Danish General Suburban Population Study (GESUS), the objective of which is to facilitate epidemiological and genetic research, has included the Major Depression Inventory (MDI) and the WHO-Five Well-Being Index (WHO-5) among the medical health questionnaires. We were thus in a position to compare the 2-week prevalence of ICD-10 depression in the period from 2010 to 2012 with our previous Danish general population study from 2003, in which the MDI was also included. Aims: The aim of our analysis was not only to evaluate the point prevalence of ICD-10 depression but also to describe the prevalence of antidepressants received by the respondents in the GESUS study and the correspondence to their subjective well-being on the WHO-5 questionnaire. Methods: To evaluate the validity (scalability) of the MDI and the WHO-5 in the GESUS study we performed the non-parametric Mokken analysis. The scalability of the MDI and the WHO-5 was quite acceptable. Results: In total, 14,787 respondents were available from a response rate of 50%. The 2-week prevalence of ICD-10 depression was 2.3%, which is rather similar to the 2.8% in our 2003 study. The rate of people receiving antidepressants increased consistently with increasing severity of ICD-10 depression. Conclusion: This study has confirmed that the use of the MDI to obtain an ICD-10 depression diagnosis gives rather conservative estimates of the 2-week prevalence of depression in the Danish general population. The prescription of antidepressants depends on the severity of the ICD-10 depression diagnosis. • Depressive illness, Major Depression Inventory, WHO-5. Per Bech, M.D., Professor of Psychiatry, Psychiatric Research Unit, Psychiatric Centre North Zealand, Copenhagen University Hospital, Denmark, E-mail: [email protected]; Accepted 16 December 2013.
T
he aim of the Danish General Suburban Population Study (GESUS) is to facilitate epidemiological and genetic research using information from both selfadministrated questionnaires and from health examinations, biochemical measurements, genetic variants and nationwide registers for somatic disorders and mortality (1). The questionnaires contain items about medical conditions as well as mental health, e.g. the WHO-Five WellBeing scale (2, 3) and the Major Depression Inventory (MDI) (2, 4). In the analysis to be reported here, we have focussed on the WHO-5, the MDI and other depression-oriented items in the medical questionnaires (“Has your family doctor ever told you that you have suffered from depressive illness?” or “Do you currently receive antidepressant medication?”). The objective of our study has been to evaluate the point prevalence (past 2 weeks)
© 2014 Informa Healthcare
of ICD-10 depression, the lifetime prevalence of depressive illness, and the proportion of persons who were prescribed antidepressant medication during both the acute depression state and the long-term therapy of depressive illness. Finally, we used the WHO-5 results to compare the level of subjective quality of life in depressed and non-depressed persons.
Material and Methods GESUS was initiated in January 2010; enrolment is still ongoing. It is a cross-sectional study of the adult Danish suburban population in Naestved Municipality (approximately 70 km south of Copenhagen). The criteria for invitation are adults with a Danish citizenship who are resident in Denmark. All people aged 30 years and a DOI: 10.3109/08039488.2013.877074
C ELLERVIK ET AL.
randomly selected 25% of persons aged 20–30 years were invited by mail in numerical order, starting with citizens born on the 1st in every month and continuing. If individuals had not responded within 3 weeks of their scheduled attendance period, a reminder was sent with a new scheduled period. For the analysis to be reported here, we include participants from January 2010 to December 2012, from whom 50% of the contacted individuals responded. The study was approved by the appropriate institutional review boards and ethical committees (SJ-113, SJ-114), and reported to the Danish Data Protection Agency. Written informed consent was obtained from all participants. The investigation is in accordance with the principles of the Declaration of Helsinki. The GESUS study questionnaire can be viewed at www.p3gobservatory.org/catalogue.htm;jsessionid ACE6E593F10B80573 D64E965FA2DB3D8?measureId 38.
Self-administrated questionnaires The medical health questionnaire was similar to the one used for the Copenhagen City Heart Study (5). From this medical health questionnaire, we have especially focussed on the following items: •
•
Has your family doctor ever told you that you are suffering from or previously have suffered from depressive illness? If so, how old were you when the illness started? Do you currently take antidepressive medication?
The MDI is a self-administrated questionnaire covering the symptom criteria of clinical depression for both DSM-IV (6) and ICD-10 (7). The MDI has a double function as it can be used both as a diagnostic aid and as a measure of depression severity (4). The total score of the MDI ranges from 0 (no depression) to 50 (extreme depression). The ICD-10 algorithm for depression is used to categorise into mild (an MDI score of 21–25), moderate (an MDI score of 26–30) and severe categories (an MDI score of 31) (2). The WHO-5 questionnaire is a psychological wellbeing scale. Like the MDI, the time frame (window) is the previous 2 weeks. The WHO-5 includes the following items: being cheerful and in good spirits; being calm and relaxed; feeling active and vigorous; feeling fresh and rested when waking up in the morning; and having interest in the day-to-day activities. Each item is scored from 0 (at no time) to 5 (all of the time). The theoretical raw score range is consequently from 0 to 25. However, by multiplying the raw score by 4, the recommended score range goes from 0 worst imaginable quality of life to 100 best imaginable quality of life. In the general population surveys, the mean WHO-5 is approximately 70 (2). When screening for depression, a WHO-5 score 50 is used.
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Psychometric analysis The non-parametric Mokken analysis has been used to test the scalability of MDI and WHO-5 (2). The Mokken analysis (8) is based on Loevinger’s coefficient of homogeneity (9). We have used the program for polytomous items (10). According to Mokken (8), a coefficient of homogeneity between 0.30 and 0.39 is only just acceptable; a coefficient of homogeneity between 0.40 and 0.49 is acceptable for scalability.
Results Between January 2010 and December 2012, the GESUS consisted of 16,703 responders, but due to incomplete answers on the MDI, the WHO-5 or the items concerning lifetime depression or antidepressant medication, 14,787 responders were available for the analysis, 7971 females (54%) and 6816 males (46%). The mean age for all 14,787 persons was 53.5 13.3 years; for females 52.9 13.2 and for males 54.1 13.3. The coefficient of homogeneity by the Mokken analysis was 0.49 for the MDI and 0.64 for the WHO-5. In other words, both scales showed adequate measures of scalability (coefficient of homogeneity above 0.40). In total 1847 or 12.5% had been informed by their family doctor that they suffered from depressive illness [1259 (15.8%) females and 588 (8.6%) males]. In total 345 (2.3%) of the responders had, when using the ICD-10 algorithm for depression according to MDI, a current depression [223 (2.8%) females and 122 (1.8%) males]. Using the MDI summed total score, 376 or 2.5% had a current depression (261 or 3.3% females and 115 or 1.7% males) with a score of 26 or more. Table 1 shows that of the 1847 persons with a history of depressive illness according to the family doctor, 185 had a current ICD-10 diagnosis of depression (mild 64, moderate 67 and severe 54) according to the MDI, i.e. a 2-week prevalence of 10% of all persons with depressive illness. Table 1 shows the distribution of these 1847 persons according to their current ICD-10 depression diagnosis (none, mild, moderate and severe) in respect to WHO-5 and percentage of antidepressants. No statistically significant difference as regards the WHO-5 score or the proportion of persons in antidepressant treatment was found when females and males were compared. The mean WHO-5 score decreased significantly across the different ICD-10 depression categories (P 0.01) from no depression (60.4), mild (28.7), moderate (22.9) and severe (16.5). The percentage of persons receiving antidepressants increased significantly (P 0.01) from 36.9% among participants with a history of depression but no current ICD-10 depression to 68.5% among those with a severe ICD-10 depression. Table 2 shows the results for all 14,787 respondents regarding the current ICD-10 categories of no NORD J PSYCHIATRY·VOL 68 NO 7·2014
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Table 1. The WHO-Five Well-Being Index (WHO-5) scores [mean (standard deviation, s)] and the corresponding percentage of prescription of antidepressants in respondents with depressive illness. Current ICD-10 depression, according to MDI No current ICD-10 depression n 1662 Females, n 1132 Males, n 530 Mild ICD-10 depression n 64 Females, n 40 Males, n 24 Moderate ICD-10 depression n 67 Females, n 49 Males, n 18 Severe ICD-10 depression n 54 Females, n 38 Males, n 16
WHO-5, mean (s)
% Antidepressant
90 80
36.9% 38.4% 33.6%
60
28.7 (17.1) 28.6 (18.9) 28.8 (14.1)
51.6% 57.5% 41.7%
30
22.9 (13.0) 21.4 (10.8) 26.9 (17.3)
49.3% 44.9% 61.1%
16.5 (15.4) 18.3 (17.4) 12.3 (7.9)
68.5% 68.4% 68.8%
Females
50
Males
40
All
20 10
Table 2. The WHO-Five Well-Being Index (WHO-5) scores [mean (standard deviation, s)] and the corresponding percentage of prescription of antidepressants in the total group of respondents. WHO-5, mean (s)
% Antidepressant
0
None
Mild
Moderate
Severe
ICD-10 depression severity
Fig. 1. Mean WHO-Five Well-Being Index (WHO-5) scores within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the respondents with depressive illness (n 1847).
depression (24.5) and severe depression (16.0). The percentage of persons receiving antidepressants increased significantly (P 0.01) from no depression (4.7%), mild depression (22.3%), moderate depression (29.8%) and severe depression (50.0%). These results are graphically illustrated in Figs 1–4. When comparing Tables 1 and 2, it appears that patients with ICD-10 diagnoses of severe depression had consulted their family doctors in 54 out of 74 cases (73%). For moderate ICD-10 depression, this was 67 out of 144 cases (59%), whereas for mild ICD-10 depression it was 64 of 157 cases (41%). To explore this difference WHO-5 100 90
70.6 (17.1) 69.7 (17.5) 71.8 (16.5)
4.7% 6.1% 3.0%
30.0 (16.0) 30.1 (17.4) 30.0 (14.1)
22.3% 28.7% 14.3%
24.5 (12.7) 23.0 (11.1) 28.4 (15.6)
29.8% 27.7% 35.5%
80 70 60
Females
50
Males
40
All
30 20
16.0 (14.4) 17.1 (15.9) 13.1 (9.3)
MDI, Major Depression Inventory; s, standard deviation. All respondents, n 14,787. NORD J PSYCHIATRY·VOL 68 NO 7·2014
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60.4 (19.9) 59.8 (20.0) 61.6 (19.7)
(n 14,442), mild (n 157), moderate (n 114 and severe depression (n 74) in respect to WHO-5 and the proportion of persons in treatment with antidepressants. No statistically significant difference with regard to WHO-5 or percentage of antidepressants was found when females and males were compared. Across the different ICD-10 categories, the mean WHO-5 decreased significantly (P 0.01) from no depression (70.6), mild depression (30.0), moderate
No current ICD-10 depression n 14,442 Females, n 7748 Males, n 6694 Mild ICD-10 depression n 157 Females, n 87 Males, n 70 Moderate ICD-10 depression n 114 Females, n 83 Males, n 31 Severe ICD-10 depression n 74 Females, n 53 Males, n 21
WHO-5
70
MDI, Major Depression Inventory. Depressive illness, n 1847.
Current ICD-10 depression, according to MDI
DEPRESSION IN THE GESUS STUDY
50.0% 49.1% 52.4%
10 0 None
Mild
Moderate
Severe
ICD-10 depression severity
Fig. 2. Mean WHO-Five Well-Being Index (WHO-5) scores within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the total group of respondents (n 14,787).
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C ELLERVIK ET AL. Percent antidepressants
Percent antidepressants
100 90 80 70 60 50 40 30 20 10 0
100 90 80 70 Females Males All
60
Females
50
Males
40
All
30 20 10 None
Mild Moderate Severe ICD-10 depression severity
0 None
Fig. 3. The percentage of antidepressants received within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the respondents with depressive illness (n 1847).
between 73%, 59% and 41% for these patients who had consulted their family doctors, we performed an analysis (Table 3) in which age, gender and chronic medical conditions were taken into consideration. In connection with our question: “Has your family doctor ever told you that you have suffered from such medical conditions as cancer, stroke, diabetes etc.?” (Table 3), we used this hierarchy of these six conditions as listed in Table 3. If a person had more than one of the conditions, we only counted the condition with the highest ranking in the hierarchy. Thus, if a person answered yes to having both diabetes and iron deficiency, it was then diabetes that counted in Table 3. From Table 3 it can be seen that more females than males had contact with their family doctor in the moderate to severe depression group (P 0.02). For the chronic somatic conditions, the contact
Mild
Moderate
Severe
ICD-10 depression severity
Fig. 4. The percentage of antidepressants received within the three ICD-10 depression categories of severity (no, mild, moderate and severe) in the total group of respondents (n 14,787).
between patients and their family doctor were most frequent for severe depression (P 0.01). Table 4 shows the association between MDI summed total score and WHO-5 mean scores using all 14,787 observations. Table 5 shows a comparison with our previous general Danish population study with MDI (2). The 2-week prevalence of ICD-10 depression using the algorithm in MDI was 2.3% versus 2.8%, i.e. rather similar. When using the total MDI scores, the 2-week prevalence in the GESUS was only just lower than in the general population. The mean MDI score for each month was around 6.5 (6.6) through the 12 months (P 0.10)
Table 3. Age, gender and chronic medical conditions in depressed patients with and without contact with their family doctor. Severe ICD-10 depression (n 74) Contact (n 54) Age, mean (s) in years % Females Somatic conditions Cancer Stroke Diabetes Hyperthyroidism Angina pectoris Iron deficiency Total (number of patients) % Somatic condition
No contact (n 20)
Moderate ICD-10 depression (n 114) Contact (n 67)
51.7 (13.6) 52.2 (14.0) 50.8 (12.0) 70.4% 75.0% 73.1% 6 3 5 4 4 8 30 55.6%
1 0 0 1 0 1 3 15.0%
8 4 3 2 4 7 28 41.8%
No contact (n 47) 50.6 (15.3) 72.3% 4 0 2 0 3 4 13 27.7%
Mild ICD-10 depression (n 157) Contact (n 64)
No contact (n 93)
P
54.7 (13.1) 50.3 (13.5) 0.32 62.5% 50.1% 0.02 5 3 4 2 4 5 23 35.9%
8 1 5 2 2 6 24 25.8%
0.01
s, standard deviation.
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Table 4. A standardization of the Major Depression Inventory (MDI) using WHO-Five Well-Being Index (WHO-5) scores [mean (standard deviation, s)] as index. WHO-5 mean (s) MDI 0–9 MDI 10–14 MDI 15–20 (doubtful depression) MDI 21–25 (mild depression) MDI 26–30 (moderate depression) MDI 31–50 (severe depression)
86.8 (10.4) 59.7 (14.7) 48.0 (14.6) 40.7 (16.0) 33.2 (16.7) 28.3 (14.0)
s, standard deviation.
Discussion In this large population-based study of younger adults, the 2-week prevalence of ICD-10 depression was 2.3% (women: 2.8% versus men: 1.8%) and the proportion of persons with a history of depressive illness was 12.5% (women 15.8% versus men: 8.6%). The mean WHO-5 score decreased and the percentage of people receiving antidepressants increased consistently by increasing severity of the ICD-10 depression categories for both genders. The 2-week prevalence of the MDI based ICD-10 diagnosis of depression of 2.3% was rather similar to our previous general population study from 2003 (Table 4). It was also similar to the 3-month prevalence of the ICD-10 diagnosis of depression found by Grynderup et al. (11) who obtained a rate of 2.4% among Danish public employees when using the SCAN interview (12). The 12-month prevalence of DSM-IV major depression in six European countries (13) was 3.9% (with 5.0% for females and 1.9% for males). In this latter study, the Composite International Diagnostic Interview (CIDI) was used (14). However, in the Norwegian Kringlen et al. (15) study, the 12-month prevalence of DSM-III-R major depression was 7.3%. Self-rated depression scales such as the MDI or the Beck Depression Inventory (16) may eliminate many of the problems of inter-rater reliability Table 5. A comparison between the present study (GESUS) and our previous general Danish population study carried out in 2003. GESUS, n 14,787 Responder rate Age, years mean (s) Females Males % females Coefficient of homogeneity ICD-10 depression MDI 20 MDI 25
General Danish population study from 2003 (ref. 2), n 1867
50% 52.9 (13.2) 54.1 (13.3) 53.9% 0.49 2.3% 4.8% 2.5%
(17). The MDI coefficient of homogeneity (Table 4) showed a good scalability, indicating an acceptable response pattern in our MDI studies; this is also to be found in the study by Konstantinidis et al. (18). Our results as to the prevalence of ICD-10 depression according to the MDI algorithm, as well as the summed MDI raw score, are very similar to our general Danish population study from 2003 (Table 4). With regard to the lifetime prevalence of depressive illness, our rates of 15.8% for females and 8.6% for males were rather similar to those in the Alonso et al. (13) study, which obtained a lifetime prevalence of 16.5% for females and 8.9% for males. The study by Kringlen et al. (15) showed higher lifetimes rates, namely approximately 24% for females and 10% for males, i.e. especially for females. However, in all these studies, females had a higher lifetime prevalence of depression than males. The great majority of patients with a current, severe ICD-10 diagnosis of depression had consulted their family doctors in 73% of the cases. Our socio-demographic analysis seems to support Mechanic’s original observation (19) that patients with chronic medical conditions are more likely than other persons to seek help from their family doctors when under social adversity. As discussed by Bebbington et al. (20), this illness behaviour is especially in operation if the help-seeking persons have no expectation of any termination of their social adversity. Using the WHO-5 as a measure of positive wellbeing, we could demonstrate that for people with a current depressive episode, the WHO-5 sum score was significant lower among persons on antidepressant medication than in those not receiving antidepressants. This is in agreement with the study by Angst (21), who found in a general population study in Zürich that persons consulting their family doctor with depression are more ill than those not consulting their family doctor when depressed. In summary, the MDI demonstrated conservative prevalence estimates of ICD-10 depression in a large Danish general population sample, thus supporting its use for diagnostic evaluation of depression, as recommended by the Danish National Board of Health (22). Further studies are needed to evaluate the optimal administration procedure and validity of the MDI in primary care settings (23).
68% 53.1 (16.4) 55.9 (16.3) 52.9% 0.47 2.8% 6.2% 3.7%
s, standard deviation; MDI, Major Depression Inventory. NORD J PSYCHIATRY·VOL 68 NO 7·2014
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Acknowledgements—The GESUS study received support from Johan and Lise Boserup Foundation; TrygFonden; Det Kommunale Momsfond; Johannes Fog’s Foundation; Region Zealand; Region Zealand Foundation; Naestved Hospital; Naestved Hospital Foundation; the National Board of Health; Danish Agency for Science, Technology and Innovation.
Disclosure of interest: Kaj Sparle Christensen and Mogens Vestergaard are supported in part by an unrestricted grant
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from the Lundbeck Foundation. Christina Ellervik, Jan Kvetny and Per Bech have none to disclose.
14. 15.
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Disorders (ESEMeD) project. Acta Psychiatr Scand Suppl 2004;(420):21–7. World Health Organization. Composite International Diagnostic Interview (CIDI), core version 1.1. Geneva: WHO; 1993. Kringlen E, Torgersen S, Cramer V. A Norwegian psychiatric epidemiological study. Am J Psychiatry 2001;158:1091–8. Beck AT, Ward CH, Mendelson M, Mock J, Erbaugh J. An inventory for measuring depression. Arch Gen Psychiatry 1961;4:561–71. Kendell RE. The role of diagnosis in psychiatry. Oxford: Wiley-Blackwell; 1975. Konstantinidis A, Martiny K, Bech P, Kasper S. A comparison of the Major Depression Inventory (MDI) and the Beck Depression Inventory (BDI) in severely depressed patients. Int J Psychiatry Clin Pract 2011;15:56–61. Mechanic D. The concept of illness behavior. J Chronic Dis 1962;15:189–94. Bebbington PE, Tennant C, Hurry J. Adversity and the nature of psychiatric disorder in the community. J Affect Disord 1981;3: 345–66. Angst J. Treated versus untreated major depressive episodes. Psychopathology 1998;31:37–44. Danish National Board of Health. Reference program for unipolar depression in adults; 2007. http://www.sst.dk/publ/publ2007/plan/ sfr/sst_dep.rapport.pdf. Accessed 30 May 2013. Christensen KS, Sokolowski I, Olesen F. Case-finding and risk-group screening for depression in primary care. Scand J Prim Health Care 2011;29:80–4.
Christina Ellervik, M.D., Chief Physician, Department of Clinical Biochemistry, Naestved University Hospital, Copenhagen University Hospital, and Associate Professor, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. Jan Kvetny, M.D., Chief Physician, Department of Internal Medicine, Naestved University Hospital, Copenhagen University Hospital, and Professor of Endocrinology, Faculty of Health and Medical Sciences, University of Southern Denmark, Denmark. Kaj Sparle Christensen, M.D., Assistant Lecturer, Senior Researcher, Research Unit for General Practice, Institute of Public Health, Aarhus University, Aarhus, Denmark. Mogens Vestergaard, M.D., Professor, Research Unit for General Practice, Institute of Public Health, Aarhus University, Aarhus, Denmark. Per Bech, M.D., Professor of Psychiatry, Psychiatric Research Unit, Psychiatric Centre North Zealand, Copenhagen University Hospital, Denmark.
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