Preliminary report of a study on the prevalence of bipolar disorders among Chinese adult patients seen in Hong Kong's primary care clinics suffering from depressive illness

Mary BL Kwong鄺碧綠, Ki-yan Mak麥基恩, Billy SO Law羅世安, Shiu-kow Sham岑紹裘

HK Pract 2009;31:168-175

Summary

Objective: To assess the prevalence of bipolar disorders among Chinese adult patients, who were suffering from depression, and were seen in Hong Kong's primary care clinics.

Design: By questionnaire survey.

Subjects: 215 Chinese adult depressive patients were recruited from 10 primary care clinics in Hong Kong from October 2008 to April 2009.

Main outcome measures: Screening for bipolar disorders was performed using the Mood Disorder Questionnaire (MDQ) and Hypomanic Check List - 32 (HCL-32). Patients self-reported their own demographics and family history. The primary care doctors assessed patients for depression symptoms using the Diagnostic and Statistical Manual of Mental Disorder ?Fourth Edition (DSM-IV) and recorded their medical history, co-morbid health status and medication used.

Results: Of the 215 patients enrolled, 20.9% were found positive for bipolar disorder on the MDQ.

Conclusion: The prevalence of bipolar disorders among Chinese adult patients suffering from depression in Hong Kong's private primary care clinics was 20.9% by MDQ screening. Our result was comparable to other studies.

Keywords: Depression, bipolar disorders, Chinese adult, primary care, screening

摘要

目的：評估在香港基層醫療，華籍抑鬱症成年病人的躁鬱症患病率。

設計：社區私營診所的基層醫生按次序選取抑鬱症病人，邀請他們完成心境障礙問卷（MDQ）和輕躁症狀自評量表32（HCL-32），並加以分析。

研究對象：2008年10月至2009年4月期間，在香港10間基層診所的215位華籍抑鬱症成年病人。

主要測量內容：以心境障礙問卷（MDQ）和輕躁症狀自評量表（HCL-32）篩選躁鬱症病人。病人自述其個人資料和家族病史。基層醫生按DSMIV、醫療記錄、共存疾病狀況和藥物應用來評估抑鬱症病徵。

結果：在參與研究的215位病人，20.9%經MDQ篩選後被評估為患上躁鬱症。

結論：以MDQ評估在香港基層醫療中，華籍抑鬱症成年病人的躁鬱症患病率為20.9%，與其他研究結果相若。

主要詞彙：抑鬱症，躁鬱症，華籍成年人，基層醫療，篩選。

Introduction

The World Health Organization Health Report 2001 stated: Major depression is now the leading cause of disability globally and ranks fourth in the ten leading causes of the global burden of disease... depression... the second cause of the global disease burden.? Depression is the commonest mood disorder seen in general practice. The main reasons for this setting are convenience, well established rapport with the family doctors and avoidance of stigmatization.^2,3

Bipolar depression is often underdiagnosed or misdiagnosed as (unipolar) depression. Most patients with bipolar disorder seek treatment for depression, and not for mania or hypomania.⁴ Therefore clinicians often miss the diagnosis of bipolar (spectrum) disorder. A large number (up to 60%) of refractory depressive patients are found to have a bipolar diathesis.⁵ One third of bipolar patients required 8 to 10 years from illness onset until eventually diagnosed with bipolar disorder.^6-8 The most common incorrect diagnosis (69%) is depression.⁸

The course of bipolar patients will worsen if mistreated with anti-depressant medication. Anti-depressant-induced mania was studied by Boerlin.⁹ Induction of manic phase and rapid cycling (55%) and acceleration of rapid cycling (23%) were shown by Ghaemi et al ^10,11 Therefore, arriving at the correct diagnosis is important to avoid inappropriate treatment. This lack of correct diagnosis of bipolar disorder in the primary care setting has been under recognized.¹²

Manning et al reported 26% of patients with depression in a family practice were having bipolar disorder.¹³ 21.3% of patients were reported by Hirschfeld et al in a general out-patient family medicine clinic at the University of Texas.¹⁴ In France, Hantouche et al showed that the rate of bipolar disorder in a population of patients presenting with a major depressive episode was 28%.¹⁵ Benazzi in Italy found that 49% of out-patients presenting with depression had bipolar II disorder.¹⁶ However, there is no local data published on the prevalence of bipolar disorders among Chinese adult patients suffering from depression in primary care in Hong Kong.

Epidemiological study had followed-up patients hospitalized for major depressive disorder for over 20 years. A diagnostic change from depression to bipolar I disorders occurred in about 1% of the patients per year and to bipolar II disorders in about 0.5% per year. Therefore, the risk of depression disorders developing into bipolar disorders remains constant for lifelong.¹⁷

Objective

The primary objective of this study was to assess the prevalence of bipolar disorders among all depressive patients seen in Hong Kong primary care.

Lacking of awareness and understanding of bipolar affective disorders prevents a correct diagnosis from being made earlier, mistreatment of the correct disorder worsen its course, and have negative impact on patients and families and on society.

Our aim is to raise primary care doctors?awareness of bipolar disorders, especially bipolar II with mild hypomania which has been found to be under-diagnosed or treated inappropriately as depression in overseas?primary care studies. We wish to bring to mind of our doctors ?always assess for manic and hypomanic symptoms (ongoing and periodically) in patients with depression in order to avoid missing a diagnosis of bipolar affective disorders.

Method

Doctors selection

Only primary care doctors from the private and public sectors who consented to provide data of their patients suffering from depression were invited. Participating doctors were each provided with a Doctors Code according to the 18 districts in the Hong Kong Special Administrative region, namely Central & Western, Wan Chai, Eastern, Southern, Yau Tsim Mong, Sham Shui Po, Kowloon City, Wong Tai Sin, Kwun Tong, Tsuen Wan, Tuen Mun, Yuen Long, North, Tai Po, Sai Kung, Sha Tin, Kwai Tsing, Islands in order to keep their names anonymous and confidential.

However, up to April, 2009, only data from private doctors were available for analysis.

Patient selection

All patients aged 18-65 years with a past or current diagnosis of depression irrespective of their response to anti-depressant treatment were included. A diagnosis of depression was confirmed if patients fulfilled the Diagnostic and Statistical Manual of Mental Disorders ?Fourth Edition (DSM-IV) criteria for depression on history taking by the doctor. Patients were only recruited if they consented to enter the study. Patients were excluded if they had psychotic disorders or organic brain syndrome.

Patients who were under treatment for other co-existing chronic illnesses, were however not excluded but their participation were clearly stated in another data collection sheet and their co-existing conditions were kept for further analysis as co-morbidities.

All participating patients were asked to sign a written consent form after being fully explained about the study. They would complete two questionnaires and gave their socio-demographic data which covered their sex, age, marital status, occupation, educational achievement, family history of psychiatric problems, and co-morbid health status. Those illiterate were given help by a helper to complete the forms.

The reception nurse would explain to them and witnessed their signing their signature on the consent form.

Questionnaire selection

Measurement tools used in this study were:

DSM IV was used for diagnosis of major and minor depression. This was completed by the doctors for diagnosing depression in their patients. It consists of 9 criteria with either item No. 1 or No. 2 as must be present items.

Item No. 1 depressed mood Or
Item No. 2 significant loss of interest or pleasure And
Item No. 3 significant weight loss when not dieting; or weight gain
Item No. 4 insomnia; or hypersomnia
Item No. 5 psychomotor agitation; or retardation
Item No. 6 fatigue or loss of energy
Item No. 7 feeling of worthlessness; or excessive or inappropriate guilt
Item No. 8 diminished ability to think or concentrate, or indecisiveness
Item No. 9 suicidal ideation.

Total positive score of 5 out of 9 criteria for major depressive disorder (MDD) and 3 out of 9 criteria for minor depression. The doctor should stress on the 2 weeks duration and the symptoms existing nearly every day.

Hypomania Checklist ?32 (HCL-32) had questions to be completed by the patient. It is a sensitive instrument for detecting hypomanic symptoms. Those scored 14 or above are considered as positive. (See Appendix 1)

Mood disorder questionnaire (MDQ) had 13 questions to be completed by the patient. Positive MDQ screening is defined as 7 out of 13 questions asking about mood and behaviour that are typically associated with mania. (See Appendix 2)

Results and analysis

During the period of study from October 2008 to April 2009, 218 patients with depression were identified. Three patients were excluded because they were aged older than 65 years old. Therefore 215 patients with depression were recruited. The youngest was 20 years old.

The ages of the recruited patients ranged from 20 to 65 years old. The male to female ratio was 1:2, which was about the same across all age groups.

Overall, we had 45 (20.9%) out of 215 patients who scored more than 7 in the MDQ screening test showing there was a prevalence of about one in 5 cases of depressed patients tested positive for having bipolar disorder.

In a further analysis of our depressed patients, there were 182 cases of major depression and 33 cases of minor depression. Only 1 male patient had MDQ scoring greater than 7 in the minor depression group. 44 out of 182 (24.2%) patients with major depression and 1 (3%) out of 33 patients with minor depression were tested positive for having mania disorder.

Therefore, in our study group, the prevalence rate for bipolar disorders among our depressed patients was 20.9% (45); 24.2% (44) in the major depression group and 3% (1) in the minor depression group.

Using Chi-square analysis, there were no statistical difference between bipolar disorder and major depression disorder groups with respect to age and sex.

Discussions

Bipolar disorder, known by its older name "anic-depressive illness" first appeared in literature in 1958. It is a severely disabling medical condition and ranks the sixth cause of disability in the world, according to the World Health Organization.²¹ However, with appropriate medical treatment and psychotherapy, many individuals with bipolar disorder can live full and satisfying lives with periods of normal or near normal functioning between episodes. Early diagnosis and treatment of bipolar disorder can also reduce the risk of complications, which may include suicide, alcohol or drug abuse, relationship, work, and/or school problems.^22-24

MDQ was first described by Hirschfeld et al in 2000.²⁰ Sensitivity 0.58 (0.454 to 0.706, 65% CI) and specificity 0.93 (0.878 to 0.981 CI) were verified by Hirschfeld et al in 2005.¹⁴ Validation by Wong & Chung, Department of Psychiatry, The University of Hong Kong in 2008, using Structured Clinical Interview showed a similar high specificity of 0.89.²⁵ Such a high specificity means that patients who scored 7 or more by this test are likely bipolar patients. MDQ appears thus a reliable test for diagnosing depressed patients for presence of bipolar disorders.

The prevalence of bipolar disorders among all depressive patients seen in our study was 20.9%. It means that 1 in 5 of all depression patients we were seeing may be suffering from bipolar disorder. This is comparable to the 21.3% described in the Hirschfeld study.¹⁴

In the major depression group, the prevalence of 24.2% means that there was a 1 in 4 chance of missing a bipolar spectrum disorder in patients with major depression. We must be very careful and pay attention to the elated symptoms and use of antidepressant medication in these patients.

The prevalence of bipolar disorders amongst those with minor depression was only 3%. The choice whether to screen for bipolar disorders in this subgroup of patients is difficult to make. Nevertheless, doctors have the duty to provide beneficence for their patients, and so doctors seeing such patients must balance this need depending on the clinical situation.

Angst's study in 2005 distinguished bipolar affective disorder from major depressive disorder using the hypomania checklist's 32 questions and found it has a sensitivity of 80% and a specificity of 51%.25 Similarly, the HCL-32 was validated among Chinese patients in Taiwan by Wu et al in 2008 with a sensitivity of 82% and a specificity of 67%.²⁶ This means that the HCL-32 is very sensitive with low false negative results. However, it may have high false positive findings.

The prevalence of bipolar disorders in our study according to the HCL-32 test was 54% (117/215). It appears that the HCL-32 was too sensitive for detecting bipolar affective disorders among those already diagnosed with depression. Perhaps the test is more useful for screening for bipolar disorder among non-psychiatric patient as shown by the survey performed by Mak et al, where the prevalence among primary care general population in Hong Kong was around 3.5%.²⁷

Results from this study did not show any significant statistical difference in gender among those with bipolar disorder and major depression disorder, which w as different from previous studies where there was a male predominance.²⁸

In our study, 40 ?50 years old was the peak age range for Chinese patients seeking depression treatment. This may be, because in the Chinese culture, our adults patients tend to seek treatment late, or wait until treatment is really needed, or when their unhappy life events have accumulated to a bursting point.

Our studies are similar to others in that more female patients seek medical treatment for depression.²⁹ It is possible that men are more resistant in developing depression. Perhaps it is because of a global culture that men are less willing to seek help. Therefore primary care doctors should be more alert when dealing with male depression. More studies on men's health should be encouraged.³⁰

Limitation

Our study has a small sample size (215 cases). Our data was collected in a non-blinded fashion. Doctors may have invited or were able to identify more patients with major depression (182 cases are MDD and 33 cases are Minor Depression) to join the study.

All the patients were from the private sector and this may have had a sampling bias. This may not reflect the whole picture in the community. We are still waiting for approval from Department of Health and Hospital Authority to use their patients?data.

Although HCL-32 is a sensitive instrument and MDQ has high specificity, they do not distinguish between bipolar-I and bipolar-II disorders.

This paper is only the preliminary report of our study. More primary care doctors will be recruited to join our study, with a planned patient recruitment number of 1000.

Conclusion

Prevalence for bipolar disorder were found to be 20.9% in all depression patients, 24.2% in major depression group, 3% in minor depression group in this preliminary screening of adult patients with depression in private general practice using the MDQ.

We can be more aware of bipolar disorder and always assess for manic and hypomanic symptoms (on-going and periodically) in managing patients with depression in the primary care setting.

Acknowledgements

I wish to thank the following participating doctors: Chan Kit Chi, Cheung Ying Man, Chan Ming Wai, Kwong Bi Lok, Law Sai On, Lam Wing Wo, Lee Fook Kay, Tam Chi Wing, Sham Shiu Kow, Yeung To Ling, for their cases contribution and SABAD (The Society for the Advancement of Bipolar Affective Disorder) for Research Funding.

Key messages

1. Depression is the most common mood disorder seen in general practice and ranks fourth in the ten leading causes of the global burden of disease.
2. Bipolar depression is often misdiagnosed as unipolar depression; mistreated with antidepressant will induce manic phase and rapid cycling.
3. Prevalence of bipolar disorder was found to be 20.9% in all depression group and 24.2% in major depression group in this preliminary report.
4. It is always worthwhile to assess for manic and hypomanic symptoms (on-going periodically), in managing depressive patient in the primary care setting.