East Asian Arch Psychiatry 2011;21:22-7


Referral Patterns and Clinical Characteristics of Subjects Referred to Substance Abuse Clinic of a Regional Hospital in Hong Kong
A Tang, HJ Liang, GS Ungvari, WK Tang

Dr Alan Tang, MBBS, FHKAM (Psychiatry), Department of Psychiatry, Prince of Wales Hospital, Hong Kong SAR, China.
Dr HJ Liang, MPhil, Department of Psychiatry, The Chinese University of  Hong Kong, Hong Kong SAR, China.
Prof GS Ungvari, MD, PhD, The University of Notre Dame Australia / Marian Centre, Perth, Australia.
Dr Wai-kwong Tang, MBChB, MD, FHKAM (Psychiatry), Department of Psychiatry, The Chinese University of Hong Kong, Hong Kong SAR, China.

Address for correspondence: Dr Wai-kwong Tang, Department of Psychiatry,
7th Floor, Shatin Hospital, 33 A Kung Kok Street, Ma On Shan, New Territories, Hong Kong SAR, China.
Tel: (852) 2636 7754; Email: tangwk@cuhk.edu.hk

Submitted: 5 August 2010; Accepted: 21 September 2010

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Objectives: To examine the clinical characteristics of subjects referred to the Substance Abuse Clinic of the Prince of Wales Hospital between 1 January 2007 and 31 December 2009 in Hong Kong.

Methods: A chart review of 131 subjects referred to the Substance Abuse Clinic during the study period was carried out. Psychiatric diagnoses were made by a psychiatrist, according to the 10th edition of the International Classification of Diseases.

Results: Social workers were increasingly a main source of referrals, accounting for 34% of referrals during the entire study period (and 43% in 2009). Another important referral source was the Hospital Authority system in Hong Kong, which accounted for 38% of referrals over the 3-year study period. Ketamine, methamphetamine, and cough mixtures were the most common drugs of primary misuse, the proportion of users being 34%, 24% and 12%, respectively. In these referals, the most common psychiatric diagnosis was substance-induced psychotic disorder, followed by depressive disorder, made in 44% and 22% of the subjects, respectively.

Conclusions: Among Hong Kong substance abusers, psychotic and depressive disorders are common, and ketamine is the most commonly misused drug.

Key words: Comorbidity; Referral and consultation; Substance-related disorders


目的:检视2007年1月1日至2009年12月31日期间转诊至香港威尔斯亲王医院药物滥用门诊患 者的临床特徵。

方法:查阅研究期间131名转诊患者的病历记录。精神科专家根据国际疾病分类第10版为患者 确诊精神疾病。

结果:在这3年研究期内,社工是主要转诊来源,研究期间平均占总体34%,2009年则占 43%。医院管理局是转诊的另一主要来源,占38%。氯胺酮、安非他命和止咳合剂是头3种最 常见的滥用药物,分别占34%、24%和12%。最常见的精神科诊断为药物诱发型精神病(44%) 和抑郁症(22%)。




The Prince of Wales Hospital (PWH) is the main medical facility serving the Northeast area of the New Territories in Hong Kong. It has a catchment population of 1.2 million, which is about one-sixth that of the entire special administrative region.1 Patients considered to be drug abusers and suspected of having mental disorders are referred to the PWH Substance Abuse Clinic (SAC). A change in the pattern of drug abuse in Hong Kong has been observed in recent years. There has been a gradual increase in the use of psychotropic drugs and a simultaneous decline in the use of opiates, particularly among the younger persons. According to the Central Registry of Drug Abuse (CRDA) of the Narcotics Division, Security Bureau, the recent decline in heroin use has been accompanied by a corresponding increase in psychotropic drug use.2 Among drug abusers aged under 21 years, 99% reported psychotropic drug use, while only about 2% reporting heroin use.3 The literature contains ample evidence of an association between psychotropic drug abuse, psychosis, and major mood disorders.4,5 Studies involving adolescents have generally yielded a high rate of co-morbid mental health problems,6 as have studies in adults, in the United States more than 60% of such drug abusers reported depression, anxiety or traumatic distress.7,8

No data are available on psychiatric co-morbidity rates among drug abusers in Hong Kong. The objective of the current study was to describe the demographics, clinical characteristics, referral patterns, and psychiatric co- morbidities of drug abusers in Hong Kong.


Study Population

This retrospective chart review covers the 36-month period from 1 January 2007 to 31 December 2009. All new patients seen at the PWH SAC during this period were included in the study. The SAC accepts referrals of patients aged 12 years or above, but not those suffering from alcohol- related disorders or on conditional discharge (as defined in Section 42B of the Mental Health Ordinance). The other precondition for SAC acceptance was active substance abuse within the previous 12 months.

The study protocol was approved by the Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee.

Data Collection

When a patient first attended the clinic, his or her source of referral, age, gender, level of education, marital status, district of residence, occupation, type of drugs misused, co-morbid psychiatric diagnosis, and previous treatment were recorded on a standard form. All patients were diagnosed according to the 10th edition of the International Classification of Diseases.9

Statistical Analysis

The data were analysed using the Statistical Package for the Social Sciences, Windows version 15.0. Patients’ socio- demographic characteristics, types of drugs misuse, and co-morbid psychiatric diagnoses were calculated using descriptive statistics.


Socio-demographic Characteristics, Referral and Drug Abuse Patterns

The socio-demographic characteristics of the sample and the referral patterns are shown in Table 1. With the establishment of 2 Counselling Centres for Psychotropic Substance Abusers in the region studied, referrals from social workers increased to 43% in 2009, rendering them the main source of referral. The frequencies of both primary and secondary drug abuse, as well as the total frequency of drug abuse, are shown in the Figure. In addition to their primary drug abuse, 100 (76%) of the subjects reported regular use of a second substance, whilst 26% of these subjects reported regular use of 3 or more drugs.

Co-morbid Psychiatric Disorders and Treatment at First Attendance

The distribution of suspected psychiatric disorders and psychiatric diagnoses are presented in Table 2. Four patients underwent immediate hospitalisation at their first attendance; 1 had a typical manic episode with psychotic symptoms, 1 exhibited a delusion of infestation, and the other 2 were depressed and posed a substantial suicidal risk. Nearly three quarters of the subjects (n = 95, 73%) received counselling on the harmful effects of drug abuse, primarily from the clinic nurse. Only 1 patient was referred to a clinical psychologist.

In all, about 70% (n = 91) of the patients received some form of pharmacotherapy on their first visit. Of these, 48% (n = 44) were treated with antipsychotics, 43% (n = 39) with antidepressants, 33% (n = 30) with hypnotics / anxiolytics, and 3% (n = 3) with mood stabilisers. For a variety of reasons, referral to a social worker was deemed necessary for 31% (n = 40) of the subjects, which included: counselling about illicit substance use, housing or other welfare issues, and dealing with family / relationship problems, and rarely because of unemployment. Only 6 (5%) of the subjects accepted referrals to a residential detoxification centre at their first attendance.


Characteristics of Drug Abuse and Referral Patterns

Patients younger than 30 years accounted for 57% of the sample in this series, compared to 49% in CRDA statistics. The presence of a greater proportion of younger patients may explain why a greater proportion of our subjects had attained certain educational standards than that reported in CRDA statistics (44% vs. 35%). As in the CRDA data,10 single, unemployed, or men with low skills constituted the majority of the study sample.

In the current study, ketamine topped the list of substances abused in Hong Kong, followed by methylamphetamine (“ice” in local slang). Growth in the popularity of ketamine over the past decade has been facilitated by declining prices and increased availability, and it is now the most frequently abused psychoactive drug in Hong Kong. Zopiclone and 3,4-methylenedioxymetham- phetamine (MDMA) are similarly popular, although they are mainly abused as secondary drugs. Affordability and easy availability of zopiclone have contributed to its popularity. The high price of MDMA (around HK$100 per tablet) and the rapid development of tolerance11 have probably deterred many from its regular use, though it remained a quite popular secondary drug of choice among the subjects in this study.

Cough mixtures are the third most popular primary drug of abuse in the SAC, but appear less frequently on the secondary drug list. Benzodiazepines, cocaine and cannabis are less frequently abused as primary drugs, but quite often as the secondary agents. Cocaine is far more expensive than most other substances, and is thus unaffordable for regular use. However, in Hong Kong its popularity has increased over the last decade owing to a falling price and increasing availability,12 both due to the large supplies of crack cocaine from South America.13 This trend is likely to continue, as the amount of cocaine seized in the first 10 months of 2009 surged to 112 kg (an increase of 90% over 2008).14 In this study, opiate and solvent abuse had become relatively rare. In general, the pattern of drug abuse identified in this series of subjects is very close to that of the overall situation in Hong Kong reported elsewhere.15

The subjects in this study were primarily referred by social workers, with local youth outreach teams and drug treatment / counselling centres that have now become the key reporting resources in Hong Kong.15 Another significant source was the Hong Kong Hospital Authority, as unsurprising substance abuse is often a co-morbidity of physical diseases.16 Careful screening and the early referral of substance abusers by such general health services facilitates early treatment. For which reason, several studies have explored methods of improving the recognition and referral of substance abusers reaching general medical facilities.17

Compared to this study, patients in another SAC in Hong Kong (Tuen Mun Substance Abuse Clinic [TMSAC]) were more likely to abuse heroin (23%) and were referred by mental health services (34%) and general medical care systems (28%). Other than heroin, ketamine (22%), cough medicine (22%) and methylamphetamine abuse (13%) were also common, of which the pattern was similar to ours.18 Moreover, subjects in the current study were of younger age, had higher levels of education, and relatively fewer were single, unemployed, or had criminal records.

Psychiatric Morbidity and Treatment

Few studies have surveyed the characteristics of substance abuse patients referred to mental health services. The most frequent diagnoses in this study were substance- induced psychosis and depressive disorder, either suspected at referral or established at intake to the SAC. Other diagnoses included schizophrenia, panic disorder, obsessive-compulsive disorder, adjustment disorder, and eating disorder. This result is similar to above-mentioned TMSAC latest annual report18 that of 68 patients, 32 had substance-induced psychosis and 12 had depressive disorder. This psychiatric co-morbidity pattern differed from those reported in large-scale epidemiological studies, in which alcohol abuse and mood and anxiety disorders were the most commonly reported substance abuse comorbidities.16,19,20 It was expected that the substance abuse patients referred to our psychiatric service would have a more severe psychopathology than their counterparts in the community. Similar to the co-morbidity patterns reported here, Havassy et al21 found more schizophrenia spectrum disorders in substance abusers treated in the mental health system than in those treated in addiction facilities (43% vs. 36%).21 A major difference between our study and Havassy et al’s is that 63% of their sample abused alcohol,21 whereas there was no alcohol abuse in our study. Alcohol abuse is closely related to anxiety and depressive disorders,21 which explains the considerably greater co-morbidity of these disorders (36% vs. 22% for depression, and 57% vs. 6% for anxiety disorders) in Havassy et al’s sample21 relative to ours.

Ketamine was found to be the most frequently abused drug in the current study, which is in line with local reports.The relationship between ketamine and psychosis and mood disorders has been extensively investigated, with its use linked to a high score on the Brief Psychiatric Rating Scale (BPRS) in both healthy volunteers22-24 and schizophrenia patients23,24 under the experimental conditions. The elevated BPRS scores returned to normal within minutes of the termination of ketamine infusion, consequently indicating that the drug has a reversible effect.25 However, the effect of long-term ketamine use remains unknown. A well-known case is that of John Lilly, the American physician and self- styled ‘psychonaut’ who took ketamine for decades. He once became convinced that he was “a visitor from the year 3001”26 and phoned the White House to warn then- President Gerald Ford about “a danger to the human race involving atomic energy and computers.”27 Although Lilly did not suffer from a prolonged psychosis, he had repeated psychiatric hospitalisations, possibly as a result of ketamine abuse.

Elation is observed when ketamine is given to both detoxified alcoholics28 and healthy volunteers.26,29,30 There is also preliminary evidence to suggest that ketamine may have some benefits for patients with treatment- resistant depression,31-34 hence paving the way for the development of antidepressants that target the glutamate system.35 Notwithstanding, whether the chronic intake of large doses of ketamine is related to depressive disorders remains unknown, it should be noted that a large proportion of ketamine users also take other stimulants such as methylamphetamine and cocaine, both of which are associated with depressive disorders.


This study has 4 limitations. First, the small sample size restricted separate analysis of the outcomes for each substance and its association with co-morbid psychiatric disorders. Second, the outcomes were judged by clinical impression without the use of any standardised rating instrument. Third, this study used case notes reviewing design which may cause the lack of detail about subject’s condition. Time frame and frequency of drug abuse, as important severity index of drug abuse and details of referral process, were not recorded in this study. Fourth, samples of this study were only recruited from SAC of PWH which might limit the generalisation of results to other SACs in Hong Kong.


An increasing number of patients have been referred to the PWH SAC in the past few years. Social workers had become the main source of these referrals by 2009. During the study period, the most common psychiatric disorders encountered at the SAC were substance-induced psychotic disorder (44%) and depressive disorder (22%), and the most frequently abused drugs were ketamine (34%) and methylamphetamine (24%). Most of the subjects referred to the SAC received pharmacotherapy and drug counselling. Antipsychotics and antidepressants were the most common drugs prescribed, corresponding to the aforementioned most frequent co-morbid diagnoses. Patients with serious family problems or other psychosocial issues were referred to social workers, but rarely to clinical psychologists. Further studies should compare the interventions, clinical outcomes and abstinence rates in different co-morbid psychiatric disorders in a larger sample.


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