The Patient Health Questionnaire-9 for measuring depressive symptoms among the general population in Hong Kong
Introduction
Depression is one of the most prevalent mental disorders in primary care [1], [2]. The Patient Health Questionnaire-9 (PHQ-9) is an efficient and reliable self-report instrument [3]. Consisting of 9 items, this scale is brief and convenient to administer in epidemiological studies. The items (eg, feeling down, depressed, and hopeless) were selected to map on the criteria for the diagnosis of major depressive disorder (MDD) in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Accumulating evidence showed that the PHQ-9 has comparable sensitivity and specificity to many other depression measures (eg, Hospital Anxiety and Depression Scale) [4]. This scale has been increasingly used across the general population and patient groups (eg, patients with stroke, brain injury, and HIV) in the community and clinical settings. A meta-analysis on the application of the PHQ-9 in 17 validation studies concluded that the PHQ-9 is acceptable, is as good as longer clinician-administered instruments in different countries and populations, and has been widely used in a variety of setting such as primary care, specialist medical services (eg, cardiology, dermatology, and head injury), and community samples [4], [5], [6]. In addition, a recent systematic review concluded that the PHQ-9 is a valid and efficient measurement for identifying, differentiating, and monitoring depressive disorders [7].
The PHQ-9 has been translated into different languages, including Portuguese [8], Spanish [9], French [10], Thai [11], and Korean [12]. The Chinese version of the PHQ-9 has been used among Chinese Americans [13], [14], [15]. A validation study among 364 elderly individuals in primary care in mainland China demonstrated good psychometric properties [16]. However, the psychometric characteristics of the PHQ-9 in broader Chinese community samples are unknown.
The consistency of the factor structure is important when a measurement is applied in a new context or cultural background [17]. The PHQ-9 has been reported to have a single factor in previous studies in the West [12], [18], [19]. However, these studies have used principle component analysis to examine the factor structure. This kind of analysis is not, in fact, appropriate for exploratory factor analysis (EFA) but rather is a data reduction strategy [20]. With the accumulating evidence of the single-factor structure of the PHQ-9 [21], efforts on the confirmatory level are needed to replicate the theoretical structure of this scale in a new sample.
This study addressed the following research questions:
- 1.
Does the Chinese version of the PHQ-9 show adequate psychometric properties with regard to the expected single-factor structure, loading of items, internal consistency, and test-retest reliability?
- 2.
Is there initial evidence for construct validity? Specifically, are the instrument scores associated with measures of negative and positive affect and health service use in the directions expected? Is the association stronger with mental health than with physical health?
- 3.
What is the prevalence of self-reported depressive symptoms in the Hong Kong population?
Section snippets
Background
In November 2007, a Hong Kong–based charitable foundation funded the University of Hong Kong's School of Public Health to develop and implement a program entitled “FAMILY: a Jockey Club Initiative for a Harmonious Society.” The project consisted of 3 parts: a family cohort study, a social marketing/public education program, and an intervention component. The data reported in this article were gathered as part of the cohort study.
The sampling frame was a list of quarters in Hong Kong. Random
Sociodemographic characteristics of the participants
Table 1 shows that there were 298 adolescents (15-17 years old), 4646 adults (aged 18-64 years old), and 1084 elderly individuals (65 years or older). The sociodemographic characteristics of our study sample were similar to census statistics of the Hong Kong population (Table 1), with effect size for proportion of those who reported no income or less than 10 000 approaching small level.
Factor structure of the PHQ-9
Based on the data from the first subsample (n = 3014), an EFA yielded a 1-factor structure. Kaiser-Meyer-Olkin
Discussion
The PHQ-9, as an instrument to assess severity of depressive symptoms, has gained growing appreciation for its brevity and tight match on the diagnostic criteria of the DSM-IV [3]. In the present study, we recruited a random household sample of 6028 participants from the community, which is a fairly representative of the general population in Hong Kong. This study provides evidence on the psychometric properties of the PHQ-9, supporting its use as a reliable and valid measurement for depressive
Acknowledgment
This study was a part of the project “FAMILY: a Jockey Club Initiative for a Harmonious Society,” which was funded by The Hong Kong Jockey Club Charities Trust. We sincerely thank Prof Gabriel M. Leung (School of Public Health, The University of Hong Kong), who led the FAMILY Project cohort study in the early phase.
References (49)
- et al.
Validity of the Brief Patient Health Questionnaire Mood Scale (PHQ-9) in the general population
Gen Hosp Psychiatry
(2006) - et al.
The Patient Health Questionnaire somatic, anxiety, and depressive symptom scales: a systematic review
Gen Hosp Psychiatry
(2010) - et al.
Validation of the Patient Health Questionnaire-9 for depression screening among Chinese Americans
Compr Psychiatry
(2008) - et al.
Comparing the FBDI-II and the PHQ-9 with outpatient substance abusers
Addict Behav
(2008) - et al.
Factor structure and predictive validity of somatic and nonsomatic symptoms from the Patient Health Questionnaire-9: a longitudinal study after spinal cord injury
Arch Phys Med Rehabil
(2010) - et al.
Twelve-month prevalence, correlates, and treatment preference of adults with DSM-IV major depressive episode in Hong Kong
J Affect Disorders
(2007) - et al.
Prevalence, treatment, and associated disability of mental disorders in four provinces in China during 2001-05: an epidemiological survey
Lancet
(2009) - et al.
Identifying depression in primary care: a literature synthesis of case-finding instruments
Gen Hosp Psychiatry
(2002) - et al.
Responsiveness of the PHQ-9 to psychopharmacological depression treatment
Psychosomatics
(2006) - et al.
Measuring depression outcome with a brief self-report instrument: sensitivity to change of the Patient Health Questionnaire (PHQ-9)
J Affect Disorders
(2004)