Elsevier

Comprehensive Psychiatry

Volume 53, Issue 1, January 2012, Pages 95-102
Comprehensive Psychiatry

The Patient Health Questionnaire-9 for measuring depressive symptoms among the general population in Hong Kong

https://doi.org/10.1016/j.comppsych.2010.11.002Get rights and content

Abstract

Objectives

The Patient Health Questionnaire-9 (PHQ-9) assesses depressive symptoms by self-report, is brief, and was developed to correspond to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for major depression. This article presents information regarding its reliability and validity and the distribution of scores in a Chinese community sample in Hong Kong.

Methods

A total of 6028 participants 15 years or older were recruited using random household sampling. They completed the Chinese version of the PHQ-9, the Happiness Scale, the Chinese Health Questionnaire, and the Short-Form 12-Item Health Survey (SF-12). Information was also gathered on health and health service use.

Results

Exploratory factor analysis and confirmatory factor analysis supported a single factor with strong loadings for all 9 items. Multiple-group analyses demonstrated that the structure can be generalized across sex and age groups (ie, adolescents, adults, and individuals 65 years or older). The internal consistency of the PHQ-9 was 0.82. The test-retest reliability over a 2-week interval was 0.76. As expected, the total score of the PHQ-9 was significantly associated with the Chinese Health Questionnaire (r = 0.49) and the Happiness Scale (r = −0.41). In addition, as expected, the relationship with the physical component subscale of the SF-12 was significantly weaker (r = −0.27) than for the mental component subscale of the SF-12 (r = −0.60). Participants with higher scores on the PHQ-9 were more likely to report having been diagnosed with depression by a physician, having chronic illness, using medicine, and using inpatient and outpatient health services. Almost 40% of participants did not report any depressive symptoms (score, 0). Self-reported symptoms at a level that would qualify for a diagnosis of major depressive disorder were provided by 1.7% of the participants.

Conclusions

Our data support the reliability and validity of the PHQ-9 in assessing depressive symptoms among the general population in Hong Kong. Its validity against diagnostic interview for major depressive disorder and its sensitivity and specificity should be determined in future studies.

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.

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