Methodological artifacts in dimensionality assessment of the Hospital Anxiety and Depression Scale (HADS)

https://doi.org/10.1016/j.jpsychores.2012.11.012Get rights and content

Abstract

Objective

The Hospital Anxiety and Depression Scale (HADS) is a brief, self-administered questionnaire for the assessment of anxiety and depression in hospital patients. A recent review [7] discussed the disagreement among different studies with respect to the dimensionality of the HADS, leading Coyne and Van Sonderen [8] to conclude from this disagreement that the HADS must be abandoned. Our study argues that the disagreement is mainly due to a methodological artifact, and that the HADS needs revision rather than abandonment.

Method

We used Mokken scale analysis (MSA) to investigate the dimensionality of the HADS items in a representative sample from the Dutch non-clinical population (N = 3643) and compared the dimensionality structure with the results that Emons, Sijtsma, and Pedersen [11] obtained in a Dutch cardiac-patient sample.

Results

We demonstrated how MSA can retrieve either one scale, two subscales, or three subscales, and that the result not only depends on the data structure but also on choices that the researcher makes. Two 5-item HADS scales for anxiety and depression seemed adequate. Four HADS items constituted a weak scale and contributed little to reliable measurement.

Conclusions

We argued that several psychometric methods show only one level of a hierarchical dimensionality structure and that users of psychometric methods are often unaware of this phenomenon and miss information about other levels. In addition, we argued that a theory about the attribute may guide the researcher but that well-tested theories are often absent.

Introduction

The Hospital Anxiety and Depression Scale (HADS [1], [2]) is a brief, self-administered questionnaire for the assessment of the presence and the severity of anxiety and depression in physically ill patients. The HADS consists of two 7-item scales, one measuring anxiety and the other depression. Somatic indicators of anxiety and depression are not part of the HADS because physical illness may interfere with somatic symptoms [3]. For the classification of individuals as anxious or depressed, researchers use the total scores on the 7-item Anxiety and Depression scales [4].

Two literature reviews [5], [6] concluded that the HADS is a psychometrically sound, 2-dimensional questionnaire for measuring anxiety and depression. More recently, Cosco, Doyle, Ward, and McGee [7] reported several studies that failed to replicate the HADS' expected 2-dimensional structure and, moreover, disagreed on the dimensionality of the HADS. Coyne and Van Sonderen [8] concluded from this result that the HADS should be abandoned. This article is a response to the literature reviews and has two goals.

Different researchers use different psychometric methods to analyze their HADS data sets. The first goal was to argue that the use of different psychometric methods rather than different psychological traits driving responses to the items is responsible for the different dimensionality results. Hence, the search for the “true” HADS structure confounds the effect that different traits exercise on patients' responses with a method effect, and it is the method effect rather than the trait effect that likely produces the divergent dimensionality results found in different studies. Thus, the disagreement about the dimensionality of the HADS mainly refers to a methodological artifact. We believe a discussion of the failure to replicate a 2-dimensional structure should concern the method effect, and should analyze the ways that different methods produce different results that are typical of the method more than the data set.

The second goal of this article was to study the HADS dimensionality using Mokken scale analysis (MSA) [9], [10] as Cosco et al. [7] recommended. Mokken scale analysis is a scaling method that can be used for the assessment of Likert-items [11], [12], [13], that includes a methodology for finding the dimensionality of a data set, and has the effect of reducing the method artifact. Mokken scale analysis is particularly suited for revealing the dimensionality of questionnaires that are based on a hierarchical trait structure [12], [19], and we argue that the HADS data reflect this hierarchical structure.

Previous studies (e.g., [14], [15], [16], [17]) found different dimensionality structures in samples from a non-clinical population and a cardiac-patient population. Hence, we also compared MSA results we found in a Dutch non-clinical sample with MSA results that Emons et al. [11] obtained from a Dutch cardiac-patient sample so as to explain why studies investigating different populations produce different dimensionality-structure results. The Dutch non-clinical sample data were reused with permission by Denollet (e.g., [18]). The secondary data analysis using MSA was original and not done previously by other researchers using these data.

The outline of this article is as follows. First, we discuss the HADS' hierarchical dimensionality structure, and discuss how different psychometric methods used to study the HADS' dimensionality deal with hierarchical trait structures and produce dimensionality results typical of the method. Second, we use MSA to study the HADS' hierarchical structure in a sample from a non-clinical population and compare the results with the MSA results that Emons et al. [11] obtained from a sample of cardiac patients. Third, we discuss the relation of the MSA results to previous findings from Rasch-model analysis, exploratory factor analysis, and confirmatory factor analysis. Finally, we discuss the consequences of the MSA results for the use of the HADS.

Section snippets

Hierarchical attribute structure and method effects

Psychological attributes often have a hierarchical structure [19]. In response to Coyne and Van Sonderen [8], Norton, Sacker, and Done [20] also made this point, based on the argument that researchers using the same dimensionality-assessment method usually found the same dimensionality structure for the HADS but researchers using different methods found different dimensionality structures. Hence, their point is that different methods find different levels of the hierarchy but that the hierarchy

Participants

For the non-clinical sample, Kupper and Denollet [18] approached 3708 Dutch participants of which 3643 (98.2%) participants filled out the HADS. Two gender levels and six age levels (20–29, …, 60–69, 70–80 years) served as stratification criteria, and quota sampling produced twelve equally sized groups. A local ethics committee at Tilburg University (protocol number: 2006/1101) approved this study. Research assistants approached participants personally or by phone. After the study's purpose had

Mokken scale analysis

For each lower bound c, the automated item selection procedure and its genetic-algorithm version yielded the same item partitionings. Table 1 shows the item partitionings for lower bounds c equal to 0, .3, and .45; other c values did not provide additional information. For c = 0, all items were selected in one scale. For lower bound c = .3, the automated item selection procedure produced a single scale containing 11 items. Items A6, D5, and D7 were unscalable. For higher c values, the automated

Discussion

Fig. 1 summarizes the MSA results with respect to the HADS' hierarchical structure. At the top level of Fig. 1, all 14 items are selected in a single scale. This one-dimensional solution corresponds to results obtained from Rasch analysis and MSA for c = 0. At the second level of Fig. 1, 10 items constitute a single psychological distress scale whereas items A4, A6, D5, and D7 are no longer in the scale. This predominantly one-dimensional solution, in which a few items do not fit, corresponds to

Acknowledgment

The authors thank Johan Denollet for making the Dutch non-clinical sample data available.

References (45)

  • S Moorey et al.

    The factor structure and factor stability of the Hospital Anxiety and Depression Scale in patients with cancer

    The British Journal of Psychiatry

    (1991)
  • RJ Mokken

    A theory and procedure of scale analysis

    (1971)
  • K Sijtsma et al.

    Introduction to nonparametric item response theory

    (2002)
  • WHM Emons et al.

    Dimensionality of the Hospital Anxiety and Depression Scale (HADS) in cardiac patients: comparison of Mokken scale analysis and factor analysis

    Assessment

    (2012)
  • AAJ Wismeijer et al.

    A comparative study of the dimensionality of the self-concealment scale using principal component analysis and Mokken scale analysis

    Journal of Personality Assessment

    (2008)
  • H Andrea et al.

    Anxiety and depression in the working population using the HAD Scale—psychometrics, prevalence and relationships with psychosocial work characteristics

    Social Psychiatry and Psychiatric Epidemiology

    (2004)
  • T Hunt-Shanks et al.

    A psychometric evaluation of the Hospital Anxiety and Depression Scale in cardiac patients: addressing factor structure and gender invariance

    British Journal of Health Psychology

    (2010)
  • CR Martin et al.

    Factor structure of the Hospital Anxiety and Depression Scale in coronary heart disease patients in three countries

    Journal of Evaluation in Clinical Practice

    (2008)
  • A Mykletun et al.

    Hospital anxiety and depression (HAD) scale: factor structure, item analyses and internal consistency in a large population

    The British Journal of Psychiatry

    (2001)
  • SP Reise et al.

    Factor analysis and scale revision

    Psychological Assessment

    (2000)
  • G Rasch

    Probabilistic models for some intelligence and attainment tests

    (1960)
  • RR Meijer et al.

    Theoretical and empirical comparison of the Mokken and the Rasch approach to IRT

    Applied Psychological Measurement

    (1990)
  • Cited by (25)

    • Parental emotional distress after discharge from the neonatal intensive care unit: A pilot study

      2020, Early Human Development
      Citation Excerpt :

      The Dutch translation of the Hospital Anxiety and Depression Scale (HADS) [24–26] was used to assess total emotional distress and symptoms of anxiety and depression in both mothers and fathers. Dutch reference data of the HADS was made available to us by the research group of the University of Tilburg, the Netherlands [27]. Data of 265 reference mothers and 131 reference fathers was selected and matched to the parents of VPT infants, based on parental age (between 20 and 40 years), and household (at least one child [age unknown]).

    • Screening for depression in acute coronary syndrome patients: A comparison of Patient Health Questionnaire-9 versus Hospital Anxiety and Depression Scale-Depression

      2019, Journal of Psychosomatic Research
      Citation Excerpt :

      Burns et al. suggested HADS should not be recommended for patients with ischemic heart disease because of its poor psychometric properties [43]. But a study on the dimensionality assessment of HADS indicated that different psychometric methods emphasized different dimensional structures [44]. The diverse methods rather than the items of HADS produced the heterogeneity on dimensionality structure [45,46].

    • The dimensional structure of the MacNew Health Related Quality of Life questionnaire: A Mokken Scale Analysis

      2015, Journal of Psychosomatic Research
      Citation Excerpt :

      MSA is particularly useful in order to investigate the dimensionality of scales. By employing a “bottom up” clustering search procedure using preselected cutoff points for item scalability, MSA allows, unlike other techniques, analysis of the dimensional structure of a scale on different hierarchical levels [9]. Our work comprises two parts.

    • Revisiting the dimensionality of the Hospital Anxiety and Depression Scale in an international sample of patients with ischaemic heart disease

      2014, Journal of Psychosomatic Research
      Citation Excerpt :

      The initial unrotated factor found in EFA studies indicates a general factor and it is only when this is rotated that the anxiety-depression factorizarion emerges [19]. Straat et al. have also noted the tendency for EFA to detect heterogeneity in the inter-item correlation matrix, suggesting multidimensionality even when the factor structure is actually weak [36]. Finally, the fact that IRT studies of the HADS consistently produce unidimensional solutions [13] also accords with the presence of a strong dominant factor [19].

    • Preferred Self-Administered Questionnaires to Assess Depression, Anxiety and Somatization in People With Musculoskeletal Pain – A Modified Delphi Study

      2020, Journal of Pain
      Citation Excerpt :

      This is in line with the current literature as the factor structure of the HADS seems to vary with the method of analysis that is used.11 Some researchers advise revision of the HADS rather than abandonment.34 Also according to the qualitative comments, the appropriateness of the recommended questionnaires for anxiety may depend on the situation.

    View all citing articles on Scopus
    View full text