Screening for anxiety and depression: reassessing the utility of the Zung scales

Abstract

BackgroundWhile the gold standard for the diagnosis of mental disorders remains the structured clinical interview, self-report measures continue to play an important role in screening and measuring progress, as well as being frequently employed in research studies. Two widely-used self-report measures in the area of depression and anxiety are Zung’s Self-Rating Depression Scale (SDS) and Self Rating Anxiety Scale (SAS). However, considerable confusion exists in their application, with clinical cut-offs often applied incorrectly. This study re-examines the credentials of the Zung scales by comparing them with the Depression Anxiety Stress Scale (DASS) in terms of their ability to predict clinical diagnoses of anxiety and depression made using the Patient Health Questionnaire (PHQ).MethodA total sample of 376 adults, of whom 87 reported being in receipt of psychological treatment, completed the two-page version of the PHQ relating to depression and anxiety, together with the SDS, the SAS and the DASS.ResultsOverall, although the respective DASS scales emerged as marginally stronger predictors of PHQ diagnoses of anxiety and depression, the Zung indices performed more than acceptably in comparison. The DASS also had an advantage in discriminative ability. Using the current recommended cut-offs for all scales, the DASS has the edge on specificity, while the Zung scales are superior in terms of sensitivity. There are grounds to consider making the Zung cut-offs more conservative, and doing this would produce comparable numbers of ‘Misses’ and ‘False Positives’ to those obtained with the DASS.ConclusionsGiven these promising results, further research is justified to assess the Zung scales ability against full clinical diagnoses and to further explore optimum cut-off levels.

Prevalence and Influencing Factors of Anxiety and Depression Symptoms in the First-Line Medical Staff Fighting Against COVID-19 in Gansu

“…The self-rating anxiety scale (SAS) (7) and self-rating depression scale (SDS) (8) were used to assess anxiety and depression symptoms of medical staff respectively. Both SAS and SDS are 20-item Likert and norm-referenced scales, in which items tap physiological and psychological symptoms and are rated by participants according to how each applied to them within the past week, using a 4-point scale ranging from 1 (none, or a little of the time) to 4 (most, or all of the time) (9). The choice of SAS items is based on diagnostic criteria listed in the major American psychiatry literature, whereas the SDS taps depressive symptoms based on factor analytic studies of depression symptoms (9).…”

“…Both SAS and SDS are 20-item Likert and norm-referenced scales, in which items tap physiological and psychological symptoms and are rated by participants according to how each applied to them within the past week, using a 4-point scale ranging from 1 (none, or a little of the time) to 4 (most, or all of the time) (9). The choice of SAS items is based on diagnostic criteria listed in the major American psychiatry literature, whereas the SDS taps depressive symptoms based on factor analytic studies of depression symptoms (9). The Zung Self-Rating Anxiety/Depression Scale (SAS/SDS) has been widely applied in clinical institutions and scientific research, showing convincing results and a remarkable degree of consensus among clinicians (10).…”

Norms for Zung’s Self-rating Anxiety Scale

“…The paper focuses on Zung's Self-rating Anxiety Scale (SAS [14];) a norm-referenced screener that, in conjunction with its sister scale, the Self-rating Depression Scale (SDS, [15]) has been shown to discriminate anxiety from mood disorders [16]. Although developed in 1971, the SAS continues to be extensively used in research, particularly in medical disciplines [17].…”

“…Although developed in 1971, the SAS continues to be extensively used in research, particularly in medical disciplines [17]. The SAS has good psychometric credentials [11,14] and has been found to perform comparatively to contempory measures such as the anxiety subscale of the DASS in predicting anxiety disorder classifications based on the PHQ [16]. However, two problems have emerged in the literature regarding the Zung SAS cut-off score to indicate the presence of a disorder.…”

“…In 1980, Zung [18] reduced the cut-off point for clinical significance from that set in his seminal paper on the development of the SAS [14]. Recent research has suggested that the 1980-recommended cut-off point (a raw score of 36 or an index score of 45 [18];) is lower than ideal, and that the original 1971 cut-off (a raw score of 40; an index score of 50 [14];) produces better sensitivity and specificity figures [16]. Similar problems; that is, confusion between index and raw scores and suggestions that the currently recommended cut-off score may be too low, have also been identified for the SDS [16,17,20].…”