International Journal of Psychiatry in Clinical Practice, 2010; 14: 174–181

ORIGINAL ARTICLE

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Development of the Screener for Assessing Depression Scale: Why do we need another depression scale?*

NICOLE J. PEAK & JAMES C. OVERHOLSER Department of Psychology, Case Western Reserve University, Cleveland, OH, USA

Abstract Depression is a significant problem which affects the lives of a substantial number of people. Improved recognition of depression is an important step towards the treatment and prevention of depression. Objective. The present study examined the reliability and validity of the Screener for Assessing Depression (SAD) Scale as a measure of depression severity and as a confirmation of a major depressive episode. Method. The sample included 100 adults who were receiving inpatient psychiatric treatment (60 met criteria for a major depressive disorder and 40 met criteria for other psychological disorders without depression as a main feature). Results. Different cut-off scores were proposed in order to score the SAD Scale as a screening measure or to confirm a depressive episode. Scoring the SAD Scale according to the criteria for a major depressive episode correctly classified 87% of the sample. Conclusion. Overall, the results indicated that the SAD Scale is a reliable and valid measure for detecting a depressive episode and for assessing depression severity. Key Words: Depression, assessment

Introduction Depression is a common problem affecting as many as 16.2% of the population at some time in their life [1]. Most people fail to appreciate the serious costs associated with clinical depression. Among people who commit suicide, more than 90% of them have a diagnosable mental disorder, commonly a depressive disorder [2]. Despite its prevalence, depression often goes undetected or misdiagnosed. In fact, primary care physicians fail to detect about half of their patients with major depression [3]. Thus, it is essential to improve our efficient assessment and accurate diagnosis of depression. When clinicians choose a measure to include in their clinical practice, the optimal measure should have evidence of reliability, validity, sensitivity, and practicality [4]. Practicality means the scale is affordable, properly worded, brief, and easy to administer, score, and interpret [4]. Despite the proliferation of measures of depression [5], several problems continue to plague the assessment of depression. Some of the standard diagnostic instruments for assessing

the presence of Axis I disorders are too lengthy to administer, even when irrelevant sections are omitted. Moreover, some of these measures are difficult for patients to understand due to complex vocabulary and variations in time frame [6,7]. Lengthy administration and complex instructions can frustrate patients who are already feeling emotionally distressed [8]. In addition, many depression measures are designed to be administered and scored by trained mental health professionals [9]. Perhaps of greatest concern is that some of these measures include items that are not a part of the DSM-IV criteria for depression [10]. Elevated scores may not necessarily reflect criteria for a major depressive episode but may instead indicate other psychological disorders such as anxiety [11,12]. Thus, clinicians often fail to use structured assessment measures because the vast majority require too much time, create excessive paperwork, and are ultimately impractical [13]. These impracticalities have influenced the request for more measures that are easy to administer, score, and interpret [4].

Correspondence: James C. Overholser, PhD, Department of Psychology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 441067123, USA. E-mail: [email protected]. ∗Note: An earlier version of this report was presented at the annual meeting of the American Psychological Association, San Francisco, California, August 2007. (Received 27 July 2009; accepted 28 January 2010) ISSN 1365-1501 print/ISSN 1471-1788 online © 2010 Informa Healthcare DOI: 10.3109/13651501003661185

The Screener for Assessing Depression (SAD) Scale The Screener for Assessing Depression (SAD) Scale was developed as a new measure of depression that could be used to both detect a major depressive episode and measure the severity of the depression. The current study was designed to conduct a preliminary investigation of the reliability and validity of the SAD Scale.

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Participants The sample included 100 adult psychiatric inpatients recruited during their stay at a private psychiatric hospital. Typically, patients were recruited into the study and then completed all measures during the same day. The research participation was usually conducted within 3–5 days of admission to the hospital. Patients had participated in minimal treatment at the time they completed all measures. Most of their time had been devoted to the initial intake assessment conducted by hospital staff. Patients were classified as depressed or not depressed according to several criteria. The depressed group included 60 psychiatric inpatients that were diagnosed with a primary disorder of major depression. Initially, 66 patients signed a consent form. However two patients were removed from the analyses because the structured diagnostic interview did not support a diagnosis of major depression and four more patients were removed because their questionnaires were incomplete. Thus, all patients in the depressed group met diagnostic criteria for a major depressive disorder based on both the SCID structured interview [14] as well as the chart diagnosis provided by their attending psychiatrist who remained blind to the purpose of the present study. Depressed patients’ diagnoses included major depression – recurrent episode (86.7%) and major depression – single episode (13.4%). In addition, 36 of these depressed patients also met criteria for a secondary diagnosis. The most common co-morbid disorders included generalized anxiety disorder (13.3%), panic disorder (13.3%), PTSD (11.7%), and social phobia (8.3%). The comparison group included 40 adult psychiatric inpatients who had been hospitalized for the treatment of a nondepressive psychiatric condition. A major depressive episode was ruled out by both the SCID structured interview screening questions and the chart diagnosis provided by the attending psychiatrist who remained blind to the purpose of the present study. For the 40 patients in the comparison group, their primary diagnoses included bipolar disorder with mania (47.5%), schizophrenia (37.5%), and psychosis NOS (15.0%). Among the four patients diagnosed with a comorbid disorder, two were diagnosed with alcohol dependence, one

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was diagnosed with alcohol abuse, and one was diagnosed with substance dependence. Measures Demographic Information was collected to assess various aspects of the patient’s demographic background and psychological history. Structured Clinical Interview for DSM-IV (SCID) [14] is a diagnostic interview used to evaluate Axis I major mental disorders according to DSM-IV diagnostic criteria [10]. The SCID has been used as a standard against which to validate other diagnostic measurements [15]. The SCID has been found to display high test–retest reliability for all Axis I disorders with κ values ranging from 0.84 to 1.0 [16]. Thus, Axis I disorders can be diagnosed reliably when using the SCID [17]. Screener for Assessing Depression (SAD) Scale (Appendix A http://www.informahealthcare.com/ [10.3109/13651501003661185]) is a new measure that includes 20 items designed to evaluate the presence and severity of different symptoms of depression. The SAD Scale includes items representing the nine criteria for a major depressive episode as described by the DSM-IV [10]. Items are scored for how much each symptom has “bothered you during the past two weeks”. Possible answers include: “not at all (0)”, “a little bit (1)”, or “quite a lot (2)”, with total scores potentially ranging from 0 to 40. The SAD Scale is easy to administer, incorporates simple scoring criteria, and is written in short sentences that are easy to comprehend. The SAD Scale had a Flesch–Kincaid Grade Level readability score of 6.6, meaning that the SAD Scale could be easily read and understood by a person with a sixth-grade reading level. In the present sample, SAD scores ranged from 7 to 34 (M  23.90, SD  6.83) and displayed adequate internal consistency (α  0.94). Beck Depression Inventory (BDI) [18] includes 21 items designed to evaluate the presence and severity of different symptoms of depression. Items are arranged in multiple choice format and are scored from 0 to 3, with total scores ranging from 0 to 63. The BDI has been found to have a high index of internal consistency and adequate construct validity among depressed adult inpatients [19]. The BDI generally has good psychometric properties [11] in a variety of settings [20]. In the present sample, BDI scores ranged from 0 to 48 (M26.38, SD12.20) and displayed adequate internal consistency (α0.94). Procedures Informed consent was obtained prior to any data collection. All patients were administered the SCID

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questions relating to the diagnosis of a major depressive disorder. The SCID was administered by graduate students who were trained in diagnosing disorders and structured interviewing procedures. At the time of the SCID interview, the research assistant was aware of the patient’s chart diagnosis, but had not yet scored the SAD Scale. All questionnaires were completed by the patient in the presence of the examiner. All patients were given the same set of questionnaires in the same order. Patients with a primary diagnosis of adjustment disorder or dysthymia were not included in the study as the SAD Scale was designed to screen for a major depressive episode. Likewise, patients who met diagnostic criteria for psychosis, mental retardation, or bipolar disorder (depressed) were excluded as the etiology of these disorders varies greatly from patients who are primarily struggling with a major depressive disorder. Patients whose chart diagnoses did not match SCID diagnoses were also excluded. Results Depressed and non-depressed psychiatric inpatients were compared on demographic characteristics. There were no significant differences between the depressed patients and the comparison group on age, gender, race, marital status, and past suicide attempts (see Table I). However, depressed patients were more likely to be employed, χ2 (1, N  100)  7.48, p  0.01, more likely to have attempted suicide at some point in their life, χ2 (1, N  100)  14.73, p  0.01, and more likely to have recently (in the past 30 days) attempted suicide, χ2 (1, N  100)  28.57, p  0.01. Basic psychometric properties of the SAD Scale were evaluated. In the present sample, SAD Scale scores ranged from 7 to 34 (M  23.90, SD  6.83) and displayed adequate internal consistency

(α  0.94). Additionally, corrected item–total correlations were computed (see Table II). Thus, each individual item–total correlation was corrected to avoid overlap by excluding that particular item from the total score. It has been suggested that an item-tototal score correlation above 0.30 is considered adequate [21]. On the SAD Scale, all items correlated with the total score above 0.30, except for items 5 and 7. Additionally, the depressed patients scored significantly higher on 18 of the 20 items from the SAD Scale except for items 5 and 7. The SAD Scale was evaluated as a measure of depression severity by correlating it to the BDI. The SAD Scale was significantly associated with the BDI, r (100)  0.86, P  0.01. Additionally, depressed patients reported more depressive symptoms on the SAD Scale, t(98, N  100)  11.97, P  0.01, and on the BDI, t(98, N  100)  8.16, P  0.01, than seen in the comparison group. The items of the SAD Scale were subjected to principal components analysis (PCA) with an Oblimin rotation (see Table III). Prior to performing PCA, the suitability of data for factor analysis was assessed. Inspection of the correlation matrix revealed the presence of many coefficients of 0.3 and above. The Kaiser–Meyer–Oklin value was 0.89, exceeding the recommended value of 0.6 [22] and Bartlett’s Test of Sphericity [23] reached statistical significance, supporting the factorability of the correlation matrix. Prinicipal components analysis revealed the presence of five components with eigenvalues exceeding 1, explaining 45.48, 7.45, 6.12, 5.37 and 4.91% of the variance respectively. An inspection of the scree plot revealed a clear break after the first component for further investigation. This was further supported by the result of the parallel analysis, which showed only one component with an eigenvalue exceeding the corresponding criterion values for a randomly

Table I. Demographic characteristics of depressed and non-depressed psychiatric inpatients (N  100). Variable Age, M (SD) Gender (% male) Race % Caucasian % Asian % African American % Hispanic Marital Status (% married) Employment (% employed) Suicidality % Ever attempted (lifetime) % Recent attempt (in the past 30 days) % Past attempt (more than 30 days ago) ∗P

 0.01.

Depressed (n  60)

Non-depressed (n  40)

Test of significance

39.83 (14.23) 38.30

42.13 (11.13) 50.00

t (100)  –0.86 χ2 (1)  1.33 χ2 (3)  5.02

83.30 3.30 8.30 5.00 26.67 59.65

82.50 0.00 17.50 0.00 20.00 30.55

χ2 (1)  0.58 χ2 (1)  7.48∗

65.00 50.00 45.76

27.50 0.00 27.50

χ2 (1)  14.73∗ χ2 (1)  28.57∗ χ2 (1)  3.36

The Screener for Assessing Depression (SAD) Scale

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Table II. SAD Items, means, standard deviations, and item-total correlations for depressed and non-depressed psychiatric patients.

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SAD Scale items

Depressed (n  60) M (SD)

1. I feel sad or empty. 2. I am not interested in most activities. 3. I no longer enjoy most activities. 4. I have lost my appetite and am losing weight. 5. I am eating more and gaining weight. 6. It has been harder to fall asleep or stay asleep. 7. I have been sleeping too much and can’t get up. 8. I am restless and fidgety. 9. I move slower than usual. 10. I feel tired and out of energy. 11. I feel worthless as a person. 12. I feel guilty about things I have done. 13. It is harder than usual to think or concentrate. 14. It has been harder than usual to make decisions. 15. I have been thinking about death and dying. 16. I have been thinking about killing myself. 17. It seems harder to get along with other people. 18. I have been withdrawing from other people. 19. It seems harder for me to do my work or chores. 20. I have avoided going to school, work, or doing chores.

1.80 1.52 1.43 0.82 0.32 1.43 0.48 1.25 0.90 1.47 1.42 1.32 1.43 1.45 1.27 1.13 0.88 1.30 1.23 1.05

(0.44) (0.60) (0.67) (0.70) (0.60) (0.70) (0.70) (0.70) (0.75) (0.62) (0.72) (0.65) (0.62) (0.57) (0.73) (0.79) (0.74) (0.70) (0.72) (0.75)

Non-depressed (n  40) M (SD) 0.58 0.40 0.30 0.20 0.52 0.50 0.28 0.70 0.35 0.55 0.18 0.32 0.48 0.38 0.28 0.02 0.38 0.55 0.38 0.30

(0.64) (0.59) (0.56) (0.52) (0.68) (0.64) (0.60) (0.72) (0.53) (0.71) (0.50) (0.62) (0.64) (0.63) (0.60) (0.16) (0.63) (0.71) (0.59) (0.46)

t

Item-total correlationa

11.36∗ 9.21∗ 8.79∗ 4.77∗ –1.62 6.77∗ 1.54 3.79∗ 4.00∗ 6.79∗ 9.48∗ 7.63∗ 7.47∗ 8.91∗ 7.11∗ 8.73∗ 3.58∗ 5.22∗ 6.27∗ 5.67∗

0.79 0.78 0.81 0.44 –0.07 0.57 0.27 0.41 0.60 0.73 0.73 0.65 0.75 0.82 0.75 0.68 0.50 0.61 0.71 0.56

aEach ∗P

individual item–total correlation was corrected to avoid overlap by excluding that particular item from the total score.  0.01.

generated data matrix of the same size (20 variables  100 respondents). Additionally, the rotated solution showed all but two of the items (items 5 and 7) loading most strongly on one component. When all the items were loaded onto the single component, all the items retained strong loadings with the exception of items 5 and 7 suggesting that these two items be dropped from the SAD Scale. Thus, items 5 and 7 were removed from all subsequent analyses.

Two different statistical methods were used to evaluate the ability of the SAD Scale to detect a major depressive episode. In the first method, receiver operating characteristics (ROC) curves were used to determine the overall diagnostic accuracy of the SAD Scale in comparison to the SCID diagnosis. In addition, the sensitivity, specificity, positive predictive power, and negative predictive power of the SAD Scale was evaluated by examining optimal cut-off

Table III. Summary of factor loadings for oblimin one-factor solution of the SAD Scale (N  100). Item 1. I feel sad or empty. 2. I am not interested in most activities. 3. I no longer enjoy most activities. 4. I have lost my appetite and am losing weight. 5. I am eating more and gaining weight. 6. It has been harder to fall asleep or stay asleep. 7. I have been sleeping too much and can’t get up. 8. I am restless and fidgety. 9. I move slower than usual. 10. I feel tired and out of energy. 11. I feel worthless as a person. 12. I feel guilty about things I have done. 13. It is harder than usual to think or concentrate. 14. It has been harder than usual to make decisions. 15. I have been thinking about death and dying. 16. I have been thinking about killing myself. 17. It seems harder to get along with other people. 18. I have been withdrawing from other people. 19. It seems harder for me to do my work or chores. 20. I have avoided going to school, work, or doing chores. Eigenvalue of 9.55 accounted for 45.48% of the variance.

Factor loading

Communality

0.83 0.84 0.89 0.51 –0.08 0.62 0.30 0.48 0.63 0.78 0.79 0.72 0.79 0.84 0.78 0.75 0.56 0.69 0.77 0.62

0.68 0.70 0.78 0.26 0.01 0.39 0.09 0.23 0.40 0.60 0.62 0.52 0.62 0.70 0.61 0.56 0.32 0.48 0.60 0.38

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N. J. Peak & J. C. Overholser ROC Curve

determine the accuracy of the SAD in identifying individuals with a major depressive episode as determined by their SCID diagnosis. The SAD Scale (AUC  0.95) and the BDI (AUC  0.89) both had a high diagnostic efficiency [24]. The AUC of the SAD Scale and the BDI was significantly different in the current sample, z (100)  –2.21, P  0.03. Different cut-scores were chosen to evaluate the performances of both the SAD Scale and the BDI. For the SAD Scale to be used as a screener, it would need to be highly sensitive in order to rule out the presence of a major depressive episode without completely compromising specificity. At a cut score of 6, the SAD Scale had a sensitivity of 0.98 and a specificity of 0.58. The SAD Scale had a positive predictive value of 0.78 and a negative predictive value of 0.96. In order to use the SAD Scale to confirm a major depressive episode, it would need to be highly specific in order to rule in the presence of a major depressive episode without completely compromising sensitivity. Thus, at a cut score of 20, the SAD Scale had a sensitivity of 0.70 and a specificity of 0.95. The SAD Scale had a positive predictive value of 0.96 and a negative predictive value of 0.68. For the BDI to be used as a screener, it would need to be highly sensitive in order to rule out the presence of a major depressive episode without completely compromising specificity (see Table IV). At a cut score of 9, the BDI had a sensitivity of 0.93 and a specificity of 0.65. The BDI had a positive predictive value of 0.80 and a negative predictive value of 0.87.

1.0

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Sensitivity

0.8

0.6 Source of the curve SAD Total BDI Total Reference Line

0.4

0.2

0.0 0.0

0.2

0.4

0.6

0.8

1 - Specificity

1.0

Figure 1. Receiver operating characteristic (ROC) curves for the 18-item SAD Scale and BDI, plotting sensitivity as a function of 1-specificity. The diagonal line represents chance performance.

scores. ROC curves were used to provide information regarding diagnostic accuracy by determining (1) the area under the curve (AUC) which provides overall diagnostic accuracy and also indicates effect size and (2) the sensitivity and specificity of the scale across its full range of cut-score values. Thus, sensitivity or specificity could be calibrated as needed by considering different cut-scores. ROC curves for the SAD and BDI were plotted (see Figure 1) to

Table IV. Major depressive episode: Operating characteristics of the SAD Scale and the BDI (N100; depressed60, non-depressed40). Sensitivity SAD Scale Cut-off point 5 6 7 Cut-off point 19 20 21 BDI Scale Cut-off point 8 9 10 Cut-off point 22 23 24

Specificity

PPV

NPV

Overall diagnostic accuracy (AUC) .95

to screen MDE 1.00 0.98 0.97

0.48 0.58 0.68

0.74 0.78 0.82

1.00 0.96 0.93

0.75 0.70 0.63

0.93 0.95 0.95

0.94 0.96 0.95

0.71 0.68 0.63

to confirm MDE

0.89 to screen MDE 0.93 0.93 0.92

0.60 0.65 0.70

0.78 0.80 0.82

0.86 0.87 0.85

0.62 0.57 0.55

0.93 0.95 0.95

0.93 0.94 0.94

0.62 0.59 0.59

to confirm MDE

Structured Clinical Interview for DSM-IV was the criterion standard.

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The Screener for Assessing Depression (SAD) Scale In order to use the BDI to confirm a major depressive episode, it would need to be highly specific in order to rule in the presence of a major depressive episode without completely compromising sensitivity. Thus, at a cut score of 23, the BDI had a sensitivity of 0.57 and a specificity of 0.95. The BDI had a positive predictive value of 0.94 and a negative predictive value of 0.59. In the second method for examining the use of the SAD Scale to confirm a major depressive episode, the SAD Scale was scored according to DSM-IV criteria for a major depressive episode and evaluated for diagnostic accuracy. Sensitivity and specificity for this method were also determined. An algorithm following the DSM-IV diagnosis of a major depressive episode [10] was established to score the SAD Scale and diagnose the presence or absence of a major depressive episode. Three steps were used to score the SAD Scale according to DSM diagnostic criteria. First, the patient had to endorse a depressed mood or anhedonia. This was endorsed if either item 1 was endorsed at “quite a lot” or the sum of items 2 and 3 was greater than or equal to 2. Second, the patient had to endorse five of the nine depressive symptoms. Thus, a DSM-IV symptom was endorsed if the sum of each symptom pair (items 8 and 9, items 11 and 12, items 13 and 14, and items 15 and 16) was greater than or equal to 2. Since the symptoms of appetite (item 4), sleep (item 6), and fatigue (item 10) were only represented by one item, the patient had to endorse the item at “quite a lot” to meet either of those symptoms. Third, the patient had to report impairment in social or occupational functioning by scoring a sum score of 2 or more on the last four items (items 17, 18, 19, and 20). When scored according to DSM-IV diagnostic criteria, the SAD Scale had a sensitivity of 0.83, specificity of 0.93, a positive predictive value of 0.94, and a negative predictive value of 0.79. Overall the SAD Scale successfully classified 87% of cases, with accurate classifications for 83% of the depressed group and 92.5% for the comparison group. In order to measure the strength of association between the diagnosis according to the SCID versus the SAD Scale diagnosis, a φ correlation was computed, φ (100)  0.74, P  0.01. Discussion The SAD Scale is capable of measuring depression severity while also incorporating the DSM-IV [10] criteria for a major depressive episode. The SAD Scale displayed an adequate level of internal consistency and concurrent validity as a continuous measure of depression severity. Furthermore, depressed patients endorsed significantly more depressive

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symptoms than reported by nondepressed psychiatric patients. The SAD Scale yielded a high degree of diagnostic accuracy. Overall, these results suggest that the SAD Scale can be used to quantify the severity of depressive reactions. The SAD Scale can be used as a screening measure for a major depressive episode. If a person scores 6 or less on the SAD Scale, they are unlikely to meet criteria for a major depressive episode. However, if a person scores 20 or higher on the SAD Scale, it is very likely that a major depressive episode can be confirmed. The SAD Scale was found to be useful in differentiating individuals who are depressed from patients with other psychiatric disorders. Several advantages of the SAD Scale can be found in the present results as well as practical issues related to the ease of administration and scoring of the SAD Scale as compared to other measures of depression. Using the alternative scoring method (according to the DSM-IV diagnostic criteria for a major depressive episode), the SAD Scale correctly classified 87% of the psychiatric patients. Thus, the SAD Scale can be scored in a manner that is consistent with DSM criteria in order to confirm and help document a major depressive episode. Although the SAD Scale appears to be a useful clinical tool, there were several methodological issues that need to be addressed. First, the samples were small and unequal (depressed inpatients  60; nondepressed inpatients  40). Second, the original BDI was used in lieu of the newer BDI-II. Both the BDI and the BDI-II have demonstrated comparably high levels of internal consistency and both contain 21 symptoms associated with higher levels of selfreported depression [25]. Hence, both versions of the BDI appear interchangeable. Third, inter-rater agreement on the SCID was not checked. However, patients were included in the study only if their SCID diagnosis matched the chart diagnosis recorded by the patient’s attending psychiatrist. Chart diagnoses were based on unstructured clinical interviews made by the attending psychiatrist who was blind to the goals of the present research. Brief scales that are designed to assess depression hold potential utility for research as well as clinical practice. For example, the Patient Health Questionnaire (PHQ) shows promise as a brief measure of depression, using nine items to rate the presence and severity of depression [26], and demonstrating adequate psychometric properties [27]. However, most brief measures combine two or more criteria into one self-report item, and some depressive symptoms (e.g., indecisiveness, recurrent thoughts of death) are omitted from a brief scale. Furthermore, several prior scales have evaluated depression severity using four items [28], five items [29], six items [30], and

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eight items [31], including a two-item version of the PHQ [32]. Because such brief scales do not include all DSM-IV symptoms of a major depressive episode, they are unable to score the full diagnostic criteria, and therefore are unable to verify and support the diagnosis of a major depressive episode. Although these brief scales have been found useful for quantifying the severity of some depressive symptoms, they often lack the flexibility of the more thorough SAD Scale. The SAD Scale appears to be a reliable and valid psychometric instrument. Results from the present study suggest that the SAD Scale may be used to both quantify depression severity and confirm a major depressive episode. Moreover, the SAD Scale is a versatile measure that could be administered and scored in a variety of ways. Although not tested in the present study, trials in clinical settings suggest the SAD Scale can be adapted for interviewer administration, telephone administration, and selfreport scoring. The brief length, simple format, and ease of administration help when working with clients who have limited educational background, severely impaired vision, or when English is their second language. Future research may be able to examine the psychometric properties of the SAD Scale in assorted psychiatric care settings, medical health care facilities, or general community samples. Key points • The present study examined the reliability and validity of the Screener for Assessing Depression (SAD) Scale as a measure of depression severity and as a confirmation of a major depressive episode • Different cut-off scores were proposed in order to score the SAD Scale as a screening measure or to confirm a diagnosis of depression • Scoring the SAD Scale according to the criteria for a major depressive episode correctly classified 87% of the sample • Overall, the results indicated that the SAD Scale is a reliable and valid measure for detecting a depressive episode and for assessing depression severity Acknowledgements None. Statement of interest The authors have no conflict of interest with any commercial industry or other associations in connection with the submitted article.

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Development of the Screener for Assessing Depression Scale: Why do we need another depression scale?*.

Abstract Depression is a significant problem which affects the lives of a substantial number of people. Improved recognition of depression is an impor...
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