«Chilean experimental version of the State-Trait Depression Questionnaire (ST-DEP): Trait sub-scale (T-DEP)1 Pablo Vera-Villarroel2 (Universidad de ...»
© International Journal of Clinical and Health Psychology ISSN 1697-2600
2008, Vol. 8, Nº 2, pp. 563-575
Chilean experimental version of the State-Trait
Depression Questionnaire (ST-DEP): Trait
Pablo Vera-Villarroel2 (Universidad de Santiago de Chile USACH, Chile),
Gualberto Buela-Casal (Universidad de Granada, España),
Karem Celis-Atenas (Universidad de Santiago de Chile USACH, Chile),
Natalia Córdova-Rubio (Universidad de Santiago de Chile USACH, Chile), Natalia Encina-Olea (Universidad de Santiago de Chile USACH, Chile), and Charles D. Spielberger (University of South Florida, USA) (Received June 15, 2007 / Recibido 15 de junio 2007) (Accepted October 9, 2007 / Aceptado 9 de octubre 2007) ABSTRACT. This instrumental study presents the first validity and reliability data for the Trait subscale (T-DEP) of the Chilean experimental version of the State and Trait Depression Inventory (ST-DEP): Euthymia and Dysthymia. The data were obtained from a sample of 300 university students. The internal consistency values for the TDEP were high (.90). The test-retest values from eight weeks time interval (fifty six days) were elevated (.78). A factorial analysis of the principal components revealed a principal factor for all of the constructed items in this experimental version of the TDEP. The last, promax rotation showed two clear main factors similar in size: negative affectivity (Dysthymia) and positive affectivity (Euthymia). The convergent validity indexes for the Beck Depression Inventory and the Zung Self Rating Depression Scale, were also high, with indexes ranging from.64 to.71. The correlation between StateTrait Anxiety Inventory and the depression scales used in this study was high (between.63 and.78), once again indicating the usual overlapping between anxiety and depression seen in most depression inventories.
The study was conducted thanks to the contributions of the investigation project Dicyt of the Universidad de Santiago de Chile.
Correspondence: Escuela de Psicología de la Universidad de Psicología de Chile USACH. E-mail:
email@example.com 564 VERA-VILLARROEL et al. State-Trait Depression Questionnaire KEYWORDS. State. Trait. Depression. Instrumental study.
RESUMEN. Este estudio instrumental presenta los primeros datos de validez y fiabilidad de la sub-escala Rasgo (T-DEP) de la versión experimental chilena del Inventario de Depresión Estado y Rasgo (ST-DEP): Eutimia y Distimia. Los datos fueron obtenidos de una muestra de 300 estudiantes universitarios. La consistencia interna del T-DEP fue elevada (0,90). El valor del test retest para el T-DEP, con un intervalo de ocho semanas, fue elevado (0,78). Un análisis factorial de componentes principales presenta
un factor principal constituido por todos los ítems redactados para la versión experimental chilena. La posterior rotación promax muestra dos claros factores principales:
afectividad negativa (Distimia) y afectividad positiva (Eutimia). Índices de validez convergente en relación al Inventario de Depresión de Beck y la Escala de Depresión de Zung fueron altos, con índices que fluctuaron entre 0,64 a 0,71. La correlación entre la medida de ansiedad estado-rasgo y las medidas de depresión utilizadas muestran índices altos (entre 0,63 y 0,78), manifestando el solapamiento existente entre depresión y ansiedad.
PALABRAS CLAVE. Estado. Rasgo. Depresión. Estudio instrumental.
Depression is the most prevalent of the mental disorders, acquiring great proportions in the modern life (Dowd, 2004). In Chile the prevalence varies between 7.5 to 10%, registering the highest prevalence in the group from 20 to 45 years (Ministerio de Salud de Chile, 2001; Vicente, Rioseco, Saldivia, Kohn, and Torres, 2002). Studies with population’s sample older than 15 years, estimate that the prevalence of this dysfunction is superior to that of many Latin American countries (Araya, Madariaga, Ureta, Tomé, and Bustos, 2002). Among the assisted in the primary attention level, 30% suffer from depressive symptoms (Ministerio de Salud de Chile, 2001). The detection of the depressive disorder and its hidden forms (for physical symptoms or diverse uneasiness) frequently produce confusion and frustration in the non specialist doctors and in the health teams, since it generates repeated medical consultations, exams, inadequate treatments or interconsultation which do not heal and elevate the costs (Ministerio de Salud de Chile, 2001). Gempp and Chesta (2007) outline that, in the historical development of the discipline, the psychological tests are a great technological advance, used in all the areas of the professional development. Nevertheless, it is crucial to systemize the psychometrically valid instruments for their correct use. This shows the importance of generating efficient, precise and useful methods for the evaluation of depression.
An important obstacle to achieve these objectives is the difficulty to understand the nature of depression itself. The majority of the scales tend to confuse state and trait scores in depression and the genuine symptoms that compose it, which increases the risk of emitting erroneous or imprecise diagnoses (Agudelo et al., 2005; Spielberger, Carretero-Dios, De los Santos-Roig, and Buela-Casal, 2002a, 2002b; Spielberger, Ritterband, Reheiser, and Brunner, 2003). The difficulties in evaluating depression, mentioned above, led Spielberger´s group to develop the State and Trait Depression Questionnaire (ST-DEP) which seeks to be constituted in a much more specific measure, Int J Clin Health Psychol, Vol. 8, Nº 2 VERA-VILLARROEL et al. State-Trait Depression Questionnaire when limiting its content to the affective components of depression and the differentiation between positive affectivity and negative affectivity, in terms of both the occurrence or frequency (trait) and intensity at the moment of the evaluation (state) (Agudelo et al., 2005).
In their investigations, two very strong factors were identified, which were defined by items that described the presence or absence of state and trait depression symptoms.
The best depression-present (Dysthymia) and depression-absent (Euthymia) items were selected to form 20-item State (S-DEP) and Trait (T-DEP) depression scales, each with 10 items, 5 for Dysthymia and 5 for Euthymia subscales. The alpha coefficients for the S-DEP and T-DEP scales and subscales for the total sample, and in separate analyses for females and males, were.90 or higher, indicating strong internal consistency. The T-DEP scale was highly correlated with the Beck Depression Inventory (BDI) (Beck, Rush, Shaw, and Emery, 1979), Zung Self-Rating Depression Scale (SDS) (Zung, 1965), and Center for Epidemiologic Studies Depression Scale (CES-D) (Radloff, 1977), (Mdn.
r =.80), providing impressive evidence of concurrent validity (Spielberger et al., 2003).
Krohne, Schumukle, Spaderna, and Spielberger (2002) report psychometric properties of the German version of the State Trait Depression Questionnaire (ST-DEP) in a sample of university students in comparison to the sample of American university students. No gender differences were found in this German sample. The correlation between de German version and the other depression measures was between.43 and.82 and the correlation of the Trait subscale and anxiety measure was.88 for the American sample and.83 for the German sample.
Spielberger et al. (2002a, 2002b) conducted the first known study in Spanish. This study presents the first Spanish validity and reliability data for the Trait subscale. The dimensional structure was replied, internal consistency values for the T-DEP were high (.95). The convergent validity indexes for the Beck Depression Inventory (Beck et al., 1979), the Zung Self-Rating Depression Scale (Zung, 1965), and the Peñate Basic Depression Questionnaire (Peñate, 2001) were also high, with indexes ranging from.68 to.82. The correlation between State-Trait Anxiety Inventory (Spielberger et al., 1970) and all scales used in this study was high, once again indicating the usual overlapping between anxiety and depression seen in most depression inventories (Agudelo et al., 2005; Spielberger et al., 2002a, 2002b).
For the diagnoses benefits of the ST-DEP and considering the high prevalence of depression in Chile, which makes it a public health issue, the objective of this instrumental study (Carretero-Dios and Pérez, 2007; Montero and León, 2007) is to report the psychometric properties of the Chilean experimental version of the adapted T-DEP, following the procedure of the original Spanish adaptation (Spielberger et al., 2002a, 2002b) in a sample of university students.
years with a standard deviation of 2.19. The mean age for men was 20.68 years with a standard deviation of 2.40.
Instruments The Beck Depression Inventory (BDI)-Revised version (Beck, Rush, Shaw, and Emery, 1983) and Zung’s Self-Rating Depression Scale (SDS) (Conde, Escriba, and Izquierdo, 1970a, 1970b; Zung, 1965) were selected, which according to Spielberger et al. (2003) evaluate a quality similar to trait as it is asked how frequent the symptoms have been in the past week including today (Beck and Steer, 1993; Vázquez and Sanz, 1997, 1999). Lastly, the Trait scale from the State-Trait Anxiety Scale (STAI) (Spielberger et al., 1970) was selected. The following section describes each one of the chosen instruments and the results obtained for the Chilean sample.
– Chilean Experimental Version for Trait depression evaluation (T-DEP). The Chilean experimental version was created from the Spanish final version of T-DEP (10 item) (Agudelo, 2005) and the original English version (Spielberger, 1999). For this purpose, alternative items were created from the Spanish version to reflect Chilean meaning differences, maintaining the English sense.
The objective of the Trait scale of the inventory is to identify the occurrence frequency (trait) for the affective component of Depression. The area of content is the frequency of negative affectivity (Dysthymia) and positive affectivity (Euthymia). The instructions ask each subject to choose one of the numbers next to the “statement that people have used to describe themselves”, and to “put a circle around the number of the statement that best indicates how he/she generally feels”. The response options indicate frequency and offer four alternatives: 1 (almost never), 2 (sometimes), 3 (often), and 4 (almost always). In order to obtain the subject’s score, the chosen response option (1, 2, etc.) is equivalent to the assigned scores for the items referred to Dysthymia (negative affectivity).
The reverse score (1= 4; 2= 3; 3= 2; 4= 1) is given to the items which indicate Euthymia. The final score for the trait sub-scale is obtained by adding the values, with a possible range from 16 to 64. The experimental version of the test is composed of a total of 16 items, 8 for Dysthymia and 8 for Euthymia.
– Beck Depression Inventory (BDI)-Revised version (Beck et al., 1983). The scale contains a total of 21 items. Each item has four possible response options ranging from 0 (depression absence) to 3 (maximum depression), with a total test score ranging between 0 and 63. The instructions ask the subject to respond by circling the number (0, 1, 2, or 3) next to the statement in each group that describes best “how he/she has felt during the past week, and including the present day”. The objective of the BDI is to evaluate the severity of the cognitive, affective, behavioural and physiological symptoms of depression (Alvarado, Vega, Sanhueza, and Muñoz, 2005; Beck, Steer, and Garbin, 1988; Ibáñez, Peñate, and González, 1997). The BDI reliability and validity have been widely substantiated in clinical, as well as normal samples (Spielberger et al., 2003).
Int J Clin Health Psychol, Vol. 8, Nº 2 VERA-VILLARROEL et al. State-Trait Depression Questionnaire An elevated alpha for internal consistency was observed in the Spanish validation of the test (Sanz and Vazquez, 1998), carried out in both clinical and normal populations,.83 and.90, respectively. The values of the test-retest range between.60 and.72 and the concurrent validity indexes range between.68 and.89. The Sanz and Vázquez (1998) study found low correlations for the divergent validity, ranging between.11 and.45, with different anxiety scales.
– Zung Self-Rating Depression Scale (SDS) (Conde et al., 1970a, 1970b; Zung, 1965). This scale is composed of 20 items and assesses the severity of depression.
It analyzes affective components, as well as cognitive, psychomotor, and physiological/somatic components. The subjects completing this test should specify for each one of the items “How long has each situation affected your selfesteem at the present moment, or more, during this last week”. A subject must rate themselves on a 4 point frequency scale: 1 (none or little of the time), 2 (some of the time), 3 (good part of the time), and 4 (most or all of the time).
The subjects’ response ratings from 1 to 4 are summed up for each of the 20 items, yielding a possible total score range from 20 to 80. The normal and clinical populations in the Spanish adaptation (Conde et al., 1970a, 1970b;
Conde and Esteba, 1975, 1976a, 1976b), support the test’s high validity and reliability, reaching alpha values around.85, similar to the.86 value found by Ritterband and Spielberger (1996) for the normal sample. Spielberger et al.
(2003) note a correlation of.77 with the BDI and.83 with the CES-D. Rivera, Corrales, Cáceres, and Piña (2007) describe the psychometric properties of the scale in a group of people that attend regularly the ambulatory centre for the Prevention and Attention to HIV/AIDS in the city of Hermosillo (Mexico), this scale shows an estimated reliability of.89, and in the construct validity the factorial analysis showed a structure of three factors.
– State-Trait Anxiety Inventory (STAI)-Trait sub-scale (Spielberger et al., 1970).