Escala de Depressão Pós-natal de Edimburgo para triagem no sistema público de saúde Edinburgh Postnatal Depression Scale for screening in the public health system

MÉTODOS: A Escala foi administrada entre o 40o e 90o dia do pós-parto, a 245 mulheres que tiveram parto em uma maternidade privada no município de Belo Horizonte (MG), entre 2005 e 2006. As participantes foram submetidas a uma entrevista psiquiátrica estruturada (Mini-Plus 5.0) utilizada como padrão-ouro para diagnóstico de depressão. Foram calculadas sensibilidade e especifi cidade da escala e utilizou-se a curva ROC para achar o melhor ponto de corte. Foi utilizado o teste t de Student para comparação das variáveis numéricas e o qui-quadrado para as variáveis categóricas. A confi abilidade foi aferida pelo coefi ciente de consistência interna α de Cronbach.


INTRODUCTION
Pregnancy and the postpartum are considered periods of high risk for the emergence of psychiatric disorders.According to Vesga-López et al, 23 between 15% and 29% of the women during these phases manifest some psychopathology.Among these, postpartum depression (PPD) is one of the most prevalent, and it may affect one out of eight women after pregnancy. 16In Brazil, a populationbased study indicated an even higher prevalence: 19.1%, which corresponds to almost one puerpera out of fi ve. 11 is likely that PPD has a multifactorial etiology, although it is not completely known.Socioeconomic aspects, 4,11 presence of psychiatric disorders before the pregnancy, 4,16 and genetic predisposition 22 are among the factors that may contribute to the emergence of PPD.
The negative impact of PPD is signifi cant not only to the patient and the family, but also to the newborn.PPD may negatively affect the mother-child interaction 14 and potentialize diffi culties in the child's neurobiological and psychological development during the fi rst stages of life. 12In addition, children of depressed mothers may present insuffi cient weight gain. 18In relation to other psychiatric disorders during the postpartum, PPD is also associated with greater risk of manifestation of aggressive behaviors, including suicide 17 and infanticide 8 attempts.
Despite its seriousness and impact on the woman and neonate, PPD is a disorder that has been frequently neglected and, therefore, underdiagnosed. 5,8Among other factors, this can be attributed to sociocultural characteristics associated with maternity that make it diffi cult for the patient and relatives to realize that such depressive symptoms are part of a disease; thus, they are predisposed to minimize and interpret them from the moral point of view. 1 Besides, some occurrences that are frequent in the postpartum period, like sleep and appetite alterations, and also fatigue, are also depressive symptoms that may, many times, hide the PPD diagnosis.Thus, when not diagnosed and treated, PPD may last many months or years, increasing the risk of other depressive episodes in the future. 13ong the attempts to develop screening tools to facilitate the identifi cation and treatment of PPD, one of the most used tools is the Edinburgh Postnatal Depression Scale (EPDS). 6,10,15Since its development, EPDS has been adapted and validated in many countries, including Brazil. 20,21It is a self-administered scale containing ten items, divided into four graduations (0 to 3).EPDS measures the presence and intensity of depressive symptoms in the last seven days.Its administration is quick and simple, and it can be used by health professionals who are not doctors.
Small differences regarding the most indicated cut-off point to identify PPD, as well as its specifi city, have been verifi ed in studies conducted in Brazil. 20,21These differences may be explained by methodological and inter-regional variations, which suggests the need of studies in other Brazilian regions to enable a better understanding of the applicability of EPDS in the public health fi eld.
The present study aimed to evaluate the psychometric properties of the Edinburgh Postnatal Depression Scale in order to use it as a screening tool in the public health system.

METHODS
The sample was composed of 245 women who were randomly selected from the hospitalization records.
They corresponded to 20% of all women whose delivery occurred in a private maternity hospital in the city of Belo Horizonte, Southeastern Brazil, between August 2005 and December 2006.
Mini-Plus 5.0 3 was utilized as gold standard for depression diagnosis.All the participants answered the Mini-Plus, which is based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders, 4 th edition (2000) (DSM-IV) 2 and was administered by a trained psychiatrist.All the interviews were conducted by the same professional who had access to the patients in their residences.Mini-Plus was administered right after EDPS.In the administration of EDPS, the Brazilian adaptation of the scale, carried out by Santos et al, 21 was used and consisted of a nurse's visit to the interviewees' homes.Besides the administration of this scale, a semi-structured interview was also conducted to obtain demographic data.Each evaluator of the tools remained blind in relation to the results obtained by the other until the end of the study.The interviews were conducted between the 40 th and the 90 th day of the postpartum.
To evaluate the discriminating validity of EPDS, the participants were divided into two groups according to the presence (or not) of the PPD diagnosis obtained by Mini-Plus.The two groups were compared in relation to EPDS score, age, level of schooling, number of gestations, and marital status.Student's t test was employed to compare the groups in the numeric variables and the chi-square was used for the categorical variables.The psychometric properties of EPDS were evaluated based on sensitivity and specifi city.To defi ne the best cut-off point, the receiver operating characteristic (ROC) curve was used.The scale's reliability was calculated by means of Cronbach's coeffi cient α of internal consistency.
The study was approved by the Research Ethics Committee of Universidade Federal de Minas Gerais (Process 227/05).All the participants signed an informed consent form.

RESULTS
The participants' age (mean=30.7;standard deviation=5.8)ranged from 16 to 50 years.All the participants had at least eight years of formal schooling, and the majority of them completed the higher education level (n=130; 53.1%).In relation to marital status, 48 women were single (19.6 %), 191 were married (78.0%), four lived with their partners (1.6%) and two were separated (0.8%).
Sixty-six women (26.9% of the sample) were diagnosed with PPD.No differences were observed between groups in relation to age, level of schooling, number of previous deliveries and marital status (Table 1).
Concerning the properties of EPDS, Cronbach's coeffi cient alpha was 0.87, indicating that the tool has high internal consistency.The Figure shows the results of the analysis of the ROC curve for the total score of EPDS.The total area of the ROC curve was 0.937 (standard error = 0.20; p<0.001), indicating that EPDS has excellent capacity to discriminate women with PPD.Table 2 presents the results of specifi city and sensitivity, positive predictive value and negative predictive value of EPDS for the cut-off points 9, 10, 11, 12 and 13.

DISCUSSION
In general, the studies that validated EPDS show high sensitivity and specifi city, as well as high predictive value. 10,15,20,21A study conducted in Brasília 21 (Federal District) included 69 women who presented an average time of puerperium of 10.2 weeks.According to the  19 (39.4%) (Vitória, ES).The differences between studies may have been produced by the methodological aspects related to the method of diagnosis, the subjects' sociodemographic characteristics, as well as the puerperium period in which the woman was evaluated.In addition, possible inter-regional differences should be clarifi ed.Future studies using uniform evaluation procedures in different Brazilian regions may contribute to clarify this question.
Our study corroborates the literature, suggesting that EPDS constitutes an adequate screening tool for postpartum depression, and that it can be implemented in the public health network in view of its easy and quick administration, low cost and the fact that it can be administered by any health professional.The broad use of the scale can be associated with an increase in the indexes of diagnosis and treatment of the disease, thus minimizing its possible harmful effects on mother and child.

Figure 1 .
Figure 1.ROC curve for performance in EPDS in comparison to the postpartum depression diagnosis based on DSM-IV criteria (gold standard).Municipality of Belo Horizonte, Southeastern Brazil, 2005-2006.

Table 1 .
Sociodemographic characteristics of the groups of participants with and without postpartum depression diagnosis.Municipality of Belo Horizonte, Southeastern Brazil 2005-2006.

Table 2 .
Sensitivity, specifi city, positive predictive value and negative predictive value in the Edinburgh Postnatal Depression Scale.Municipality of Belo Horizonte, Southeastern Brazil 2005-2006.