Design
This cross-sectional study is based on mining of the electronic patient database of the second largest health fund in Israel, Maccabi Health Services (MHS). Data of sociodemographic, medical and lifestyle factors were collected for the women included, for the period of the pregnancy and 6 weeks postpartum.
Setting and population
Nursing staff are responsible for administering the EPDS in mother and child clinics in Israel; 48% of these clinics are governmental, 48% belong to the healthcare funds and 4% are municipal. All women in MHS who filled the EPDS in the healthcare fund clinics during 2015–2016 were included in the current study. Data from governmental and municipal mother and child clinics were not available for this study.
Variables
The outcome variable of perinatal depression was based on the EPDS. The EPDS [19] is a validated, easily administered and widely used scale that was designed specifically to assess perinatal depression. This scale was recommended for assessment of perinatal depression by a systematic review [20]. Among its strengths are its brevity and the absence of the word “depression”.
The EPDS comprises 10 questions that access information about the respondent’s mood and depressive symptoms during the 7 days preceding its administration. The response to each question is scored 0–3; thus, the highest possible score is 30. In this study, a score of ≥10 was classified as depression. We used one EPDS score for every woman who filled the EPDS (if filled twice, the lower score was taken to ensure a conservative estimate).
Although the DSM-V states a cutoff point of 4 weeks for perinatal depression, we included in this study all women who filled the EPDS during pregnancy and until 9 weeks postpartum, according to the protocol of the Israel Ministry of Health.
Predictor variables accessed included sociodemographic, medical and lifestyle factors.
The sociodemographic factors examined were age [< 25, 25–40, > 40 years], living in the peripheral region of the country (yes/no), socioeconomic status (SES) (categorical) and population group [Arab, Orthodox Jew, other]). The classification of residence in a peripheral area is determined by geographical distance from the center of the country and distance from large cities (based on a measure of the Israel Central Bureau of Statistics). SES was determined according to residence. In 2008, the state of Israel was divided into 210 localities, for the calculation of SES. Each locality was ranked from 1 to 10 (10 represents the highest SES), according to 16 factors, including education, employment, and car ownership.
The medical factors examined were medical conditions (cardiovascular disease [yes/no], chronic diabetes mellitus [yes/no], hypertension [yes/no]), medications (the use of antidepressant medications [none, ≤3 months, > 3 months]), and blood test results (haemoglobin [≤10.5 d/dl or > 10.5 g/dl], ferritin, iron, vitamin B12, folic acid, vitamin D, TSH and c-reactive protein [continuous variables]).
Medical conditions and blood tests were considered according to information recorded in the files of the women included in the study. Iron, ferritin, vitamin D, vitamin B-12, folic acid, C-reactive protein and thyroid stimulating hormone (TSH) were not tested in all pregnant women; therefore, data were available for only some of them. If more than one value was available for a given parameter, the lowest value was considered in the analysis, except for TSH, for which both minimal and maximal values for each woman were entered into the analysis. In this study there was no access to measures of glucose and the glucose tolerance test.
The lifestyle factors examined were: smoking habits (never, past smoking, current smoking), as recorded by medical staff.
Statistical analysis
A descriptive analysis of the participants was conducted. Characteristics of the women who filled the EPDS were compared with all members of MHS who delivered in the study period. This was to assess the similarity of the sample population with the general population of parturients, in regard to age, residence in the periphery and population group (Arabs, orthodox Jewish).
Univariate analysis was performed to compare women who were classified as having perinatal depressive symptoms (a score ≥ 10 on the EPDS test) and those without these symptoms. The Chi square test was used to investigate associations of categorical variables. The Independent T test was used for comparing normally distributed data. A p-value of less than 0.05 was considered statistically significant. Crude odds ratios (ORs) were based on the univariate analysis. Variables that were statistically significant in the univariate analysis were entered into a logistic regression analysis that assessed adjusted odds ratios (aORs) for associations with perinatal depression symptoms according to the EPDS. The Statistical Package for Social Sciences (SPSS) software version 21 was used for data analysis.