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. Author manuscript; available in PMC: 2012 Feb 1.
Published in final edited form as: J Psychiatr Res. 2010 Jun 9;45(2):213–219. doi: 10.1016/j.jpsychires.2010.05.017

Validity of Depression Rating Scales during Pregnancy and the Postpartum Period: Impact of Trimester and Parity

Shuang Ji 1, Qi Long 1,4, D Jeffrey Newport 2, Hyeji Na 2, Bettina Knight 2, Elizabeth B Zach 2, Natalie J Morris 2, Michael Kutner 1, Zachary N Stowe 2,3
PMCID: PMC2945623  NIHMSID: NIHMS208557  PMID: 20542520

Abstract

The objective of the current study was to delineate the optimal cutpoints for depression rating scales during pregnancy and the postpartum period and to assess the perinatal factors influencing these scores. Women participating in prospective investigations of maternal mental illness were enrolled prior to 28 weeks gestation and followed through 6 months postpartum. At each visit, subjects completed self-rated depression scales – Edinburgh Postnatal Depression Scale (EPDS) and Beck Depression Inventory (BDI) and clinician-rated scales – Hamilton Rating Scale for Depression (HRSD17 and HRSD21). These scores were compared to the SCID Mood Module for the presence of fulfilling diagnostic criteria for a major depressive episode (MDE) during 6 perinatal windows: preconception; first trimester; 2nd trimester; 3rd trimester; early postpartum; and later postpartum. Optimal cutpoints were determined by maximizing the sum of each scale’s sensitivity and specificity. Stratified ROC analyses determined the impact of previous pregnancy and comparison of initial to follow-up visits. A total of 534 women encompassing 640 pregnancies and 4025 follow-up visits were included. ROC analysis demonstrated that all 4 scales were highly predictive of MDE. The AUCs ranged from 0.857 to 0.971 and were all highly significant (p<0.0001). Optimal cutpoints were higher at initial visits and for multigravidas and demonstrated more variability for the self-rated scales. These data indicate that both clinician-rated and self-rated scales can be effective tools in identifying perinatal episodes of major depression. However, the results also suggest that prior childbirth experiences and the use of scales longitudinally across the perinatal period influence optimal cutpoints.

Keywords: Depression, Pregnancy, Postpartum, Beck Depression Inventory, Hamilton Rating Scale for Depression, Edinburgh Postnatal Depression Scale

INTRODUCTION

Maternal depression during pregnancy and the postpartum period, i.e. perinatal depression, is a common problem that has been the focus of extensive investigation. Studies examining the prevalence of perinatal depression have demonstrated considerable variability that is a consequence, at least in part, of the assessment method used to identify the presence of depression, the timing of the assessment, and population characteristics (Gaynes et al 2005). Authors of one review recommended that more precise determinants of the occurrence of perinatal depression are needed to estimate disease burden more accurately (Gaynes et al 2005).

Depressive symptoms are common in pregnancy with most studies reporting rates comparable to non-gravid women (Cutrona 1983; Kumar & Robson 1984; Watson et al 1984; Gotlib et al 1989; O’Hara et al 1991). A meta-analysis of depression during pregnancy (Bennett et al 2004), utilizing data encompassing 19,284 gravidas from 21 studies in which depression was assessed by a structured clinical interview or self-rated scale such as the Beck Depression Inventory (BDI) (Beck et al 1961), or the Edinburgh Postnatal Depression Scale (EPDS) (Cox et al 1987), estimated the prevalence of depression as 7.4% in the first trimester, 12.8% in the second trimester, and 12.0% in the third trimester. However, the data were inadequate to render conclusions regarding comparative risk between trimesters. Furthermore, the authors reported that the BDI produced significantly higher prevalence estimates, whereas EPDS estimates were statistically equivalent to those of structured clinical interviews.

Depression during the postpartum period has also garnered considerable attention. An earlier meta-analysis by O’Hara and Swain (1996), encompassing 12,810 postpartum women from 59 studies utilizing a clinical interview or self-report scale, estimated the prevalence of depression in the postpartum period at 13.0%. Similar to the pregnancy data, self-report measures yielded higher estimates of postpartum depression than clinician-administered assessments. The postpartum timing of the assessment did not significantly affect the prevalence estimates in this meta-analysis. A review of the prevalence studies found that 7.1% may experience a major depressive episode (MDE) during the first 3 months postpartum (Gavin et al 2005). Despite the historical assumption of increased vulnerability to depression in the postpartum period, the literature has not definitively demonstrated an increased risk (Gavin et al 2005). In contrast, a recent large-scale epidemiological study provided evidence of increased risk for major depression in the postpartum period compared with non-pregnant/non-postpartum women (adjusted odds ratio: 1.52; 95% CI: 1.07–2.15) (Vesga-Lopez et al 2008). Moreover, women are more likely to require psychiatric admission for depression during the postpartum period than outside the puerperium (Kendell et al 1987; Munk-Olsen et al 2006).

Numerous scales have been developed for identifying postpartum depression or risk factors for the development of postpartum depression (Beck 1995; Ferguson et al 2002; Morris-Ruth et al 2003; Perfetti et al 2004; Austin et al 2005). The EPDS has emerged as a well-validated and widely-utilized instrument for postpartum depression screening and detection. Conversely, validated tools to assess depression during pregnancy are lacking (Gaynes et al 2005). By default, the EPDS, developed for postpartum use, has been increasingly used to identify depression during pregnancy (Adouard et al 2005; Thoppil et al 2005; Felice et al 2006) and to screen for those at risk for developing depression during pregnancy (Evans et al 2001; Rubertsson et al 2005; Gordon et al 2006). Beyond this ad hoc use of the EPDS, no scale exists to identify major depressive disorder during pregnancy. Moreover, only one screening test, an unvalidated scale consisting of only two items, has been developed specifically for depression in pregnancy (Campagne 2004). Our group in collaboration (Altshuler et al 2008), recently completed an individual item analysis of the 28 item Hamilton Rating Scale for Depression (HRSD) compared to SCID Mood Module to identify the items most predictive of an accurate identification of an episode of major depression across all trimesters of pregnancy. The seven items most predictive of the presence of depression were tested as a screening tool for depression during pregnancy (Altshuler et al 2008).

The urgent need to identify reliable instruments for detecting perinatal depression is underscored by: 1) numerous reports of adverse obstetrical, neonatal, and developmental outcomes in association with maternal stress, depressive symptoms, and episodes of major depression during the perinatal period (Paton et al 1977; Zuckerman & Bresnahan 1991; Sheer et al 1992; Hedegaard et al 1993; Pritchard & Teo 1994; Orr & Miller 1995; Chung et al 2001; Andersson et al 2004; Mancuso et al 2004; Dayan et al 2006; Diego et al 2006; Neggers et al 2006); 2) accurate diagnosis of a MDE during the peripartum is complicated by the fact that purportedly normal perinatal symptoms (e.g., fatigue, sleep disturbance, appetite and weight changes, diminished libido) potentially overlap with the neurovegetative symptoms comprising part of the diagnostic criteria for major depression; 3) lower estimates of maternal mental illness during pregnancy may be in part secondary to limited recognition (Vesga-Lopez et al 2008); and 4) validated assessment tools are a requisite step in the design and completion of much needed controlled treatment studies during the perinatal period.

The overall aim of the current study was to provide clinicians and researchers alike with information regarding the sensitivity and specificity of commonly used depression rating scales during pregnancy and the postpartum period. The specific objectives of the study were: 1) to identify optimal cutpoints (maximizing the summation of sensitivity and specificity) for commonly used depression rating scales during each trimester of pregnancy and the postpartum period; 2) to determine whether previous pregnancy and childbirth experience influences the performance of the rating instruments; and 3) to determine whether repeated administration of a depression rating scale over the course of pregnancy and the postpartum period is associated with learning effects that alter the optimal cutpoints for the rating scales. With respect to these objectives, our a priori hypotheses were: 1) that the performance of the scales including optimal cutpoints would be altered during pregnancy, particularly during the third trimester when many of the physical symptoms of pregnancy most closely mirror the neurovegetative symptoms of depression; 2) that multigravid women (having previously experienced the physical sequelae of gestation) would be more likely to report physical symptoms of depression on a depression rating scale than primigravid women producing higher cutpoints on the scales during pregnancy; and 3) that optimal cutpoint scores would be impacted by repeated administration of both clinician-administered and self-rated depression scales.

METHODS

Subjects

The study was conducted at the Women’s Mental Health Program (WMHP) at the Emory University School of Medicine. Women with a lifetime history of mental illness participating in one of two prospective longitudinal perinatal investigations of the pharmacokinetics of psychotropic medications and/or maternal stress (P50 MH 68036; P50 MH 77928) were screened for inclusion in the current analysis. The schedule and methods for assessing maternal depression were identical in the two studies. Participants were enrolled no later than week 28 of gestation and evaluated at 4–6 week intervals across pregnancy and through 26 weeks postpartum. At each visit, subjects completed the self-rated BDI and EPDS. In addition, a research interviewer masked to treatment status administered the Structured Interview Guide (Williams 1988) for the Hamilton Rating Scale for Depression (Hamilton 1960) to obtain 17-item (HRSD17) and 21-item (HRSD21) scores and the Mood Module of the Structured Clinical Interview for DSM-IV Axis I Disorders (First et al 2002). To ensure consistent administration of the clinician-rated instruments, research interviewers were trained to use a “rate as you see” approach when scoring items, eschewing any subjective judgment as to whether symptoms were due to depression or pregnancy/postpartum. Quarterly inter-rater reliability assessments were conducted throughout the course of both investigations to ensure maintenance of kappa statistics ≥ 0.8 on all clinician-administered instruments. All scales were coded with a HIPAA compliant identifier and entered into a centralized database. Subjects were included in the current analysis if they had two or more perinatal visits during which the SCID Mood Module and one or more of the depression rating scales were completed. The investigation was carried out in accordance with the latest version of the Declaration of Helsinki. The study was reviewed and approved by the Emory University Institutional Review Board. Informed consent of the participants was obtained after the nature of the procedures had been fully explained.

Data Analysis

Each visit was assigned to one of 6 distinct perinatal epochs including: 1) preconception; 2) 1st trimester (0–12 weeks gestation); 3) 2nd trimester (13–24 weeks gestation); 4) 3rd trimester (25 weeks gestation to delivery); 5) early postpartum (0–6 weeks); and 6) late postpartum (7–26 weeks). A completed SCID Mood Module plus one or more of the depression symptom scales was necessary for a visit to qualify for inclusion. At each visit, the presence (or absence) of a MDE was determined by the SCID Mood Module.

To assess the diagnostic accuracy of the symptom scales within each perinatal epoch and the overall perinatal period, the receiver operating characteristic curve (ROC) analysis proposed by Obuchowski (1997), which accounts for correlation due to repeatedly measured rating scales from each subject, was used. Defining a cutpoint score for a scale as the score such that greater or equal scores are considered consistent with the presence of a MDE, then the optimal cutpoint score for each scale was defined as the score at which the sum of the scale’s sensitivity and specificity was maximized within each perinatal epoch. Stratified ROC analyses were conducted to examine the impact of primigravid vs. multigravid pregnancies and first visit vs. follow-up visits on the accuracy of depression scales for identifying an active MDE. Typically, the diagnostic accuracy of a symptom scale is considered poor when ROC AUC < 0.70, fair when 0.70 ≤ ROC AUC < 0.80, good when 0.80 ≤ ROC AUC < 0.90, and excellent when 0.90 ≤ ROC AUC (Tape 2008). Wald tests were used to compare ROC AUCs. All statistical tests were two-tailed and conducted at a significance level of 0.05.

RESULTS

Analysis of Overall Sample

A total of 708 women were enrolled in longitudinal perinatal investigations of the pharmacokinetics of psychotropic medications and/or maternal stress. One hundred and seventy four women were excluded secondary to missing data – most commonly, lack of adequate follow-up visit data. Table 1 summarizes the characteristics of the entire study population, the subpopulation included in the analysis and the subpopulation excluded from the analysis due to missing data. The included group is demographically more diverse than the excluded group; specifically, the included group has higher minority representation, includes more unmarried subjects, has more subjects who have completed no more than a high school education, and has a higher proportion of unplanned pregnancies.

Table 1.

Demographics for the Entire Population, the Subpopulation Included in the Analysis and the Subpopulation Excluded from the Analysis

Characteristic All Enrollees (n=708) Included in Analysis (n=534) Excluded Group (n=174) P-valuea
Age (years) 33.3 (SD=5.0) 33.1(SD=5.1) 34.0(SD=4.6) 0.03
Gravidity 682b 519 163 0.29
 1 217(31.8%) 157(30.3%) 60(36.8%)
 2 222(32.6%) 174(33.5%) 48(29.5%)
 3 121(17.7%) 90(17.3%) 31(19.0%)
 ≥ 4 122(17.9%) 98(18.9%) 24(14.7%)
Race 707 534 173 0.04
 Asian 15(2.1%) 12(2.3%) 3(1.7%)
 Black/African Am. 56(7.9%) 51(9.6%) 5(2.9%)
 Multi-racial 1(0.1%) 1(0.2%) 0(0.0%)
 Native American 16(2.3%) 12(2.3%) 4(2.3%)
 White/Caucasian 619(87.4%) 458(85.8%) 161(93.1%)
Ethnicity 708 534 174 0.77
 Hispanic 22(3.1%) 16(3%) 6(3.5%)
 Non-Hispanic 686(96.9%) 518(97%) 168(96.5%)
Marital Status 708 534 174 0.02
 Divorced 22(3.1%) 19(3.6%) 3(1.7%)
 Married 619(87.4%) 456(85.4%) 163(93.7%)
 Never Married 38(5.4%) 32(6.0%) 6(3.5%)
 Unmarried/cohabitating 19(2.7%) 18(3.4%) 1(0.6%)
 Separated 9(1.3%) 9(1.7%) 0(0%)
 Widowed 1(0.1%) 0(0.0%) 1(0.6%)
Times Married 689 518 171 0.26
 0 56(8.1%) 48(9.3%) 8(4.7%)
 1 548(79.5%) 404(78.0%) 144(84.2%)
 2 72(10.5%) 57(11.0%) 15(8.8%)
 3 11(1.6%) 8(1.5%) 3(1.8%)
 4 2(0.3%) 1(0.2%) 1(0.6%)
Education 697 525 172 0.01
 ≤ High School 44(6.3%) 42(8.0%) 2(1.2%)
 ≤ College 403(57.8%) 301(57.3%) 102(59.3%)
 ≤ Graduate School 250(35.9%) 182(34.7%) 68(39.5%)
Pregnancy Planned 586 478 108 <0.0001
 Yes 422(72.0%) 325(68.9%) 97(89.8%)
 No 164(28.0%) 153(32.0%) 11(10.2%)
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a

P-values are for comparisons between subpopulations included and excluded in analysis.

b

Bold numbers are sample sizes of available data for each baseline variable. Due to sporadic missing data, available sample sizes vary for gravidity, race, times married, education

Five hundred and thirty four participants (75.4% of all enrollees), encompassing 640 pregnancies with 4025 visits, were included in the current analysis. The sample was very homogeneous: 33.1± 5.1 years of age, predominately Caucasian (85.8%), married or cohabitating at study entry (85.4%), and with a high school education or greater (92.0%). Because the gestational age at study entry varied (preconception through ≤ 28 weeks), the number of subjectswithin each perinatal epoch varied..

ROC analysis demonstrated that all symptom scales (BDI, EPDS, HRSD17, HRSD21) were highly predictive of MDE (cf. Table 2). The ROC AUCs, ranging from 0.855 to 0.971, were all statistically significant (p<0.0001). For all 4 scales, the peak ROC AUC was observed during the preconception period. As hypothesized, the ROC AUC was lowest during the third trimester for the BDI, HRSD17, and HRSD21. The AUC was lowest for the EPDS during the early postpartum. ROC AUCs for the EPDS suggest that it achieved excellent diagnostic validity (i.e., AUC ≥ 0.90) in 3 of the 6 epochs. The BDI achieved excellent diagnostic validity in 2 of 6 epochs, and the two HRSD scores each achieved excellent diagnostic validity in 1 of 6 epochs. The remainder of the AUCs for all 4 scales in all epochs were in the good range (0.80 ≤ AUC < 0.90). The EPDS (preconception, first trimester, third trimester) and BDI (second trimester, early postpartum, late postpartum) each achieved the largest ROC AUC among all scales in 3 of the 6 epochs.

Table 2.

Performance of Depression Rating Scales across Perinatal Epochs (n=4025 observations)

Rating Scale Epocha SCID MDE Criteria
 AUC of ROC Optimal Cut-pointb Sensitivity & Specificity
Yes No Total Sens. Spec.
HRSD17 PC 28 265 0.908 15 1.723 0.821 0.902
T1 72 446 0.881 14 1.597 0.819 0.778
T2 142 860 0.884 15 1.634 0.782 0.852
T3 81 706 0.857 15 1.579 0.741 0.839
PP-E 42 341 0.861 14 1.619 0.810 0.809
PP-L 115 878 0.877 14 1.618 0.774 0.844
Overall 480 3496 0.877 14 1.614 0.806 0.807
HRSD21 PC 28 264 0.908 16 1.759 0.857 0.902
T1 72 441 0.873 15 1.597 0.806 0.791
T2 141 852 0.884 15 1.629 0.823 0.806
T3 81 705 0.858 16 1.578 0.741 0.837
PP-E 42 341 0.857 14 1.566 0.810 0.757
PP-L 115 877 0.874 14 1.602 0.809 0.794
Overall 479 3480 0.875 15 1.603 0.789 0.814
BDI PC 28 256 0.938 17 1.780 0.893 0.887
T1 65 403 0.896 15 1.683 0.877 0.806
T2 114 780 0.906 13 1.686 0.904 0.782
T3 66 613 0.871 12 1.587 0.833 0.754
PP-E 32 294 0.898 14 1.615 0.813 0.803
PP-L 99 759 0.883 14 1.649 0.828 0.821
Overall 404 3105 0.895 13 1.648 0.866 0.782
EPDS PC 7 67 0.971 18 1.842 0.857 0.985
T1 24 132 0.912 12 1.644 0.833 0.811
T2 39 246 0.883 9 1.571 0.872 0.699
T3 6 138 0.949 15 1.797 0.833 0.964
PP-E 24 167 0.855 11 1.606 0.833 0.772
PP-L 50 447 0.864 12 1.606 0.760 0.846
Overall 150 1197 0.884 11 1.604 0.813 0.791
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a

Perinatal Epochs: PC=preconception; T1=first trimester; T2=second trimester; T3=third trimester; PP-E=early postpartum; PP-L=late postpartum

b

Optimal Cutpoint: The cutpoint is the score such that greater or equal scores are considered consistent with the presence of a major depressive episode. The optimal cutpoint is the cutpoint score that maximizes the sum of sensitivity and specificity.

To compare AUCs within each epoch, the analysis was also conducted using “complete cases” only, i.e., limited to visits in which all four depression scales were completed, and the results were similar. During the 2nd trimester, BDI had the largest AUC (0.908), which was significantly larger (p=0.02) than the smallest AUC (0.852, of HRSD17). For other epochs, there was no such significant difference between the largest and smallest AUC (data not shown).

Despite the consistently good to excellent diagnostic validity of all four scales across the 6 epochs, there was considerable variability in the optimal cutpoint scores for the self-rated instruments. The EPDS produced the greatest variation with the optimal cutpoint ranging from a low of 9 during the second trimester to a peak of 18 during preconception. Optimal cutpoints for the BDI ranged from a low of 12 during the third trimester to a high of 17 during preconception. Optimal cutpoints for the HRSD17 varied by only 1 point (from 14 to 15) and for the HRSD21 by only 2 points (from 14 to 16). Interestingly, the optimal cutpoint scores were highest during the preconception period for all four scales.

Primigravid vs. Multigravid Pregnancies

As noted above, there were 640 pregnancies completed by the 534 subjects included in the current analysis. Among these 640 pregnancies, there were 161 primigravid pregnancies, 465 multigravid pregnancies and 14 pregnancies with missing gravidity/parity data. Demographic analysis indicates that the primigravid group was younger (31.5 vs. 34.4 years, p<.0001) and less likely to be married (80.1% vs. 89.5%, p=.0006) than the multigravid group. There were no other significant demographic differences between the groups (data not shown).

For all four depression scales, across all pregnancy stages, the overall ROC AUC, optimal cutpoint, and summation of sensitivity and specificity for primigravid pregnancies is very similar to that observed for multigravid pregnancies, suggesting that gravidity status had no discernible impact of the global performance of the scales (cf. Table 3). However, inspection of the third trimester results demonstrates that cutpoints are higher for multigravid pregnancies for all 4 scales. In addition, the sensitivity of the scales corresponding to the optimal cutpoint is lower for multigravidas than primigravidas during the third trimester for all scales but the EPDS. Furthermore, within the multigravid group, the sensitivity of the HRSD17, HRSD21, and BDI at the optimal cutpoints reaches its nadir during the third trimester.

Table 3.

Comparative Performance of Depression Rating Scales in Primigravid vs. Multigravid Pregnancies

Rating Scale Epocha Primigravid Pregnancies (n=161)
 Multigravid Pregnancies (n=465)
SCID MDE Criteria AUC of ROC Optimal Cut-pointb Sensitivity & Specificity SCID MDE Criteria AUC of ROC Optimal Cut- pointb Sensitivity & Specificity
Yes No Total Sens. Spec. Yes No Total Sens. Spec.
HRSD17 PC 7 79 0.978 14 1.899 1.000 0.899 21 186 0.886 16 1.687 0.762 0.925
T1 20 121 0.860 12 1.628 0.950 0.678 51 317 0.887 15 1.624 0.804 0.820
T2 24 242 0.881 14 1.660 0.833 0.826 116 599 0.881 15 1.643 0.802 0.841
T3 10 177 0.882 13 1.668 0.900 0.768 67 517 0.843 15 1.557 0.731 0.826
PP-E 8 84 0.861 17 1.702 0.750 0.952 34 251 0.857 14 1.608 0.824 0.785
PP-L 21 219 0.926 12 1.727 0.905 0.822 92 635 0.861 14 1.595 0.772 0.824
Overall 90 922 0.896 12 1.655 0.900 0.755 381 2505 0.868 14 1.598 0.806 0.792
HRSD21 PC 7 78 0.978 16 1.885 1.000 0.885 21 186 0.882 16 1.718 0.810 0.909
T1 20 119 0.849 13 1.656 0.950 0.706 51 314 0.880 16 1.622 0.804 0.818
T2 24 242 0.885 15 1.651 0.792 0.860 115 591 0.880 16 1.620 0.783 0.838
T3 10 177 0.878 11 1.689 1.000 0.689 67 516 0.845 17 1.559 0.687 0.872
PP-E 8 84 0.886 17 1.667 0.750 0.917 34 251 0.849 13 1.570 0.853 0.717
PP-L 21 219 0.921 12 1.729 0.952 0.776 92 635 0.860 14 1.579 0.804 0.775
Overall 90 919 0.895 15 1.637 0.778 0.860 380 2493 0.867 16 1.587 0.747 0.840
BDI PC 7 78 0.964 20 1.936 1.000 0.936 21 178 0.928 17 1.750 0.857 0.893
T1 18 108 0.889 13 1.704 0.944 0.759 46 290 0.900 14 1.682 0.913 0.769
T2 20 224 0.888 13 1.671 0.850 0.821 93 543 0.906 13 1.676 0.914 0.762
T3 9 159 0.933 12 1.786 1.000 0.786 57 443 0.854 14 1.552 0.737 0.815
PP-E 6 75 0.820 10 1.680 1.000 0.680 26 214 0.916 15 1.707 0.885 0.822
PP-L 15 200 0.906 12 1.692 0.867 0.825 83 539 0.873 15 1.640 0.807 0.833
Overall 75 844 0.902 12 1.675 0.893 0.782 326 2207 0.890 13 1.637 0.871 0.766
EPDS PC 1 13 0.769 12 1.769 1.000 0.769 6 54 0.998 18 1.981 1.000 0.981
T1 6 33 0.932 9 1.758 1.000 0.758 18 98 0.912 13 1.635 0.778 0.857
T2 10 79 0.908 11 1.635 0.800 0.835 29 167 0.871 9 1.561 0.897 0.665
T3 1 38 0.737 9 1.711 1.000 0.711 5 99 0.988 15 1.970 1.000 0.970
PP-E 3 41 0.890 11 1.732 1.000 0.732 21 123 0.850 11 1.598 0.810 0.789
PP-L 8 127 0.848 13 1.781 0.875 0.906 42 309 0.863 11 1.568 0.762 0.806
Overall 29 331 0.884 11 1.649 0.828 0.822 121 850 0.883 11 1.591 0.810 0.781
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a

Perinatal Epochs: PC=preconception; T1=first trimester; T2=second trimester; T3=third trimester; PP-E=early postpartum; PP-L=late postpartum

b

Optimal Cutpoint: The cutpoint is the score such that greater or equal scores are considered consistent with the presence of a major depressive episode. The optimal cutpoint is the cutpoint score that maximizes the sum of sensitivity and specificity.

Comparison of First Visit vs. Follow-Up Visits

Among the 534 subjects included in the current analysis, 178 subjects had previously participated in other WMHP studies, and 356 completed their first research encounter at the WMHP during the current study. The comparison of first versus follow-up visits is limited to these 356 participants who completed 356 first visits and 2474 follow-up visits. Because all subjects were enrolled prior to 28 weeks gestation, none of the first visits occurred during the postpartum period. Consequently, the postpartum epochs were also excluded from the subsequent visits stratum to eliminate any confounding effect of the disparate perinatal epoch. There were no significant demographic differences between the 356 subjects included in this phase of the analysis and the 178 excluded except that the inclusion group was less likely to be Caucasian (83.2% vs. 91.0%, p= .004), reflecting the growing minority participation in WMHP research in recent years; and that the inclusion group was less likely to have a planned pregnancy (63.7% vs. 77.3%, p=.003).

ROC analysis indicated that all 4 scales performed in the good to excellent range at both initial visits and follow-up visits (cf. Table 4). The summation of sensitivity and specificity for all 4 scales was also consistent across the perinatal epochs within both strata. However, the optimal cutpoints for the HRSD17 and HRSD21 were very consistent between first and follow-up visits, whereas optimal cutpoints on the self-report instruments were generally 4–6 points higher for the first visit than for the follow-up visits during each perinatal epoch (cf. Table 4) and across PC, T1, T2 and T3 periods (cf. Table 4).

Table 4.

Comparative Performance of Depression Rating Scales at First Visit vs. Subsequent Visits

Rating Scale Epocha First Visits (n=356)
 Subsequent Visits (n=2474)
SCID MDE Criteria AUC of ROC Optimal Cut-pointb Sensitivity & Specificity SCID MDE Criteria AUC of ROC Optimal Cut-pointb Sensitivity & Specificity
Yes No Total Sens. Spec. Yes No Total Sens. Spec.
HRSD17 PC 6 51 0.851 15 1.696 0.833 0.863 10 150 0.990 16 1.947 1.000 0.947
T1 38 84 0.862 15 1.630 0.868 0.762 20 201 0.849 14 1.551 0.750 0.801
T2 52 80 0.880 15 1.629 0.904 0.725 67 465 0.857 14 1.570 0.761 0.809
T3 21 21 0.861 15 1.571 0.905 0.667 42 403 0.847 13 1.575 0.833 0.742
Overall 117 236 0.877 15 1.648 0.889 0.759 139 1219 0.866 14 1.595 0.784 0.811
HRSD21 PC 6 50 0.832 15 1.693 0.833 0.860 10 150 0.986 17 1.960 1.000 0.960
T1 38 83 0.856 16 1.599 0.816 0.783 20 200 0.843 13 1.575 0.850 0.725
T2 52 79 0.886 17 1.630 0.808 0.823 67 461 0.856 15 1.579 0.761 0.818
T3 21 20 0.856 22 1.614 0.714 0.900 42 403 0.846 16 1.587 0.738 0.849
Overall 117 232 0.876 15 1.610 0.889 0.721 139 1214 0.864 15 1.592 0.770 0.822
BDI PC 6 46 0.846 12 1.652 1.000 0.652 10 148 0.982 17 1.932 1.000 0.932
T1 33 72 0.877 18 1.654 0.848 0.806 19 187 0.871 15 1.666 0.842 0.824
T2 42 68 0.866 19 1.626 0.714 0.912 58 423 0.901 13 1.683 0.879 0.804
T3 17 17 0.824 12 1.588 0.941 0.647 34 353 0.857 12 1.566 0.824 0.742
Overall 98 203 0.871 19 1.587 0.735 0.852 121 1111 0.893 13 1.646 0.851 0.795
EPDS PC 0 8 NAc NA NA NA NA 6 49 0.998 16 1.980 1.000 0.980
T1 11 20 0.868 17 1.636 0.636 1.000 10 73 0.928 13 1.690 0.800 0.890
T2 12 23 0.873 17 1.580 0.667 0.913 23 165 0.860 6 1.533 1.000 0.533
T3 0 1 NA NA NA NA NA 6 101 0.959 15 1.814 0.833 0.980
Overall 23 52 0.849 17 1.614 0.652 0.962 45 388 0.907 13 1.623 0.733 0.889
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a

Perinatal Epochs: PC=preconception; T1=first trimester; T2=second trimester; T3=third trimester

b

Optimal Cutpoint: The cutpoint is the score such that greater or equal scores are considered consistent with the presence of a major depressive episode. The optimal cutpoint is the cutpoint score that maximizes the sum of sensitivity and specificity.

c

Not applicable when the number of subjects satisfying MDE criteria is 0.

DISCUSSION

It is reassuring that ROC analysis across all phases of the analysis indicates that all 4 instruments consistently performed in the good to excellent range (Tape 2008). The overall optimal cutpoints for each scale are consistent with previous reports. Moreover, the sensitivities and specificities of the 4 instruments were also very similar. It might, therefore, be inferred that any of the 4 depression rating scales evaluated in the current study are suitable candidates to identify episodes of major depression during pregnancy and the postpartum period. Given the ease of administration of self-report measures in both the clinical and research settings, it could be argued that there is no justification for using the labor intensive HRSD over the self-report BDI and EPDS. However, the stability of the cutpoint is a key consideration when screening a broad perinatal sample and conducting longitudinal follow-up. The clinician administered HRSD provided more stable cutpoints (1–2 point range) across the perinatal epochs compared to the BDI (5 point range) and EPDS (9 point range). Consequently, the present data suggests that the HRSD may be preferred when conducting longitudinal studies across pregnancy and the postpartum period, but the less costly BDI and EPDS may be preferred for cross-sectional studies.

Consistent with our previous experience (Altshuler et al 2008), the comparative performance of the HRSD17 and HRSD21 indicates that items 18–21 can be eliminated from the perinatal administration of the HRSD with little or no impact on the performance of the scale. Inclusion of items 18–21 elevated the optimal cutpoint within each perinatal epoch by only 0–1 points and produced no significant improvement in the ROC AUC, sensitivity, or specificity of the HRSD during pregnancy and the postpartum period.

It is noteworthy that the specificities of the scales were uniformly lower during pregnancy and the early postpartum period than during the preconception epoch. Late postpartum specificities were generally intermediate between preconception and pregnancy/early postpartum values. Consistent with our a priori hypothesis, we suspect this may be a consequence of the overlap between physical symptoms of pregnancy and the neurovegetative symptoms of depression. In contrast, we had anticipated that the symptomatic overlap of pregnancy and depression would elevate the optimal cutpoints during pregnancy, the current results found the pregnancy cutpoints to be the same as or lower than the preconception cutpoints. This suggests that women incorporate their own opinions regarding the etiology of the symptoms during both interview and completion of self-rated scales. An extended item analysis may clarify the role that the neurovegetative symptom items play in the perinatal performance of these rating scales.

The primigravida versus multigravida comparison provides additional insights on this issue. As noted above, there is no evidence from the current study to indicate that the gravidity status alters the overall performance of these scales across the entirety of pregnancy and the postpartum period; however, the current data does suggest that multigravidas rate the instruments differently during the third trimester. Whereas there was no evident difference in the specificity of the scales in the third trimester, the cutpoints are consistently higher among multigravidas during the third trimester, and the scale sensitivity is lower among multigravidas for 3 of the 4 scales. We suspect that this confluence of third trimester results among multigravidas (i.e., higher cutpoint, lower sensitivity, unchanged specificity) is a consequence of multigravidas being more ready to report physical discomforts, particularly when such symptoms are incongruent with prior pregnancies, on a depression rating scale than primigravidas. Inclusion of the physical symptoms by the multigravidas would tend to elevate the scores. With the higher overall scores, higher cutpoints would be needed to forestall, at least in part, the resultant decline in sensitivity.

Finally, the analysis of first visit versus follow-up visit performance of the scales is generally reassuring, but raises concerns regarding the lack of cutpoint stability of the self-report depression measures. Overall first visit versus follow-up visit cutpoints for the HRSD only varied by 0–1 points, but the BDI and EPDS first versus follow-up visit cutpoints differed by 6 and 4 points, respectively. This apparent post-first visit learning effect has significant implications for the use of these self-report depression rating scales in longitudinal studies across the perinatal period, again suggesting that the HRSD may be preferred for longitudinal investigations.

The study is limited by the homogeneous clinical population that was able to complete participation in a longitudinal investigation; thereby limiting the generalizability of these results to community based perinatal samples where self-rated instruments are likely to be employed as screening tools. Notably, the group of women excluded from the present analyses were more demographically homogeneous than the included group. While this counter-intuitive finding runs counter to most longitudinal studies, it may reflect the benefits garnered by study participants with respect to frequent contact providing additional education and support. Indeed, the greater heterogeneity of the inclusion group potentially enhances the generalizability of the study results and increases support for further research in perinatal maternal mental illness with respect to the benefit of repeated professional contact. Similarly, the study assesses the validity of multiple scales in identifying episodes of depression that fulfill SCID diagnostic criteria. Limiting to episodes meeting diagnostic criteria, fails to assess the utility of scales in appropriately identifying subsyndromal symptoms warranting clinical attention.

Investigations in perinatal psychiatry continue to refine more optimal study parameters and methodology. As noted in our previous investigation, retrospective maternal reports are inadequate proxies for categorizing maternal depression during pregnancy and exposure to non-psychotropic medications (Newport et al 2008). The current study sought to define optimal cutpoint scores and factors that influence these scores. All scales demonstrated good to excellent ROC AUCs in identification of a MDE as defined by SCID criteria across pregnancy and the postpartum period. The impact of gravidity, first visit completion versus follow up visits, and variability of optimal cutpoint scores across the perinatal period need to be considered in the application of these scales in future longitudinal and treatment investigations.

Footnotes

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