Validation of the Zung self-rating depression scale (SDS) in older adults

Figures & data

Table 1. Characteristics of the study population (N = 520).

		Based on M.I.N.I.		p
	Total	Non-depressed	Depressed
	n	n (%)	n (%)
Total	520	493 (94.8%)	27 (5.2%)
Gender				.111
Male	211	204 (96.7%)	7 (3.3%)
Female	309	289 (93.5%)	20 (6.5%)
Marital status				.703
Married/Cohabit	343	328 (95.6%)	15 (4.4%)
Single	24	23 (95.8%)	1 (4.2%)
Widower/Widow	129	121 (93.8%)	8 (6.2%)
MMSE, mean (std)	26.6 (2.3)	26.6 (2.3)	26.8 (2.1)	.603
Missing data	7 (1.4%)	5 (1.0%)	2 (7.4%)	.046^a exact
Any chronic diseases				.965
No	37	35 (94.6%)	2 (5.4%)
Yes	420	398 (94.8%)	22 (5.2%)
Zung’ score
Total	34.9 (7.7)	34.3 (7.2)	45.6 (8.0)	<.001
Missing data	18 (3.5%)	15 (3.0%)	3 (11.1%)	.060^a exact
Negative symptoms	12.9 (2.9)	12.7 (2.6)	17.2 (3.4)	<.001
Positive symptoms	16.7 (5.0)	16.3 (4.8)	22.6 (4.4)	<.001
Somatic symptoms	5.3 (1.6)	5.2 (1.6)	5.8 (1.8)	.104
BDI-21	7.2 (5.7)	6.6 (5.1)	16.6 (6.9)	<.001
Missing data	46 (8.9%)	44 (8.9%)	2 (7.4%)	1.000^a exact

BDI-21: 21-item Beck Depression Inventory; M.I.N.I.: Mini Neuropsychiatric Interview; MMSE: Mini-Mental State Examination.

^at-test, Chi-Square test or as appropriate Fisher’s Exact test.

Table 2. Screening parameters of the SDS for detecting current major depression based on Mini Neuropsychiatric Interview (M.I.N.I.) results.

	Zung self-rating depression Scale, cut-off points
	≥39		≥40
Current major depression	Positive	Negative	Positive	Negative
Yes	19	5	18	6
No	133	345	119	359
Sensitivity	79.2 (57.8–92.9)		75 (53.3–90.2)
Specificity	72.2 (67.9–76.1)		75.1 (71–78.9)
AUC	0.76 (0.67–0.84)		0.75 (0.66–0.84)
Youden's index	0.51		0.50
Likelihood ratio (+)	2.85 (2.21–3.66)		3.01 (2.28–3.98)
Likelihood ratio (−)	0.29 (0.13–0.63)		0.33 (0.17–0.67)
Odds ratio	9.86 (3.73–26)		9.05 (3.61–22.6)
Positive predictive value	12.5 (7.7–18.8)		13.1 (7.98–20)
Negative predictive value	98.6 (96.7–99.5)		98.4 (96.5–99.4)

Figure 1. Receiver operating characteristics (ROC) curves for the BDI-21 and SDS.