Table 3.

Incidence rate ratios (95% CI) predicting depression with social relationships, Swiss health survey, 2007

	Social relationship predictors individually		Adjusted for other social relationship variables		Further adjusted for sociodemographics		Loneliness omitted
	Major depression	Depressive symptoms	Major depression	Depressive symptoms	Major depression	Depressive symptoms	Major depression	Depressive symptoms
Loneliness
Never	Referent	-	-	-	-	-	-	-
Sometimes	3.40 (2.58, 4.48)	1.66 (1.58, 1.73)	2.94 (2.13, 4.05)	1.56 (1.49, 1.64)	2.68 (1.95, 3.68)	1.55 (1.48, 1.63)	-	-
Quite or very often	16.4 (12.4, 21.7)	3.12 (2.87, 3.38)	11.0 (7.28, 16.5)	2.58 (2.34, 2.85)	9.97 (6.84, 14.5)	2.39 (2.18, 2.63)	-	-
Confidant	0.44 (0.30, 0.65)	0.69 (0.64, 0.74)	0.82 (0.53, 1.27)	0.86 (0.79, 0.93)	0.75 (0.48, 1.18)	0.90 (0.82, 0.98)	0.59 (0.38, 0.92)	0.86 (0.79, 0.94)
Unmet support	2.74 (2.15, 3.51)	1.56 (1.49, 1.64)	1.41 (1.04, 1.90)	1.27 (1.20, 1.34)	1.40 (1.04, 1.88)	1.28 (1.21, 1.35)	2.11 (1.63, 2.73)	1.47 (1.39, 1.54)
Tangible support	0.38 (0.28, 0.53)	0.64 (0.60, 0.69)	0.77 (0.53, 1.11)	0.83 (0.77, 0.89)	0.76 (0.52, 1.12)	0.83 (0.77, 0.90)	0.58 (0.40, 0.84)	0.78 (0.72, 0.84)
Social contact
0-9	-	-	-	-	-	-	-	-
10-12	0.65 (0.45, 0.94)	0.82 (0.76, 0.89)	0.87 (0.59, 1.29)	0.91 (0.84, 0.98)	0.87 (0.58, 1.29)	0.92 (0.85, 0.99)	0.78 (0.54, 1.13)	0.90 (0.83, 0.98)
13-14	0.53 (0.37, 0.77)	0.77 (0.72, 0.83)	0.75 (0.50, 1.12)	0.88 (0.81, 0.95)	0.74 (0.48, 1.12)	0.90 (0.83, 0.97)	0.66 (0.44, 0.97)	0.87 (0.80, 0.95)
15-16	0.38 (0.25, 0.58)	0.70 (0.64, 0.75)	0.56 (0.35, 0.90)	0.81 (0.74, 0.88)	0.56 (0.34, 0.91)	0.83 (0.76, 0.91)	0.50 (0.31, 0.80)	0.81 (0.74, 0.89)
17-21	0.49 (0.30, 0.78)	0.69 (0.63, 0.75)	0.77 (0.47, 1.27)	0.81 (0.74, 0.88)	0.76 (0.45, 1.28)	0.81 (0.74, 0.89)	0.65 (0.39, 1.08)	0.78 (0.71, 0.86)
Married/cohabiting	0.56 (0.45, 0.71)	0.89 (0.85, 0.93)	0.80 (0.63, 1.02)	1.01 (0.96, 1.05)	0.75 (0.59, 0.95)	0.97 (0.92, 1.01)	0.56 (0.45, 0.71)	0.87 (0.82, 0.91)
Sociodemographics
Age
18-24					Referent	-	-	-
25-34					0.91 (0.54, 1.55)	1.03 (0.93, 1.15)	1.07 (0.63, 1.81)	1.07 (0.97, 1.20)
35-44					1.13 (0.67, 1.91)	1.04 (0.95, 1.15)	1.25 (0.74, 2.11)	1.08 (0.97, 1.19)
45-54					1.07 (0.62, 1.84)	1.08 (0.97, 1.20)	1.17 (0.68, 2.02)	1.10 (0.98, 1.23)
55-64					0.76 (0.44, 1.31)	1.11 (1.00, 1.24)	0.83 (0.48, 1.43)	1.12 (1.01, 1.25)
65+					0.32 (0.18, 0.60)	1.21 (1.09, 1.33)	0.31 (0.16. 0.58)	1.16 (1.05, 1.29)
Male gender					0.84 (0.66, 1.07)	0.91 (0.87, 0.95)	0.75 (0.58, 0.97)	0.88 (0.84, 0.92)
Education
Mandatory					Referent	-	-	-
Secondary					0.83 (0.59, 1.18)	0.97 (0.89, 1.05)	0.73 (0.51, 1.04)	0.93 (0.86, 1.01)
High school					0.77 (0.45, 1.32)	0.93 (0.83, 1.03)	0.64 (0.37, 1.10)	0.89 (0.79, 0.99)
University					0.86 (0.57, 1.30)	0.87 (0.79, 0.96)	0.73 (0.48, 1.12)	0.83 (0.75, 0.91)
Regional language
German					Referent	-	-	-
French					0.99 (0.78, 1.27)	1.32 (1.26, 1.39)	1.09 (0.85, 1.40)	1.35 (1.28, 1.41)
Italian					0.98 (0.66, 1.45)	1.22 (1.12, 1.33)	1.10 (0.73, 1.65)	1.26 (1.15, 1.37)
Nationality
Swiss					Referent	-	-	-
Italian					1.28 (0.75, 2.21)	1.25 (1.05, 1.49)	1.45 (0.80, 2.62)	1.28 (1.07, 1.52)
Other					1.09 (0.75, 1.58)	1.01 (0.94, 1.09)	1.05 (0.73, 1.52)	1.01 (0.93, 1.09)

Twelve-month major depression was assessed with the Composite International Diagnostic Interview (CIDI) short form [38]. Depressive symptoms experienced over the last two weeks were assessed with the Depression Screening Questionnaire [39]. Incidence rate ratios for major depressive disorder were estimated using Poisson regression with robust standard errors [44]. Incidence rate ratios for depressive symptoms were estimated using negative binomial regression. Confidence intervals (CI) that do not include 1.0 are statistically significant at p < = 0.05 and are in bold. Confidant and tangible support variables have three levels but have been scaled to 0, 0.5, 1.0 in order to increase comparability with binary predictors. CI = confidence interval.