Stressful social relations and mortality: A prospective cohort study

Abstract

Few studies have examined the relationship between stressful social relations in private life and all-cause mortality.
To evaluate the association between stressful social relations (with partner, children, other family, friends and neighbours, respectively) and all-cause mortality in a large population-based study of middle-aged men and women. Further, to investigate the possible modification of this association by labour force participation and gender.
We used baseline data (2000) from The Danish Longitudinal Study on Work, Unemployment and Health, including 9875 men and women aged 36-52 years, linked to the Danish Cause of Death Registry for information on all-cause mortality until 31 December 2011. Associations between stressful social relations with partner, children, other family, friends and neighbours, respectively, and all-cause mortality were examined using Cox proportional hazards models adjusted for age, gender, cohabitation status, occupational social class, hospitalisation with chronic disorder 1980-baseline, depressive symptoms and perceived emotional support. Modification by gender and labour force participation was investigated by an additive hazards model.
Frequent worries/demands from partner or children were associated with 50-100% increased mortality risk. Frequent conflicts with any type of social relation were associated with 2-3 times increased mortality risk. Interaction between labour force participation and worries/demands (462 additional cases per 100 000 person-years, p=0.05) and conflicts with partner (830 additional cases per 100 000 person-years, p<0.01) was suggested. Being male and experiencing frequent worries/demands from partner produced 135 extra cases per 100 000 person-years, p=0.05 due to interaction.
Stressful social relations are associated with increased mortality risk among middle-aged men and women for a variety of different social roles. Those outside the labour force and men seem especially vulnerable to exposure.

Full text

Stressful social relations and mortality:
a prospective cohort study
Rikke Lund,
1,2
Ulla Christensen,
1
Charlotte Juul Nilsson,
1,2
Margit Kriegbaum,
2,3
Naja Hulvej Rod
1
1
Section of Social Medicine,
Department of Public Health,
University of Copenhagen,
Copenhagen, Denmark
2
Center for Healthy Aging,
University of Copenhagen,
Denmark
3
Section of Health Services
Research, Department of Public
Health, University of
Copenhagen, Denmark
Correspondence to
Rikke Lund, Section of Social
Medicine, Department of
Public Health, University of
Copenhagen, Oster
Farimagsgade 5, Postbox
2099, DK-1014 Copenhagen
K, Denmark;
rilu@sund.ku.dk
Received 22 November 2013
Revised 6 February 2014
Accepted 10 March 2014
Published Online First
8 May 2014
To cite: Lund R,
Christensen U, Nilsson CJ,
et al.J Epidemiol
Community Health
2014;68:720–727.
ABSTRACT
Background Few studies have examined the
relationship between stressful social relations in private
life and all-cause mortality.
Objective To evaluate the association between stressful
social relations (with partner, children, other family,
friends and neighbours, respectively) and all-cause
mortality in a large population-based study of middle-
aged men and women. Further, to investigate the
possible modification of this association by labour force
participation and gender.
Methods We used baseline data (2000) from The
Danish Longitudinal Study on Work, Unemployment and
Health, including 9875 men and women aged 36–
52 years, linked to the Danish Cause of Death Registry for
information on all-cause mortality until 31 December
2011. Associations between stressful social relations with
partner, children, other family, friends and neighbours,
respectively, and all-cause mortality were examined using
Cox proportional hazards models adjusted for age,
gender, cohabitation status, occupational social class,
hospitalisation with chronic disorder 1980–baseline,
depressive symptoms and perceived emotional support.
Modification by gender and labour force participation was
investigated by an additive hazards model.
Results Frequent worries/demands from partner or
children were associated with 50–100% increased
mortality risk. Frequent conflicts with any type of social
relation were associated with 2–3 times increased
mortality risk. Interaction between labour force
participation and worries/demands (462 additional cases
per 100 000 person-years, p=0.05) and conflicts with
partner (830 additional cases per 100 000 person-years,
p<0.01) was suggested. Being male and experiencing
frequent worries/demands from partner produced 135
extra cases per 100 000 person-years, p=0.05 due to
interaction.
Conclusions Stressful social relations are associated
with increased mortality risk among middle-aged men
and women for a variety of different social roles. Those
outside the labour force and men seem especially
vulnerable to exposure.
INTRODUCTION
The health protective effects of social relations on
mortality risk are widely recognised and have been
contrasted with the effects on health of more well-
known risk factors for mortality, such as smoking,
alcohol intake and obesity.
12
However, social rela-
tions also have stressful aspects such as conflicts,
demands, insensitivity and worries, with potential
but less studied health damaging effects.
3–5
Stressful aspects of social relations have previously
been associated with physiological parameters
detrimental to health, such as dysregulation of
endocrine,
6
cardiovascular
78
and immune func-
tioning.
9
A higher risk of incident cardiovascular
disease (CVD) has also been found among those
who have conflicts or worries from social rela-
tions,
71011
but little is known about the relation-
ship with all-cause mortality.
5
In one of the few
studies examining this, no association between
adverse exchanges with the closest confidant and
risk of all-cause and CVD mortality was found.
12
Variabilities in social support, network size and
stressful social relations exist, with the lowest
support and highest levels of stress found in the
lower socioeconomic groups.
12 13
Furthermore, it
has been hypothesized that people lower in the
social hierarchy are particularly responsive to stres-
sors as formulated in the theory of differential vul-
nerability.
14 15
Differential vulnerability concerns
the differential effect of a given stressor across
social positions.
14 16
It is suggested that the
increased vulnerability of groups of lower socio-
economic position (SEP) is due to the lack of
health-promoting coping strategies among people
who have fewer socioeconomic and intrapsychic
(eg, self-esteem) and social resources, such as access
to guidance and support from others.
15 17
The
theory has been supported by previous
studies,
15 18–21
—for example, McLeod and Kessler
found higher social vulnerability towards several
types of major personal events such as income loss,
ill health, divorce and death of a loved one for
those disadvantaged by income, education and
occupational status.
19
However, little is known
about the differential effects of social relations on
health outcomes across SEP. In one of the few
studies (cross-sectional in design) to examine this,
the poorest self-reported health outcomes was
found among those in low SEP and with low social
integration (ie, few social contacts), partly support-
ing the differential vulnerability hypothesis.
22
These findings, however, remain to be replicated in
a longitudinal design. In addition, to the best of
our knowledge the interactive effect of SEP and
stressful social relations on mortality has not previ-
ously been studied.
Gender differences are also described, with men
generally having smaller and less diverse net-
works,
23 24
while women seem more likely to have
emotional support than men.
25
Little is known
about gender differences in stressful social rela-
tions. A previous study suggested that women have
higher levels of demands/worries and conflicts with
family and children than men, while no gender dif-
ferences in experience of worries/demands and
conflicts with partner were identified.
11
It has been
720 Lund R, et al.J Epidemiol Community Health 2014;68:720–727. doi:10.1136/jech-2013-203675
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suggested that women are more vulnerable to strain from the
family than men,
26
but other studies have not supported such
gender differences.
27
Gender differences in vulnerability to
social stressors may be driven by a combination of physiological,
psychological and behavioural components.
28
Women’s stronger
inclination to develop social support networks and their rela-
tively greater dependency on enduring relationships may make
them more vulnerable to life events or social stressors with
negative interpersonal consequences,
29
such as, for example, fre-
quent conflicts or demands/worries. Accordingly, greater vulner-
ability to stressors has been found among women when mental
health has been studied as the outcome.
30
On the other hand,
men exposed to stressors show greater reactivity to stress, as
measured by greater increases in cortisol, than women.
31
Such
gender differences in social roles and stress reactivity makes it
interesting to examine potential gender differences in the health
consequences of social relations.
5
The aim of this study was to evaluate the association between
stressful social relations (with partner, children, other family,
friends and neighbours, respectively) and all-cause mortality in a
large population-based study of middle-aged men and women.
Further, to investigate the possible modification of this associ-
ation by labour force participation and gender.
METHODS
In Spring 2000, 11 082 men and women aged either 40 or
50 years by 1 October 1999 were randomly selected from a
10% random sample of the Danish population (cohort 1). For
the same study, 4145 individuals aged 36–52 years who had
been receiving transfer income (due to unemployment, sickness
benefit or disability pension) for more than 70% of the time
during the 3 years before baseline in early Spring 2000 were
randomly selected from the Danish population (cohort 2). Of
these cohorts, 9875 completed a questionnaire (response rate:
69% (cohort 1) and 55% (cohort 2)). Five people were non-
traceable in the Danish registries, leaving 9870 for inclusion in
the study. Non-responders from both cohorts were more often
men, immigrants from the third world or the Balkans, and were
more often non-trained, semiskilled or unemployed. There was
no difference between responders and non-responders in their
contact with a general practitioner. The population has been
described in detail previously.
32
All individuals were linked to
the Nationwide Danish Cause of Death Registry using a unique
personal identification number for information on all-cause
mortality until 31 December 2011.
For each measure of stressful social relations a subsample was
constructed with complete information on the covariates
included. For example, respondents without a partner
(N=1490) were not included in the analysis of worries/demands
from partner. Across the subsamples, 4% had missing measures
of stressful social relations and 5% had missing information on
occupational social class. The subsample sizes varied between
7393 and 8708 people.
Measures of stressful social relations
Stressful social relations were measured by the following ques-
tions ‘In your everyday life, do you experience that any of the
following people demand too much of you or seriously worry
you?’and ‘In your everyday life, do you experience conflicts
with any of the following people?’with one item for each of
the following social roles: partner, children (your own or part-
ner’s), other family, friends and neighbours. The response key
was ‘always’,‘often’,‘sometimes’,‘seldom’,‘never’,‘have none’.
In the main effects analyses the variable was kept in all response
categories or the categories always/often were combined where
the number of cases was small (<5). ‘Seldom’was used as the
reference category. Being exposed to stressful social relations
‘always’or ‘often’was considered the high risk condition and
consequently, for the interaction analyses, the variables were
dichotomised into ‘always/often’versus ‘sometimes/seldom/
never’.
The questions about social relations included in this study
(Copenhagen Social Relations Questionnaire (CSRQ)) were
developed based on the recommendations by Glass et al
33
of
including several social roles. The instrument covers both struc-
tural (eg, contact frequency and diversity) and functional aspects
of social relations (eg, emotional support, instrumental support
and demands/worries and conflicts). Content validity of the
CSRQ was tested by focus group discussions and individual
interviews with 31 informants. Another 94 men and women
took part in an 8-day test–retest analysis. Informants generally
stated that the questions and response categories were relevant
and easy to understand. Furthermore, themes on the structure
of social relations, social support and, of special relevance to
this study, the stressful aspects of social relations, emerged
clearly from the template analysis of the interviews. The reliabil-
ity test showed moderate to excellent agreement for all items
concerning stressful social relations (κ=0.41–0.82). In general,
agreement was better for items dealing with the closest social
relations such as partner and children (κ=0.74–82).
34
In conclu-
sion, the CSRQ shows satisfactory content and face validity as
well as reliability and is suitable for measuring structure and
function of social relations, including the negative aspects.
34
Covariates
Potential confounders for the analyses were identified based on
prior knowledge and the method of directed acyclic graphs.
35
This method provides a graphical tool for identification and
selection of relevant confounders in epidemiological studies and
thereby reduces the risk of biased results. The selected covariates
included age, gender, occupational social class, cohabitation
status, prior hospitalisation with chronic physical and mental
disorders, depressive symptoms and emotional social support.
Baseline social class was measured by occupational position and
coded into classes I–V in accordance with the standards of the
Danish National Institute of Social Research, which is similar to
the British Registrar General’s Classification I–V. We added
social class VI representing people receiving transfer income,
and for the descriptive table the variable was recoded into the
following three categories: I–III (predominantly non-manual
occupations); IV–V (predominantly skilled and unskilled
manual occupations) and VI (transfer income due to unemploy-
ment, sickness leave or disability pension).
In the main effects analyses, the variable was included with all
its original six categories. For the interaction analyses this vari-
able was dichotomised into social classes I–V (employed) and
social class VI (transfer income). Baseline cohabitation status
was measured by the question: ‘Do you live alone?’, (yes/no).
Hospitalisation with chronic diseases (yes/no) was included as a
proxy for severe health problems before baseline. A participant’s
personal identification number was linked to the Danish
National Patient Registry for information on hospitalisation
between 1 January 1980 and 30 June 2000 with any of the fol-
lowing diagnoses of chronic diseases: cancer, diabetes, CVD,
chronic lung disease, chronic renal disease and mental disorders.
Depression was measured by the Major Depression Inventory
based on 12 items of depressive symptoms (score range 0–50),
which has been shown to have good validity.
36
We included
Lund R, et al.J Epidemiol Community Health 2014;68:720–727. doi:10.1136/jech-2013-203675 721
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baseline depressive symptoms as a continuous variable in the
multivariable analyses. In the descriptive analyses we categorised
depressive symptoms into no (0–2), mild (3–8), moderate (9–19)
and severe symptoms (20–50).
37
Perceived emotional support was measured by the following
question: ‘Can you talk with any of the following people, if you
need support?’, including one item for each of the following
social roles: partner, other family and friends. The response key
was ‘always’,‘often’,‘sometimes’,‘seldom’,‘never’,‘have none’.
A summary index indicating the number of roles in the close
(adult) social network who always/often provided emotional
support was developed for the role’s partner, other family,
friends; the index ranged from 0 to 3 for the number of social
roles from whom emotional support is expected ‘always’or
‘often’.
Depressive symptoms and emotional support may act both as
confounders and mediators for the relation between stressful
social relations and mortality and were consequently added to
separate models.
To examine the effects on mortality of the combination of
stress from partner and labour force participation new compos-
ite variables were created: (1) sometimes/seldom/never conflicts
with partner and employed (I–V)(reference group); (2) some-
times/seldom/never conflicts with partner and receiving transfer
income; (3) always/often conflicts with partner and employed;
(4) always/often conflicts with partner and receiving transfer
income. Similar variables were constructed for stress from
partner and gender. Women with low levels of stress from social
relations were used as the reference category.
Statistical analyses
Cox proportional hazards models with age as the underlying
time variable were used to analyse the data. All variables met
the proportional hazards assumption. Main effects of stressful
social relations on all-cause mortality were initially estimated by
HRs with 95% CIs. Model 1 included age and gender; model 2
was further adjusted for baseline occupational social class,
cohabitation status and hospitalisation with chronic diseases
before baseline; model 3 added depressive symptoms and model
4 further included perceived emotional support.
To assess the absolute associations of the combined variables
with mortality, we used the additive hazards model, which is a
flexible semiparametric model for survival outcomes.
38
In that
model, the hazard is modelled as a linear function of the
explanatory variables and the estimates can therefore be directly
interpreted as the number of additional cases associated with
the explanatory variables—that is, the extra cases that exceed
the combination of their individual effects. The underlying
assumption of age-invariant associations was tested and no indi-
cation of violation was identified except for the analyses includ-
ing worries/demands from partner where maximum follow-up
time was limited to 64 years of age. There is continuing discus-
sion about how to estimate interaction, but most health
researchers would agree that interventions or preventive strat-
egies should be aimed at those subgroups where most cases
could be prevented.
39
To identify such subgroups, deviation
from additivity of absolute effects is the relevant measure of
interest. When applying additive hazards models, the explana-
tory models are fitted to an additive scale, and product terms to
assess deviation from additivity can be included and used to dir-
ectly obtain the number of additional deaths due to interaction
between labour force participation and gender, on the one
hand, and stressful social relations, on the other.
40
Departure
from multiplicativity in the interaction analyses was tested by
including a product term between stressful social relations and
either gender or labour market attachment in separate models.
Table 1 Distribution of covariates by conflicts with partner (%), N=7401 in the Danish Longitudinal Study on Work Unemployment and Health
baseline 2000, Denmark
Covariates Always/often Sometimes Seldom Never χ
2
p value
Gender
Women 269 (7) 1155 (28) 1831 (45) 822 (20)
Men 182 (6) 896 (27) 1540 (46) 706 (21) 0.08
Occupational social class
I–III 198 (6) 970 (29) 1609 (48) 593 (18)
IV–V 132 (5) 717 (27) 1240 (46) 600 (22)
VI 121 (9) 364 (27) 522 (39) 335 (25) <0.0001
Living alone
No 414 (6) 1950 (28) 3231 (46) 1423 (20)
Yes 37 (10) 101 (26) 140 (37) 105 (27) <0.0001
Hospitalisation 1980–2000
No 415 (6) 1918 (28) 3177 (46) 1390 (20)
Yes 36 (7) 133 (27) 194 (39) 138 (28) 0.0002
Depressive symptoms
No 62 (2) 507 (19) 1345 (50) 771 (29)
Mild 170 (5) 1018 (32) 1490 (47) 524 (16)
Moderate 124 (12) 377 (36) 399 (38) 159 (15)
Severe 95 (21) 149 (33) 137 (30) 74 (16) <0.0001
Emotional support*
3 122 (3) 948 (23) 2075 (50) 1015 (24)
2 137 (8) 518 (32) 681 (42) 295 (18)
1 109 (8) 469 (36) 542 (41) 192 (15)
0 83 (28) 116 (39) 73 (25) 26 (9) <0.0001
*Number of people from whom emotional support is expected always/often.
722 Lund R, et al.J Epidemiol Community Health 2014;68:720–727. doi:10.1136/jech-2013-203675
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Additive hazards models were fitted using the software
package R (through the package ‘timereg’) and all other analyses
were conducted using PROC PHREG, SAS V.9.2
RESULTS
During 11 years of follow-up, 196 women (4%) and 226 men
(6%) died. The major causes of death were cancer (47%), CVD
(14%), liver disease due to alcohol abuse (8%) and violent
deaths (accidents, suicide) (7%). Nine per cent of the population
reported always/often experiencing demands/worries from their
partner, 10% from children, 6% from family and 2% from
friends. Six per cent of the population always or often experi-
enced conflicts with their partner, 6% with their children, 2%
with their family and 1% with friends. Table 1 shows the distri-
bution of conflicts with partner by covariates. Always or often
experiencing conflicts with their partner was associated with
lower occupational social class, with living alone, with higher
depressive symptoms and with lower access to emotional
support. These patterns were roughly similar across different
types of exposures—that is, demands/worries and conflicts with
other parts of the social network (data not shown).
Worries and demands
Those who ‘always’(HR=1.93; 95% CI 1.02 to 3.65) or
‘often’(HR=1.81; 1.23 to 2.67) experienced worries and
demands from partner had a higher mortality risk after adjust-
ment for gender, social class, cohabitation status and prior hos-
pitalisation than those who ‘seldom’had this experience
(P
trend =
0.002). Always and often experiencing worries and
demands from children was also associated with higher mortal-
ity risk (HR=1.55; 1.08 to 2.20), whereas worries and
demands from other family, friends and neighbours were not
(table 2).
Conflicts
Conflicts with any type of social relation were associated with
higher mortality risk (P
trend
=0.001–0.04), and those who always
or often experienced conflicts with their social relations were at
markedly higher risk of premature death (table 3). For example,
those who always or often experienced conflicts with their partner
(HR=2.19; 95% CI 1.49 to 3.21) or friends (HR=2.63; 1.16 to
5.93) or who always experienced conflicts with neighbours
(HR=3.07; 1.49 to 6.32) had higher mortality risk than those
who seldom had such conflicts (table 3).
Generally, adjustment for depressive symptoms and emotional
support at baseline only attenuated the associations slightly and
did not change the overall conclusions. These findings suggest
that none of these factors seem to strongly confound or mediate
the associations. ‘Never’experiencing social negativity from
social relations was associated with a slightly increased mortality
than those who ‘seldom’have this experience except for never
having conflicts with friends.
Modification by gender and labour force participation
Figure 1 shows the associations of the combined variable for
stressful relations with partner and labour market participation
Table 2 Demands/worries from social relations and all-cause mortality 2000–2011
Model 1 Model 2 Model 3 Model 4
Demands/worries Total No No of cases (%) HR 95% CI HR 95% CI HR 95% CI HR 95% CI
Partner (N=7393)
Always 128 11 (9) 2.54 1.36 to 4.77 1.93 1.02 to 3.65 1.73 0.91 to 3.29 1.73 0.91 to 3.29
Often 546 37 (7) 2.20 1.50 to 3.24 1.81 1.23 to 2.67 1.64 1.11 to 2.44 1.64 1.10 to 2.44
Sometimes 1550 66 (4) 1.44 1.05 to 1.99 1.32 0.95 to 1.82 1.25 0.91 to 1.73 1.25 0.90 to 1.73
Never 2504 104 (4) 1.16 0.87 to 1.55 1.05 0.79 to 1.40 1.08 0.81 to 1.44 1.08 0.81 to 1.44
Seldom 2665 86 (3) 1.00 1.00 1.00 1.00
Trend p value 0.002 0.02 0.02
Children (N=7856)
Always/often 794 44 (6) 1.76 1.24 to 2.51 1.55 1.08 to 2.20 1.39 0.97 to 2.00 1.40 0.97 to 2.00
Sometimes 2145 86 (4) 1.24 0.93 to 1.65 1.21 0.91 to 1.61 1.17 0.88 to 1.55 1.17 0.88 to 1.55
Never 2230 128 (6) 1.44 1.11 to 1.87 1.30 1.00 to 1.68 1.32 1.01 to 1.71 1.32 1.01 to 1.71
Seldom 2687 104 (4) 1.00 1.00 1.00 1.00
Other family (N=8708)
Always/often 545 28 (5) 1.22 0.82 to 1.83 0.96 0.64 to 1.44 0.89 0.59 to 1.34 0.89 0.59 to 1.34
Sometimes 1879 85 (5) 1.17 0.89 to 1.52 1.11 0.85 to 1.45 1.07 0.82 to 1.40 1.07 0.82 to 1.40
Never 3555 155 (4) 1.17 0.94 to 1.46 1.05 0.84 to 1.31 1.06 0.85 to 1.33 1.07 0.85 to 1.34
Seldom 2729 154 (6) 1.00 1.00 1.00 1.00
Friends (N=8654)
Always/often 139 9 (7) 1.47 0.75 to 2.87 1.10 0.56 to 2.15 0.96 0.49 to 1.89 0.96 0.49 to 1.89
Sometimes 936 48 (5) 1.26 0.92 to 1.74 1.07 0.77 to 1.47 1.03 0.74 to 1.42 1.03 0.74 to 1.42
Never 3710 185 (5) 1.02 0.83 to 1.25 1.01 0.82 to 1.24 1.03 0.83 to 1.27 1.03 0.83 to 1.27
Seldom 3869 171 (4) 1.00 1.00 1.00 1.00
Neighbours (N=8511)
Always/often 102 6 (6) 1.44 0.63 to 3.27 1.12 0.49 to 2.57 0.99 0.43 to 2.27 0.99 0.43 to 2.27
Sometimes 442 26 (6) 1.37 0.89 to 2.11 1.17 0.76 to 1.80 1.09 0.71 to 1.69 1.09 0.71 to 1.69
Never 2330 100 (4) 1.13 0.90 to 1.42 1.11 0.88 to 1.40 1.12 0.89 to 1.41 1.12 0.89 to 1.41
Seldom 5702 281 (5) 1.00 1.00 1.00 1.00
HRs (95% CI) in the Danish Longitudinal Study on Work Unemployment and Health baseline 2000, Denmark.
Model 1 included age and gender, model 2 was further adjusted for baseline occupational social class, cohabitation status, and hospitalisation with chronic diseases from 1980 to
baseline, model 3 added depressive symptoms and model 4 further included perceived emotional support.
Lund R, et al.J Epidemiol Community Health 2014;68:720–727. doi:10.1136/jech-2013-203675 723
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with mortality. There is some support for the vulnerability
hypothesis, as those who were jointly exposed to worries/
demands (HR=3.38: 2.24 to 5.12) or conflicts (HR=4.52: 2.87
to 7.12) and not participating in the labour force were at mark-
edly higher risk of all-cause mortality than those participating in
the labour force with low stress from the partner. Further, the
additive hazards models estimate that the joint exposure to
demands/worries from the partner and being outside the labour
force produces 462 additional cases/100 000 person-years
owing to interaction (95% CI −6 to 930), p=0.05, meaning
that those living on transfer income and who have frequent
demands/worries from their partner have a higher mortality risk
than expected from the individual effects of each of the expo-
sures. Likewise, exposure both to frequent conflicts with the
partner and being outside the labour force produces 830 add-
itional cases/100 000 person-years (95% CI 166 to 1494),
p<0.01.
Worries/demands from the partner also appeared to be modi-
fied by gender as men with many worries/demands from their
partner seemed to have a higher mortality risk than expected
from the individual effects of being a man and being exposed to
worries/demands from the partner (HR=2.50, 95% CI 1.65 to
5.12) with 315 additional cases per 100 000 person-years (95%
CI −28 to 658), p=0.05. The association between conflicts with
partner and mortality was not modified by gender ( figure 2).
There was no support for multiplicative interaction in any of
the analyses.
DISCUSSION
This study suggests that stressful social relations, ranging from
partner to neighbours, are associated with mortality risk among
middle-aged men and women. Conflicts, especially, were asso-
ciated with higher mortality risk regardless of whom was the
source of the conflict. Worries and demands were only asso-
ciated with mortality risk if they were related to partner or chil-
dren. Simultaneous exposure to high levels of stress from the
partner and being outside the labour force appeared to be asso-
ciated with an increased mortality risk, which lends some
support for the theory of differential vulnerability.
14
The
finding is line with empirical studies suggesting an amplified
effect of stressors among the most disadvantaged,
19 20 22
and
Table 3 Conflicts with social relations and all-cause mortality 2000–2011
Model 1 Model 2 Model 3 Model 4
Conflicts Total No No of cases (%) HR 95% CI HR 95% CI HR 95% CI HR 95% CI
Partner (N=7401)
Always/often 451 35 (8) 2.61 1.79 to 3.81 2.19 1.49 to 3.21 1.93 1.30 to 2.87 1.94 1.30 to 2.89
Sometimes 2051 73 (4) 1.25 0.93 to 1.68 1.21 0.90 to 1.62 1.15 0.85 to 1.55 1.15 0.85 to 1.55
Never 1528 75 (5) 1.25 0.94 to 1.68 1.13 0.84 to 1.51 1.16 0.87 to 1.56 1.16 0.87 to 1.56
Seldom 3371 114 (3) 1.00 1.00 1.00 1.00
Trend p value 0.01 0.08 0.09
Children (N=7814)
Always 48 5 (10) 2.38 0.98 to 5.8 2.06 0.84 to 5.05 2.08 0.85 to 5.08 2.07 0.85 to 5.07
Often 395 13 (3) 1.35 0.77 to 2.4 1.27 0.72 to 2.25 1.13 0.63 to 2.01 1.13 0.64 to 2.01
Sometimes 2315 90 (4) 1.24 0.95 to 1.62 1.27 0.97 to 1.65 1.24 0.95 to 1.62 1.25 0.96 to 1.63
Never 1717 103 (6) 1.19 0.92 to 1.53 1.00 0.77 to 1.29 1.01 0.78 to 1.31 1.01 0.78 to 1.31
Seldom 3339 142 (4) 1.00 1.00 1.00 1.00
Trend p value 0.04 0.09 0.09
Other family (N=8666)
Always 52 8 (15) 3.51 1.73 to 7.13 2.64 1.29 to 5.39 2.49 1.22 to 5.09 2.49 1.22 to 5.10
Often 148 16 (11) 3.05 1.83 to 5.08 2.31 1.37 to 3.87 2.07 1.23 to 3.49 2.09 1.24 to 3.54
Sometimes 1400 69 (5) 1.50 1.14 to 1.99 1.36 1.03 to 1.80 1.31 0.99 to 1.73 1.32 0.99 to 1.74
Never 2554 143 (6) 1.20 0.96 to 1.49 1.04 0.83 to 1.30 1.05 0.84 to 1.31 1.05 0.84 to 1.31
Seldom 4512 176 (4) 1.00 1.00 1.00 1.00
Trend p value 0.001 0.005 0.004
Friends (N=8637)
Always/often 41 6 (15) 2.86 1.27 to 6.45 2.63 1.16 to 5.93 2.60 1.15 to 5.88 2.56 1.13 to 5.78
Sometimes 495 37 (8) 1.88 1.32 to 2.67 1.50 1.05 to 2.14 1.44 1.02 to 2.06 1.46 1.02 to 2.09
Never 3836 175 (5) 0.88 0.72 to 1.08 0.87 0.71 to 1.07 0.88 0.72 to 1.09 0.89 0.72 to 1.09
Seldom 4265 199 (5) 1.00 1.00 1.00 1.00
Trend p value 0.001 0.003 0.003
Neighbours (N=8511)
Always 29 8 (28) 5.12 2.50 to 10.49 3.07 1.49 to 6.32 2.89 1.40 to 5.96 2.89 1.40 to 5.97
Often 47 5 (11) 3.45 1.41 to 8.46 2.76 1.12 to 6.80 2.49 1.01 to 6.14 2.47 1.00 to 6.09
Sometimes 396 31 (8) 2.03 1.36 to 3.02 1.78 1.20 to 2.66 1.69 1.13 to 2.52 1.69 1.13 to 2.53
Never 5147 252 (5) 1.17 0.94 to 1.46 1.14 0.91 to 1.42 1.14 0.92 to 1.43 1.15 0.92 to 1.43
Seldom 2892 115 (4) 1.00 1.00 1.00 1.00
Trend p value 0.02 0.04 0.04
HRs (95% CI) in Danish Longitudinal Study on Work Unemployment and Health baseline 2000, Denmark.
Model 1 included age and gender, model 2 was further adjusted for baseline occupational social class, cohabitation status, and hospitalisation with chronic diseases from 1980 to
baseline, model 3 added depressive symptoms and model 4 further included perceived emotional support.
724 Lund R, et al.J Epidemiol Community Health 2014;68:720–727. doi:10.1136/jech-2013-203675
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adds to the literature by focusing on stressful social relations in
private life and all-cause mortality.
In this study, we found that men were especially vulnerable to
frequent worries/demands from their partner, contradicting
earlier findings suggesting that women were more vulnerable to
stressful social relations,
26
but in line with others which suggest
that men respond to stressors with increased levels of cortisol,
which may increase their risk of adverse health outcomes.
31
In
contrast, no gender differences in vulnerability to conflicts with
the partner were identified in this study, as both men and
women seemed to have increased mortality risk with high levels
of conflicts. Further research into the possible gender differ-
ences in vulnerability to stressful social relations is needed in
order to fully understand these mechanisms. Our findings are in
contrast to previous findings which showed no association
between adverse exchange with closest confidant and mortal-
ity.
12
Discrepancy in findings may partly be explained by differ-
ences in categorisation of the exposure variable (dichotomous
12
Figure 1 Joint associations of
stressful social relations with partner
and labour market attachment with
all-cause mortality (N=7401), adjusted
for age, gender, baseline cohabitation
status and hospitalisation 1980–2000,
HRs (95% CI). Many=always/often,
Few=never/seldom/sometimes. Dept,
departure.
Figure 2 Joint associations of
stressful social relations with partner
and gender with mortality (N=7401)
adjusted for age, occupational social
class, baseline cohabitation status and
hospitalisation 1980–2000, HRs (95%
CI). Many=always/often, Few=never/
seldom/sometimes. Dept, departure.
Lund R, et al.J Epidemiol Community Health 2014;68:720–727. doi:10.1136/jech-2013-203675 725
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vs 4–5 levels) as dichotomisation might have blurred differences
across levels. In line with our study, a higher risk of ischaemic
heart disease-related outcomes has been suggested among
people with high levels of demands/worries from partner, chil-
dren and other family members and among those with high
levels of conflict with partner and children.
711
Confounding due to personality factors may be of concern.
Personality has been shown to influence social relationships
41 42
and mortality.
43
Individuals scoring high on agreeableness have
fewer conflicts, whereas those with high levels of neuroticism
have a greater frequency of conflicts.
41 42
High scores on neur-
oticism have been linked to increased mortality in several
studies, whereas the link between agreeableness and mortality is
less clear.
43
If personality plays an important part in the way in
which we perceive our social relations, certain personality traits
may promote the reporting of any social relation as stressful,
and therefore strong correlations between measures of stressful
social relations would be expected. In this study only weak to
moderate correlations were found (Pearson r between 0.14 and
0.54), which reduces the concern of bias. However, part of the
association between stressful social relations and mortality might
be ascribed to personality factors, which were unavailable.
Three main pathways have been suggested as leading from
poor social relations to health outcomes: (1) health behaviour;
(2) psychological well-being and (3) physiological reactions.
Changes in health-related behaviour have been shown to partly
explain the association between social relations and health out-
comes.
44
It has been more difficult to identify potential psycho-
logical pathways.
45
Accordingly, we found that depressive
symptoms did not explain any substantial part of the association
between stressful social relations and mortality. There is rela-
tively strong evidence for the association of social support with
known physiological risk factors for increased mortality such as
atherosclerosis and hypertension.
44
The association between
stressful relations and physiological pathways is less well-
described in population-based studies. Stressful relations have
been associated with heightened proinflammatory cytokine
activity, which points to involvement of the immune system,
9
and to poorer diurnal cortisol regulation,
6
suggesting a possible
pathway via hypothalamus pituitary adrenal axis involvement. It
therefore seems plausible that at least part of the association
between stressful relations and health might be mediated by
stress-responsive systems.
5
Based on prior knowledge and the methods of directed
acyclic graphs, depressive symptoms and emotional support
were identified as potential confounders of the association
between stressful social relations and mortality. However, none
of these factors seem to importantly confound the estimates.
Since very few studies have investigated this association we were
unable to compare these findings with earlier studies.
Strengths of this study include a large sample of middle-aged
men and women with almost complete follow-up, and the use
of validated measures of stressful social relations across a
number of social roles, which allowed us to examine whether
the association differed according to type and social role.
Limitations include the rough dichotomisation of social class
into those in and out of the labour force as well as items for
stressful relations for the interaction analyses, which might have
blurred possible interaction across social class groups and stress
from social relations. Owing to non-response, the study popula-
tion included fewer men, respondents with lower vocational
training and unemployed people than the source population.
Therefore caution should be taken in generalisation of our
results to the general population.
In conclusion, stressful social relations are associated with
increased mortality risk among middle-aged men and women.
Demands and worries from the closest social relations such as
partner and children seem more strongly related to mortality
than worries and demands from more distant relations.
Conflicts across all social roles from partner to neighbours were
associated with higher mortality risk. Furthermore, being simul-
taneously exposed to both stress from the partner and being
outside the labour force was associated with a markedly higher
mortality risk. Likewise men seemed more vulnerable than
women to worries and demands from their partner. Skills in
handling worries and demands from close social relations as
well as conflict management within couples and families and
also in local communities may be important strategies for redu-
cing premature deaths.
What is already known on this subject
▸The health protective effects of high social integration and
access to social support on mortality risk are widely
recognised and have been contrasted with the effects of
well-known risk factors for mortality risk, such as smoking,
alcohol intake and obesity.
▸Less is known about the health consequences of stressful
aspects of social relations, such as conflicts, worries and
demands.
▸Previously, a higher risk of incident cardiovascular outcomes
has been found among those who have frequent conflicts or
worries from social relations, but little is known about the
relationship with all-cause mortality.
What this study adds
▸This study suggests that stressful social relations, ranging
from partner to neighbours, are associated with mortality
risk among middle-aged men and women.
▸Frequent conflicts were associated with higher mortality risk
regardless of the person who was the source of the conflict.
Worries and demands concerning partner and children were
also associated with increased mortality risk.
▸Skills in handling worries and demands from close social
relations as well as conflict management within couples and
families and also in local communities may be considered
important strategies for reducing premature deaths.
Contributors RL conceived the idea for the study, performed statistical analyses
and wrote the first draft. UC contributed to the text and helped in the original data
collection. CJN commented on the text and helped to interpret the results. MK
performed the analyses for additive interaction in R and helped to interpret the
results. NHR commented on the text and helped in interpretation of the analyses.
She particularly contributed to the interpretation and analytical choices for the
interaction analyses.
Funding This work was supported by The Danish Research Council grant number
[9801268] and The Nordea Denmark Foundation grant number [02-2010-0385].
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
726 Lund R, et al.J Epidemiol Community Health 2014;68:720–727. doi:10.1136/jech-2013-203675
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prospective cohort study
Stressful social relations and mortality: a
and Naja Hulvej Rod
Rikke Lund, Ulla Christensen, Charlotte Juul Nilsson, Margit Kriegbaum
doi: 10.1136/jech-2013-203675
online May 8, 2014 2014 68: 720-727 originally publishedJ Epidemiol Community Health
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