Workplace social support has been added to the job strain model
as a third major job characteristic in several studies of CVD
(49, 50, Hall, Johnson and Tsou, 1993), all-cause mortality (8,
25), smoking and sedentary behavior (Johannson, Johnson and Hall,
1991), and ambulatory blood pressure (Landsbergis et al., 1994)
as well as a number of studies of psychological strain outcomes
(e.g., 60, 71).
The main effect of low social support on CVD was examined, with
positive associations (25, 49), as well as the interaction between
social support and job strain (8, 25, 49). Social support was
as an effect modifier in the Swedish study of retired men (25)
(increased job strain-mortality risk ratios for those with low
social support), in the Swedish factory worker study (8) (reduced
high latitude-mortality risk ratios for those with high workplace
social support), and in a Swedish national study (49) (increased
high demand-low latitude-CVD prevalence ratios with greater workplace
social isolation).
One study of CVD risk factors (Johannson, Johnson and Hall, 1991)
found an association between smoking and co-worker support, but
only for women. While Landsbergis et al. (1994) found no association
between social support and ambulatory blood pressure among 262
male employees in New York City, an earlier study found significant
associations between a supportive foreman, supportive coworkers
and lower casual diastolic blood pressure among 288 male factory
workers (79).
The combination of job strain and low social support has been
labeled "iso-strain", or "isolated high strain"
work. This approach was proposed since "iso-strain"
is a univariate measure, "a more parsimonious instrument
for measuring and analyzing workplace conditions" (50, p.
272). Only two studies (50, Landsbergis et al., 1994) directly
examined "iso-strain" as a risk factor. Among 7219 employed
Swedish men followed for nine years, "iso-strain" was
associated with CVD morbidity and mortality (50). Among 262 male
employees in New York City, "iso-strain" was associated
with work and home ambulatory blood pressure and with risk of
hypertension (Landsbergis et al., 1994). Social support and health.
Further study of social support and its effect on stress and health
is indicated not only by the job strain studies cited above, but
also by the extensive literature of the beneficial effects of
both workplace and non-work based social support on cardiovascular
and psychological health (20, 42).
Greater social integration is associated with lower mortality
(House, Landis and Umberson, 1988) in various population based
prospective studies. Positive associations between social support
and CHD were found in Alameda County (Berkman and Breslow, 1983),
eastern Finland (Kaplan et al., 1988), Sweden (Orth-Gomer and
Johnson, 1987; Orth-Gomer, Rosengren and Wilhelmsen, 1993), Denmark
(Netterstrom and Juel, 1988) and Tecumseh county, Michigan (House,
Robbins and Metzner, 1982), but not in Honolulu (Reed et al.,
1983), Evans County, Georgia (Schoenbach et al., 1986) or Framingham
(Haynes, Feinleib and Kannel, 1980). [This paragraph is adapted
from a review by Lynda Powell.]
However, a nonsupportive boss was associated with CHD among female
clerical workers in Framingham (Haynes & Feinleib, 1980).
Emotional support has also been associated with lower mortality
following a myocardial infarction (Frasure-Smith and Prince, 1989;
Berkman, Leo-Summers and Horwitz, 1992).
Dressler (1991) reported that social support moderates the effect
of lifestyle incongruity on blood pressure. In laboratory reactivity
studies, social support has been found to buffer the effect of
stress on diastolic blood pressure responses (Gerin et al., 1995).
Many issues remain to be more fully examined, including: the hypothesized
social support "buffering" effect; the respective contributions
of work-based vs. non-work-based social support, instrumental
vs. emotional support, and quality of support vs. extent of social
network; effect modification by gender, race and/or SES; and the
effect of social support on CVD risk factors such as blood pressure.
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