Relationships between social isolation, neighborhood poverty, and cancer mortality in a population-based study of US adults.

BACKGROUND:Social isolation is an important determinant of all-cause mortality, with evidence suggesting an association with cancer-specific mortality as well. In this study, we examined the associations between social isolation and neighborhood poverty (independently and jointly) on cancer mortality in a population-based sample of US adults. METHODS:Using data from the Third National Health and Nutrition Examination Survey (NHANES III; 1988-1994), NHANES III Linked Mortality File (through 2011) and 1990 Census, we estimated the relationship between social isolation and high neighborhood poverty and time-to-cancer death using multivariable-adjusted Cox proportional hazards models. We examined the associations of each factor independently and explored the multiplicative and additive interaction effects on cancer mortality risk and also analyzed these associations by sex. RESULTS:Among 16 044 US adults with 17-23 years of follow-up, there were 1133 cancer deaths. Social isolation (HR 1.25, 95% CI: 1.01-1.54) and high neighborhood poverty (HR 1.31, 95% CI: 1.08-1.60) were associated with increased risk of cancer mortality adjusting for age, sex, and race/ethnicity; in sex-specific estimates this increase in risk was evident among females only (HR 1.39, 95% CI: 1.04-1.86). These associations were attenuated upon further adjustment for socioeconomic status. There was no evidence of joint effects of social isolation and high neighborhood poverty on cancer mortality overall or in the sex-stratified models. CONCLUSIONS:These findings suggest that social isolation and higher neighborhood poverty are independently associated with increased risk of cancer mortality, although there is no evidence to support our a priori hypothesis of a joint effect

Relationships between social isolation, neighborhood poverty, and cancer mortality in a population-based study of US adults - Fig 1

<p>Sex-stratified hazard ratios (HR) of the effects of Social Network Index (A) and Neighborhood Poverty (B) on cancer mortality. In model 1, the HRs are unadjusted, in model 2 they are adjusted for race/ethnicity and age, and in model 3 they are adjusted for race/ethnicity, age, education, and poverty income ratio. The error bars represent the 95% confidence intervals around each HR.</p

Cox proportional regression models of the joint effects of and social network index and neighborhood poverty on cancer mortality (unweighted N = 13 499)

<p>Cox proportional regression models of the joint effects of and social network index and neighborhood poverty on cancer mortality (unweighted N = 13 499)</p

Cox proportional hazards models of the associations between social network index and neighborhood poverty with cancer mortality.

<p>Cox proportional hazards models of the associations between social network index and neighborhood poverty with cancer mortality.</p

Weighted demographics characteristics of the study population presented by neighborhood poverty and social network index, NHANES III, N = 16 044.

<p>Weighted demographics characteristics of the study population presented by neighborhood poverty and social network index, NHANES III, N = 16 044.</p