No association of neighbourhood volunteerism with mortality in New Zealand: a national multilevel cohort study.
BACKGROUND
The association of social capital with health and mortality is contentious, and empirical findings are inconsistent. This study tests the association of neighbourhood-level volunteerism with mortality.


METHODS
Cohort study of 1996 New Zealand census respondents aged 25-74 years (4.75 million person years) using multilevel Poisson regression analyses. Neighbourhood (average population 2,034) measures included indices of social capital (volunteering activities for all census respondents) and deprivation.


RESULTS
Adjusting for just age and marital status, the mortality rate ratios for people living in the quintile of neighbourhoods with the lowest compared with highest volunteerism were 1.16 (95% confidence interval 1.08-1.24) and 1.09 (1.01-1.18), for males and females, respectively. Adjusting for potential individual-level and neighbourhood-level socioeconomic confounders reduced the rate ratios to 0.94 (0.88-1.01) and 0.92 (0.85-1.01), respectively. There was no significant association with any cause of death, including suicide [rate ratios 0.89 (0.64-1.22) and 0.57 (0.31-1.05), respectively]. Restricting the analyses to only those census respondents living at their census night address for five or more years, and therefore 'exposed' to that level of volunteerism for a longer period, did not substantially alter findings.


CONCLUSIONS
This study, one of the largest multilevel studies yet, found no statistically significant independent association of a structural measure of neighbourhood social capital with mortality-including suicide. Assuming social features of neighbourhoods are important determinants of health, future research should examine other features (e.g. social fragmentation) and other outcomes (e.g. behaviour).
Blakely
Tony
T
Department of Public Health, Wellington School of Medicine and Health Sciences, University of Otago, New Zealand. tony.blakely@otago.ac.nz
Atkinson
June
J
Ivory
Vivienne
V
Collings
Sunny
S
Wilton
Jenny
J
Howden-Chapman
Philippa
P
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality; D009520:New Zealand; D011610:Psychosocial Deprivation; D012944:Social Support; D013405:Suicide; D014838:Volunteers