Urban Health: The Climate Vulnerability Index and Cause Specific Mortality in a Large Cohort Followed from 2001 to 2013

Background/Aim: Recently, the Climate Vulnerability Map was developed as a tool for urban adaptation policies and strategies in Rome, Italy. The index of vulnerability, i.e. the degree to which a system is unable to cope with adverse effects of climate conditions, includes variables as night temperature, river flood and extreme rainfall, green proximity, NDVI, urban structure, soil and land cover, and population density. We aimed at investigating the relationship between the vulnerability index and cause-specific mortality. Methods: We used a large administrative cohort, enrolled at 2001 Census. We applied the vulnerability index at residential coordinates of one million 30+ year olds at inclusion. We followed them until they died or until their migration or the end of 2013. We analysed death from non-accidental causes (ICD9: 001-799), cardiovascular causes (ICD9: 390-459), respiratory conditions (ICD9:460-519), and traumatic causes (ICD9:800-924). We used Cox models to investigate the association between quintiles of vulnerability index and cause specific mortality, adjusting for age, sex, level of education, occupation, marital status, place of birth, and census tract socioeconomic position. Results: During the follow-up there were 165,496 deaths from non-accidental causes; 67,883 from cardiovascular; 10,472 from respiratory conditions, and 6,379 from traumatic causes. With increasing vulnerability index there was an increase in mortality from non-accidental causes (5th vs 1st quintile HR=1.04, 95%CI: 1.02-1.06, p-trend<0.001). The estimates were slightly reduced when adjusting for air pollution exposure. The main index component related to the increase was the thermal component (5th vs 1st quintile HR=1.05, 95%CI: 1.03-1.07). The thermal component was related to higher cardiovascular and respiratory mortality risks (5th vs 1st quintile HR=1.05, 95%CI: 1.02-1.08, and HR=1.08, 95%CI: 1.00-1.14, respectively). There was no evidence of association between the vulnerability index and traumatic causes of death. Conclusions: Urban characteristics are important determinants of human health.