Observational Study of 1-Year Mortality Rates Before and After a Major Earthquake Among Chinese Nonagenarians

Abstract

Little is known about mortality among nonagenarians after an earthquake. Using secondary data analyses from the 2005 study called the Project of Longevity and Aging in Dujiangyan(n = 870), 1-year mortality rates were compared among a pre-earthquake group and a post-earthquake group of nonagenarians. All participants were from Dujiangyan, 50 km from the epicenter of the May 12, 2008 earthquake, in China. The pre-earthquake group was a subset of the 870 Project of Longevity and Aging in Dujiangyan participants, ages 93-95 years at the beginning of "Time Frame 1" (July 2005 through June 2006; n = 228). The post-earthquake group was a different subset of the 870 Project of Longevity and Aging in Dujiangyan participants, ages 93-95 years and alive at the beginning of Time Frame 2 (July 2008 through June 2009; n = 235). Time Frame 2 excluded a 7-week period following the earthquake in order to account for deaths due to trauma. Pre-earthquake health assessment data from the 2005 Project of Longevity and Aging in Dujiangyan study were used to calculate unadjusted/adjusted hazard ratios (HRs) for mortality. One-year mortality rates were 8.3% (19/228) and 16.2% (38/235) in the pre-earthquake group and the post-earthquake group, respectively (p =.01). In unadjusted analyses, only "being in the post-earthquake group" was associated with death (HR = 2.04; 95% confidence interval [CI], 1.17-3.53; p = .011). In the multivariable Cox regression model, being in the post-earthquake group continued to be the strongest risk factor associated with mortality (HR = 2.47; 95% CI, 1.39-4.40; p = .002). Other significant risk factors included impaired cognition (HR = 1.97; 95% CI, 1.10-3.53; p = .024), serum albumin (HR = 0.90; 95% CI, 0.82-0.98; p < .015), and serum triglycerides (HR = 1.51; 95% CI, 1.15-1.99; p = .003). The May 12, 2008 earthquake in Wenchuan, China, was associated with a twofold increase in the 1-year mortality among a group of nonagenarians who lived nearby.