Association between serum α1-antitrypsin levels and all-cause mortality in the general population: the Nagahama study

Circulating levels of inflammatory proteins have to be prognostic markers of all-cause mortality. α1-Antitrypsin (AAT) is a major inflammatory plasma protein, but its association with all-cause mortality is unclear. We aimed to evaluate the prognostic significance of AAT levels for all-cause mortality. Study participants comprised 9682 community residents (53.5 ± 13.3 years old). During the 9.8-year follow-up period, 313 participants died from any cause. The mortality rate increased linearly with AAT quintiles (Q1, 18.2; Q2, 24.7; Q3, 23.8; Q4, 31.9; Q5, 64.6 per 10,000 person-years). There were significant correlations between AAT and high-sensitivity C-reactive protein (hsCRP) levels (correlation coefficient, 0.331; P < 0.001). However, the Cox model analysis, when adjusted for possible covariates including hsCRP, identified the fifth AAT quintile as a risk factor for all-cause death (hazard ratio, 2.12 [95% confidence interval, 1.41–3.18]; P < 0.001). An analysis of participants older than 50 years (hazard ratio, 1.98, P < 0.001) yielded similar results. The hazard ratio increased proportionately in combination with high AAT and high hsCRP levels, and the highest hazard ratio reached 4.51 (95% confidence interval, 3.14–6.54, P < 0.001). High AAT levels were determined to be an independent risk factor for mortality in the general population.