MORTALITY Body mass index and mortality: results of a cohort of 184,697 adults in Austria Jochen Klenk Æ Gabriele Nagel Æ Hanno Ulmer Æ Alexander Strasak Æ Hans Concin Æ Gu ¨ nter Diem Æ Kilian Rapp Æ The VHM&PP Study Group Received: 8 September 2008 / Accepted: 31 December 2008 / Published online: 29 January 2009 Ó Springer Science+Business Media B.V. 2009 Abstract There is still a debate about the role of body mass index (BMI) as a risk factor for all-cause mortality. Most investigations with large sample sizes focused on populations from the United States, studies from Central- European cohorts are not available. We investigated the association between BMI and all-cause mortality and cause-specific mortality within a cohort in Austria. Design of this article is ‘‘Cohort study’’. The Subjects used were 184,697 men and women (mean age 41.7 ± 15.4 years). Weight and height were measured. Cox proportional haz- ards models were used to estimate hazard ratios (HR). During a median follow-up of 15.1 years 15,557 deaths (6,077 from cardiovascular disease, 4,443 from cancer and 606 from respiratory disease) were seen. A U-shaped association between BMI and all-cause mortality was observed in men and women. Compared with the reference category (BMI 22.5–24.9 kg/m 2 ) high risks were found both in the highest category of BMI (C35 kg/m 2 ) with HR of 2.13 (95% CI, 1.82–2.48) in men and 1.60 (95% CI, 1.42–1.81) in women and in the lowest category ( \ 18.5 kg/ m 2 ) with HR of 2.57 (95% CI, 2.17–3.05) in men and 1.40 (95% CI, 1.21–1.62) in women. Similar patterns were seen among ever-smokers and non-smokers. Increased mortality with increasing BMI was driven by cardiovascular diseases and to a lesser extent by cancers. Respiratory diseases contributed to mortality in the lowest BMI category inde- pendently from smoking status. Underweight and obesity were both associated with higher all-cause mortality in men and women. Keywords Body mass index Á Mortality Á Epidemiology Introduction During the last decades obesity has increased in most in- dustrialised countries and reached alarming dimensions [1]. Studies from different countries with different lifestyles have shown consistently that obesity is associated with an increased risk of all-cause mortality. A near linear rela- tionship between body mass index (BMI) and mortality was usually observed in men and women with a BMI of 30 kg/m 2 and more [2–12]. Some of the large cohort studies like the Nurses Health Study [3], the Cancer Pre- vention Study II [4] or the Korean Cancer Prevention Study [11] were able to perform analyses stratified by the cause of death. They demonstrated that the increased all-cause mortality was mainly due to cardiovascular and cancer mortality. This was not unexpected since obesity is clearly associated with most of the classical cardiovascular risk factors like hypertension, hyperlipiemia and diabetes [13, Electronic supplementary material The online version of this article (doi:10.1007/s10654-009-9312-4) contains supplementary material, which is available to authorized users. J. Klenk (&) Á G. Nagel Á K. Rapp Institute of Epidemiology, University of Ulm, Helmholtzstrasse 22, 89081 Ulm, Germany e-mail: jochen.klenk@uni-ulm.de H. Ulmer Á H. Concin Á G. Diem Agency for Preventive and Social Medicine, Rheinstrasse 61, 6900 Bregenz, Austria H. Ulmer Á A. Strasak Department of Medical Statistics, Informatics and Health Economics, Medical University of Innsbruck, Schoepfstrasse 41, 6020 Innsbruck, Austria K. Rapp Department of Clinical Gerontology, Robert-Bosch-Hospital, Auerbachstrasse 110, 70376 Stuttgart, Germany 123 Eur J Epidemiol (2009) 24:83–91 DOI 10.1007/s10654-009-9312-4