[1] Univ Clin Essen, West German Lung Ctr, Ruhrlandklin, Dept Pneumol, D-45239 Essen, Germany
[2] Univ Clin Essen, Inst Med Informat Biometry & Epidemiol, D-45239 Essen, Germany
[3] Univ Dusseldorf, Univ Clin Dusseldorf, Inst Med Sociol, Dusseldorf, Germany
[4] Univ Halle Wittenberg, Fac Med, Inst Clin Epidemiol, D-06108 Halle, Germany
[5] Univ Clin Essen, West German Heart Ctr Essen, Clin Cardiol, D-45239 Essen, Germany
[6] Stiftung Krankenhaus Bethanien, Clin Cardiol, Moers, Germany