[1] Univ Basel, Internal Med Outpatient Dept, CH-4031 Basel, Switzerland
[2] Purdue Univ, Dept Stat, W Lafayette, IN 47907 USA
[3] Univ Bern, Dept Social & Prevent Med, CH-3012 Bern, Switzerland
[4] McMaster Univ, Dept Clin Epidemiol & Biostat, Ctr Hlth Econ & Policy Anal, Hamilton, ON, Canada