Baseline characteristics of the 3691 primary care patients included in the longitudinal analysis.

Values are means (standard deviation) unless otherwise stated.aVariables derived from the cycle ergometer test at baseline: n = 3089.bSample size for Physical and Mental Component Summary: n = 3652.cSocial class classification based on occupation and work position (30): Class IV to V includes non-qualified and qualified manual workers; Class III includes the administrative workforce, supervisors and freelance workers; Class II includes managers of enterprises with less than ten employees, professionals with first level university degree, senior technicians, artists and sportsmen/women; Class I includes managers of public organizations or private enterprises with more than ten employees, professionals with second and third level university degrees.