Thus, having a chronic diseases diagnosed a few years ago, if well controlled and treated, may not definitely imply negative labour market outcomes. A further possible explanation is that people with chronic diseases are more likely to be union members, that could prevent from involuntary labour-force exit and reduced wages (Pelkowski et al. Other possible reasons for diverging findings may come from limitations of the data and methods used in the study (e.g. design of the study, estimation error). First, comparability of results is limited due to the use of different national surveys with differences in survey methodology, sampling, and questionnaires.