Background Research on the social determinants of health is increasingly using welfare regime theory. Although a key argument is that population health will be better and health inequalities lower in social democratic regimes than in others, this research has not been subjected to a systematic review. This paper identifies and assesses empirical studies that explicitly use a welfare regime typology in comparative health research.

Methods 15 electronic databases and relevant bibliographies were searched to identify empirical studies published in English-language journals from January 1970 to February 2011. Thirty-three studies appearing in 14 peer-reviewed journals between 1994 and 2011 met the inclusion criteria.

Results Three welfare regime typologies and their variants dominated existing work, which consisted of two broad study types: One compared population health and health inequalities across welfare regimes; the other considered relationships between health and the political determinants and policies of welfare regimes. Studies were further distinguished by the presence or absence of statistical significance testing of relationships of interest. Just under one half of studies comparing outcomes by regime found at least some evidence that health inequalities were lowest or population health was the best in social democratic countries. Studies analysing the relationship between health (mortality) and the political determinants or policies of welfare states were more likely to report results consistent with welfare regime theory.

Conclusions Health differences by regime were not always consistent with welfare regime theory. Measurement of policy instruments or outcomes of welfare regimes may be more promising for public health research than the use of typologies alone.