The role of socioeconomic status in the relationship between detention and self-rated health among prison detainees in Belgium.

Prisoners are known to report worse health than the general population. Research has also shown that the prison population counts disproportionally more people with a lower socioeconomic status (SES), making it difficult to determine whether the worse self-reported health of prisoners is an effect of their detention or of their lower SES. This study assesses the influence of being in prison on self-rated health and if (and how) this relationship is mediated by SES. Data from detainees were collected in 12 Flemish prisons. To compare with the general population, data from the Belgian national health survey 2013 were used. To estimate the direct and indirect effect of being in prison on self-reported health, mediation analysis was carried out by means of natural effect models using nested counterfactuals. Following previous literature we find that prisoners report worse health than the general population and that SES has a significant influence on subjective health. Our results showed that the direct effect (exp(B) = 3.43; [95% CI: 2.924-4.024]) of being in prison on self-reported health is larger than the indirect effect (through SES) (exp(B) = 1,236; [95% CI: 1.195-1.278]), thus contradicting the hypotheses in previous literature that the SES is the main explanation for variation in self-reported health among prisoners. Lastly, the effect of SES on health is more important for the general population compared to detainees, suggesting that for prisoners the effect of being in prison seems to surpass the effect of SES on health.