In this study, psoriasis with concomitant psoriatic arthritis (PsA) was found to be linked with greater risk of laparoscopically-confirmed endometriosis. Additionally, results indicate a suggestive relationship between endometriosis diagnosis and subsequent risk of psoriasis with PsA.

• In the Nurses’ Health Study II cohort (n=116,429 aged 25-42 years in 1989), the bi-directional links between laparoscopically-confirmed endometriosis, and physician-diagnosed psoriasis and PsA were examined.

• A 2-fold higher risk of endometriosis (HR=2.01) was observed in relation to a history of psoriasis with concomitant PsA, however there was no link between psoriasis without PsA and endometriosis risk (HR=0.93).

• Endometriosis as an exposure was not linked with a risk of subsequent psoriasis (HR=1.28).

• A remarkably higher risk of psoriasis with PsA was observed, however the sample size was small with wide confidence intervals (HR=1.77).