Exploring the causal relationship between psoriasis and osteoarthritis through a 2-sample Mendelian randomization study

Previous research has demonstrated a robust association between osteoarthritis (OA) and psoriasis. Notably, a significant proportion of psoriasis patients exhibit symptoms of arthritis, particularly psoriatic arthritis. However, a definitive causal relationship between psoriasis, psoriatic arthritis and OA remains to be established. This study aimed to elucidate the causal relationship between psoriasis, psoriatic arthritis, and osteoarthritis using a 2-sample Mendelian randomization approach. The causal relationship between psoriasis, psoriatic arthritis and OA was rigorously investigated using a 2-sample Mendelian Randomization (MR) approach. Instrumental variables pertinent to psoriasis, psoriatic arthritis and 4 distinct types of OA (knee osteoarthritis (KOA), hand osteoarthritis (HOA), total knee replacement (TKR), and total hip replacement (THR)) were sourced from extensive, published genome-wide association studies (GWAS). To estimate the causal effects, methodologies such as inverse variance weighting (IVW), MR-Egger, and weighted median estimation (WM) were employed. Mendelian Randomization analysis suggested a potential causal effect of psoriasis on osteoarthritis (OA). For hand OA (HOA), the P value was .381 (OR = 0.28); for knee OA (KOA), the P value was .725 (OR = 1.46); for TKR, the P value was .488 (OR = 0.274); and for THR, the P value was .454 (OR = 0.216). Furthermore, we explored the causality of psoriatic arthritis on OA. For HOA, the P value was .478 (OR = 0.0095); for KOA, the P value was .835 (OR = 0.345); for THR, the P value was .807 (OR = 0.120); and for TKR, the P value was .860 (OR = 0.190). Our findings indicate that there is no evidence of a causal connection between psoriasis or psoriatic arthritis and OA, suggesting that while psoriasis may contribute to arthritis, it does not influence OA development.