Risk Factors for Psoriasis: An Umbrella Review of 12 Published Metanalyses

OBJECTIVES: An umbrella review was conducted to identify and compile existing evidence linking biomarkers, lifestyle, and medications, to the risk of developing psoriasis. Evidence stratification was used to facilitate the objective, standardised classification of evidence levels.

METHODS: Electronic databases (EMBASE, MEDLINE, and the COCHRANE library) were searched in May 2024. Meta-analyses of observational studies investigating associations between biomarkers, lifestyle factors, or medications, and the risk of developing psoriasis were included. The summary effect size and 95% confidence interval (CI) were estimated for each meta-analysis. Studies were stratified into five ordinal categories, based on strength of evidence, from convincing (Class I) to non-significant (Class V). Components of the evidence stratification included between–study heterogeneity (I2), the 95% prediction interval, and tests for small-study effects and excess significance bias.

RESULTS: Twelve reviews fulfilled the selection criteria, with 28 unique risk factors for psoriasis including biomarkers (n=15), lifestyle factors (n=9), and medications (n=4) identified. A significant association was reported between 24 (85.7%) risk factors and psoriasis risk (p<0.05), under random-effects models. Convincing (Class I) evidence for an association between the risk of developing psoriasis and former versus never smoking was indicated (odds ratio: 1.62, [95% CI: 1.34, 1.95]). Highly suggestive (Class II) evidence of an association was indicated for: current versus never smoking, increased triglycerides and very low-density lipoprotein (VLDL), and three measures of adiposity (waist circumference, waist to hip ratio and weight). Eight risk factors demonstrated suggestive evidence and nine risk factors weak evidence.

CONCLUSIONS: A highly suggestive association was identified between smoking status, various measures of adiposity, elevated levels of triglycerides and VLDL, and the risk of developing psoriasis. Although substantial heterogeneity and/or bias was evident among the studies in the meta-analyses reviewed, the classification of evidence guides the interpretation of the varying evidence quality established from this umbrella review.