Interaction Effect of Psoriasis and Cancer on the Risk of All-Cause Mortality: A Prospective Cohort Study of NHANES Data

Abstract Background: The relationship between psoriasis, cancer, and mortality has been reported in observational studies. Considering the high heterogeneity in systematic review and meta-analysis and inconsistent results in previous studies, the association between psoriasis, cancer, and mortality warrants more investigation. The primary objective of this study was to explore the joint impact of psoriasis and cancer on mortality in a representative cohort of adults residing in the United States. Methods: We analysed comprehensive data obtained from the National Health and Nutrition Examination Study conducted during the periods of 2003–2006 and 2009–2014. Multivariable logistic regression analyses were performed to assess the relationship between psoriasis and cancer. The vital status of participants was tracked until 31 December 2019. A four-level variable combining information on psoriasis and cancer was created, and survival probability was evaluated using the Kaplan–Meier curve and Cox regression analysis. Hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were calculated to analyse the association between psoriasis/cancer and all-cause mortality. Results: In total, this study included 15,234 participants, among whom 418 had psoriasis and 1213 had cancer. The findings from the logistic regression analyses indicated a heightened risk of cancer among individuals with psoriasis in comparison to those without psoriasis. Moreover, the risk of skin cancer was higher in participants with psoriasis compared to those without psoriasis. Compared with individuals without cancer and psoriasis, the all-cause mortality HRs were 1.25 (95% CI: 0.87–1.78) for individuals with psoriasis only, 1.48 (95% CI: 1.20–1.82) for participants with cancer only, and 2.28 (95% CI: 1.12–4.63) for individuals with both psoriasis and cancer. Conclusion: The results of our study demonstrated a noteworthy and positive correlation between psoriasis, cancer, and all-cause mortality. These findings indicate that individuals who have both psoriasis and cancer face an increased likelihood of mortality.