Findings appeared this month in the Journal of the American Academy of Dermatology.
A new study based on data from a well-known US health survey finds that adults in this country with psoriasis face a 2-fold mortality risk after adjusting for demographics, smoking, and comorbidities.
Authors of the study, which appeared in the Journal of the American Academy of Dermatology, note this risk of early death is higher than what has been reported in Europe and that much of it cannot be explained. The authors, led by Yevgeniy R. Semenov, MD, MA, of Washington University School of Medicine in St. Louis, suggest reasons they say warrant more study.
Psoriasis, no longer considered just a skin condition despite the telltale rash, is now understood to be a complex inflammatory disorder that involves multiple systems of the body. While cardiovascular disease (CVD), cancer, and COPD are often cited as leading causes of death for people with psoriasis, this new study used mediation analyses to show these reasons “account for only a minority of the overall mortality risk in this population.”
“These findings suggest that a significant portion of the mortality burden of psoriasis remains unexplained and merits further investigation,” the authors write.
The retrospective population-based cohort study examined responses from 13,031 adults and adolescents over 10 years of age who took part in the National Health and Nutrition Examination Survey (NHANES) in either 2003-2006 or 2009-2010. Psoriasis status was self-reported, and mortality data was linked from national databases. The study identified 347 patients with psoriasis and 12,684 controls, for a prevalence of 2.7%.
Overall, the patients with psoriasis were older, had shorter mean follow-up time, and were more likely to be white than the controls. They also had higher comorbidity rates than controls:
The patients with had a higher overall mortality rate during the study period: 4.6% vs 2.2%, P = .003.
While cancer, CVD, and pneumonia were the leading causes of death for those with psoriasis, the overall number of deaths was small—these 3 causes accounted for 12 of 16 deaths. Psoriasis was independently associated with a 1.99-fold increased mortality risk, compared to controls (95% CI, 1.01-3.93; P = .047).
The overall mortality risk was comparable to that of individual comorbidities, the authors found; patients were less likely to die if they were female and wealthier and more likely to die if they were older or smoked. Race and education level did not significantly affect mortality.
By contrast, the authors say, population-based studies in Europe have found the mortality risk for psoriasis is much lower: studies cited listed hazard ratios of 1.08 to 1.15 for mild psoriasis and 1.65 to 1.70 for severe cases.
The authors offered possible reasons for this discrepancy, from population reasons to a potentially controversial one: more widespread use of biologics in the United States compared with the United Kingdom, which the authors say has provided most of the data for European studies. “Biologics utilization has been reported in the range of 1% to 8% in the UK and 8% to 25% in the US,” they write.
The authors compared the reasons for mortality between those with psoriasis and those in the control group, and noted comparatively few deaths from CVD and more from pneumonia and cancer among those with psoriasis. Could the immunosuppressive mechanism of biologics, which clear the skin and contribute to enhanced quality of life, account for these results?
“These findings are consistent with previous studies reporting an increased rate of pneumonia-specific mortality and an increased risk of malignancy,” the authors write. Higher risk of infection and neoplasms could be due to the “systemic immune dysregulation inherent to psoriasis and the immunosuppressive actions of systemic and biologic therapies.”
The entire gap between US and UK mortality rates is not due to greater use of biologics in the United States, the authors say, but some of it could be. “Future research should explore whether pathophysiologic mechanisms in psoriasis are independently tied to mortality,” the authors conclude, “and studies should also examine the impact of systemic therapies.”
Limitations in the study are the small number of psoriasis patients and the limited time to follow-up, which led to a very small number of patient deaths in the psoriasis cohort. The authors note that NHANES data does not include patients in institutions, relies on self-reports, and does not include information on severity, disease duration, or treatment status.
More work is needed to understand the mortality risk for US patients, they said.
“An improved understanding of mortality in psoriasis will optimize the screening, diagnosis, and management of patients,” the authors conclude.
Sernenov YR, Herbosa CM, Rogers AT, et al. Psoriasis and mortality in the US: data from the National Health and Nutrition Examination Survey. J Am Acad Dermatol. 2019; pii: S0190-9622(19)32558-7. doi: 10.1016/j.jaad.2019.08.011.