The extent of affected body area in psoriasis may determine mortality

The risk of death for adults with psoriasis that impacts more than 10 percent of body surface area is about 1.8 times greater than adults without psoriasis, according to a new study.¹

Surprisingly, a single measure of psoriasis body surface area involvement, at one point in time, has the power to predict this increased risk of all-cause mortality-an increase that is not evident in psoriasis patients with less than 10 percent body surface area affected.

“The results have important implications for disease management,” according to authors of an accompanying editorial.² “Mortality arguably is the most important measure of the impact of disease on the population health.”

The analysis of 8,760 adults with psoriasis and 87,600 adults without the disease is the first broadly representative study to evaluate how direct measures of psoriasis severity impact death risk, according to the study’s authors.

Researchers conducted a prospective, population-based cohort study using an electronic database of medical records in the United Kingdom. In addition to psoriasis severity, which was measured prospectively through surveys to the patients’ general practitioners, the researchers looked at covariates known to predict mortality, including age, sex, body mass index, alcohol use, socioeconomic status, smoking and medical comorbidities.

They found adults with psoriasis were more likely than those without to have chronic kidney disease, chronic obstructive pulmonary disease, diabetes and a history of heart attack. There were 125 deaths in the psoriasis group, which is a mortality rate of 3.35 deaths for every 1,000 person-years. The death rate per 1000 person-years among adults without psoriasis was 3.24.

The significant differences became clear once the researchers looked at disease severity. Risk of death was 79 percent higher in those with a body surface area of more than 10 percent. And while those with less severe psoriasis might have been at higher risk for important comorbidities, they didn’t have an elevated mortality risk, according to the authors.

In the end, for every 390 severe psoriatic patients, there was an additional death that could not be explained by traditional risk factors for mortality.

This isn’t the first study to suggest psoriasis patients are at increased risk of death, according to the editorial. But the findings of this study are consistent with those of today’s mortality literature, according to the study authors.

A few examples: An analysis by Gelfand et al, published in 2007, found a 40 percent increased mortality risk among patients with severe psoriasis, compared to people without.³ Salahadeen et al’s study published in 2015 showed a reduced lifespan for psoriasis patients, compared to the general population, which worsened with disease severity measured by treatment patterns.⁴

Authors of the editorial suggest psoriasis’s link to increased mortality lies in the long-term effects of systemic inflammation from severe psoriasis. Researchers have documented the mortality impact of severe inflammation associated with rheumatoid arthritis, lupus erythematosus, among other diseases.

Socioeconomic factors, such as income, could also be to blame for higher mortality among people with psoriasis. But more research is needed to determine how socioeconomic variables impact mortality risk in people with psoriasis, authors of the editorial write.

For now, there’s a clear message to dermatologists and others who care for psoriasis patients.

“Based on these results, psoriasis patients identified in the clinical with [body surface area] greater than 10 percent should be targeted for preventative health interventions,” the study authors conclude.

REFERENCES

• Noe MH, Shin DB, Wan MT, Gelfand JM. Objective Measures of Psoriasis Severity Predict Mortality: A Prospective Population-Based Cohort Study. J Invest Dermatol. 2018 Jan;138(1):228-230. doi: 10.1016/j.jid.2017.07.841. http://www.jidonline.org/article/S0022-202X(17)32808-7/fulltext

• Naldi L, Pezzolo E. Back to the Future: Looking at the Skin to Predict Death-A Lesson from Psoriasis. J Invest Dermatol. 2018 Jan;138(1):20-22. doi: 10.1016/j.jid.2017.08.027. http://www.jidonline.org/article/S0022-202X(17)32925-1/fulltext#intraref0010

• Gelfand JM, Troxel AB, Lewis JD, Kurd SK, Shin DB, Wang X, Margolis DJ, Strom BL. The risk of mortality in patients with psoriasis: results from a population-based study. Arch Dermatol. 2007 Dec.https://www.ncbi.nlm.nih.gov/pubmed/18086997

• Salahadeen E, Torp-Pedersen C, Gislason G, Hansen PR, Ahlehoff O. Nationwide population-based study of cause-specific death rates in patients with psoriasis. J Eur Acad Dermatol Venereol. 2015 May. doi: 10.1111/jdv.12523.https://www.ncbi.nlm.nih.gov/pubmed/24909271