Researchers in the US working on UK data found that severe psoriasis increased a person’s risk of death by 50 per cent, whereas milder psoriasis posed no increased risk of death. The researchers suggested people with severe psoriasis die about 4 years earlier than people who do not have the inflammatory skin disease.
The cohort study appears in the December 2007 issue of the Archives of Dermatology and is the work of Dr Joel M. Gelfand and colleagues from the University of Pennsylvania School of Medicine, Philadelphia.
Gelfand and colleagues used general practitioner data spanning 1987 to 2002 from the UK’s General Practice Research Database (GPRD), which is representative of the age, sex, and geographic distribution of the UK population.
The database contains records of patients registered with UK general practitioners. The records contain codes for the types of conditions they were diagnosed with, plus details of any treatment history.
Using the diagnostic codes in the patient records, the researchers compiled three groups: patients with mild psoriasis (total number 133,568), patients with severe psoriasis (total number 3,951) and patients with no diagnostic code for psoriasis, and who had presumably visited their doctor for other reasons.
Patients with no diagnostic code for psoriasis were used as a control group. For each practice, the researchers included 5 times as many control patients as patients with psoriasis.
Mild psoriasis was defined as “any patient with a diagnostic code of psoriasis but no history of systemic therapy.”
Severe psoriasis was defined as “any patient with a diagnostic code of psoriasis and a history of systemic therapy consistent with severe psoriasis”.
Using a statistical method called Cox proportional hazards, the researchers worked out the effect on mortality of mild and severe psoriasis compared with the control group.
The results showed that, over the period of study:
- The death rate of patients with severe psoriasis was nearly twice as high as for those without the disease (21.3 as opposed to 12 per 1,000 patients per year).
- There was no overall effect of mild psoriasis on mortality.
- Severe psoriasis appeared to increase risk of death by 50 per cent.
- This risk persisted after adjusting for other known risk factors linked to mortality, such as smoking status, Body Mass Index (BMI), heart problems, AIDS, dementia, cancer, kidney disease, and many others.
- It also persisted when the researchers excluded patients with inflammatory arthropathy (inflamed joints).
- Male patients with severe psoriasis died on average 3.5 years before patients without the disease.
- Female patients with severe psoriasis died on average 4.4 years before patients without the disease.
The researchers concluded that:
“Patients treated for severe psoriasis have an increased risk of death and die at a younger age than patients without psoriasis.”
There was no information on what the causes of death were; the researchers just established there was a link with severe psoriasis.
Scientists believe psoriasis to be an automimmune disease where skin and blood cells grow faster and become inflamed, leading to the red and swollen sores that appear on the skin of people with the condition.
Dr Elizabeth Horn of the International Psoriasis Council told WebMD that:
“One theory is that this chronic inflammation impacts other organs and systems within the body.”
Gelfand and colleagues have conducted earlier studies showing links between severe psoriasis and increased risk of chronic diseases such as heart disease.
This study appears to show there is a significant difference between the mild and severe forms of the disease. While the study has not found what that is, it highlights the importance of keeping a close eye on patients with severe psoriasis, to make sure they are taking care of their health, and perhaps to screen them more closely for other risk factors, such as heart disease.
According to the National Psoriasis Foundation (US), the disease affects up to 3 per cent of people worldwide, or about 125 million people.
The National Institutes of Health (NIH) estimate there are up to 7.5 million Americans living with psoriasis.
“The Risk of Mortality in Patients With Psoriasis: Results From a Population-Based Study.”
Joel M. Gelfand; Andrea B. Troxel; James D. Lewis; Shanu Kohli Kurd; Daniel B. Shin; Xingmei Wang; David J. Margolis; Brian L. Strom.
Arch Dermatol 2007 143: 1493-1499
Vol. 143 No. 12, December 2007
Written by: Catharine Paddock