Patients on kidney dialysis who also have psoriasis are at increased risk of infection, and psoriasis treatment can reduce both the risk of infection and death, investigators report.
They looked at data on nearly 9,000 patients with both conditions in the United States Renal Data System, which has information on essentially all patients in the country on dialysis, says Dr. Wendy B. Bollag, cell physiologist in the Medical College of Georgia Department of Physiology and the study’s corresponding author.
What they found indicates psoriasis treatment, which likely helps restore the natural frontline barrier protection of the skin, reduces infection rates and improves survival, indicating its potentially important role in better managing kidney failure, corresponding author Bollag and colleagues at MCG and the Charlie Norwood VA Medical Center in Augusta write.
Prospective studies are needed to further examine these associations, they note in The American Journal of the Medical Sciences.
“We looked at all causes of mortality in this study and also the effect of treatment,” says Dr. Stephanie L. Baer, infectious disease physician in the MCG Department of Medicine and chief of Infection Control and Epidemiology at the Charlie Norwood VA. “The most important thing in this paper is that treatment helped.”
They recommend that physicians taking care of patients who have both conditions be aware of their increased infection risk, and ensure psoriasis treatment as well as vaccination for herpes zoster.
Both psoriasis and kidney failure are known to increase the risk of infection with herpes zoster, the virus that causes shingles and chickenpox, infecting nerves where it can lie dormant for years. The investigators already had shown the virus’ presence is associated with increased death rates in patients in kidney failure. This time they found that this infection actually surfaced more frequently in the face of psoriasis treatment, which supports current recommendations that kidney failure patients get a herpes zoster vaccine, they say.
They suspect the increased risk of infection by herpes zoster and other invaders results from the common, compounding denominator of chronic inflammation caused by both conditions, and the subsequent wear and tear on the vascular and immune systems.
Patients on dialysis are known to be at increased risk of infection because of their typically multiple, weekly visits to a dialysis center and permanent intravenous access lines needed for dialysis, Bollag says, and the loss of barrier protection caused by psoriasis compounds that risk.
They also knew that cardiovascular disease is the leading cause of death in patients on dialysis, that kidney disease is a downstream effect of vascular disease and they suspected psoriasis could further complicate the scenario.
“We know that psoriasis is a proinflammatory syndrome, and we knew that it could increase cardiovascular complications in the general population,” says co-author Baer.
The U.S. Renal Data System is a good system for exploring these kinds of associations, Bollag says, so they decided to find out.
In addition to herpes zoster, they focused on eight other infections common in patients on dialysis, and found psoriasis likely increased their risk of most of them.
They looked for problems like bacteremia, a common bacterial infection in the bloodstream that can result from even a slight injury like vigorous tooth brushing or medical procedures; septicemia, or blood poisoning, the more serious, body-wide illness resulting from significant bacterial infections; conjunctivitis, or pink eye; and cellulitis, a common but potentially significant bacterial skin infection that can occur in inflamed skin.
The most common infections they found were septicemia and cellulitis, which occurred in about half of kidney failure patients with psoriasis, and systemic inflammatory response syndrome, or SIRS, an overwhelming, body-wide inflammatory response to something like a severe bacterial infection or trauma, in 42%.
They also looked at three categories of treatment patients received, which have procedure codes so they could search for them in the huge national database. These include treatments with a body-wide, or systemic, impact like biologics, therapies made from living material like the RNA vaccines in use against COVID-19, or in the case of psoriasis, drugs that specifically block drivers of the immune response called T cells or block proteins immune cells produce like tumor necrosis factor alpha, which promote inflammation. Other treatments included were localized ones like corticosteroid injections directly into a psoriasis lesion, and light-based therapy like ultraviolet therapy that inhibits the immune response in the skin.
The investigators noted that information was not included in the database for all treatments, like self-administered topical creams, and it has been reported that overall a significant percentage of even moderate to severe psoriasis is undertreated or untreated, and that inadequate treatment can worsen the disease.
In this case, they found the therapies that work to suppress the effect of an overzealous immune response were effective at reducing both infection and death.
Now the investigators are pursuing associations between psoriasis and stroke as well as heart attack.
Baer notes that psoriasis may seem like a more chronic, secondary problem in the face of kidney failure, but the reality is both conditions put patients at increased risk for infections and have inflammation and vascular damage as major factors.
The federally funded U.S. Renal Data System collects, analyzes and makes available information on patients who require dialysis because of chronic kidney disease or end stage renal disease. MCG and VA investigators looked specifically at all patients in the database ages 18 and older starting dialysis between 2004-11 — a total of 8,911 individuals — who also had a diagnosis of psoriasis.
About 1% of the patients in kidney failure also had psoriasis and they tended to be older, white, tobacco users and had higher rates of all nine infections the investigators looked at. The investigators noted that it’s highly likely more patients in the database have psoriasis but that diagnosis was not noted.
Other recent population database studies have indicated that having psoriasis increases the risk of kidney disease.
About 7.5 million Americans are living with psoriasis, and 10-20% of patients will also develop psoriatic arthritis, according to the Centers for Disease Control and Prevention.
The typically cyclical, but chronic condition causes patches of thick, red, flaky, sometimes painful skin, most often in places like the elbows, knees and face, but can even surface inside the mouth and on the face, lips and soles of the feet.
Psoriasis is characterized as an immune-mediated disease, in which an overactive immune response dramatically accelerates skin cell growth, according to the National Psoriasis Foundation. While skin cells turn over comparatively rapidly, they go from being produced and shed in about a month to just a few days, which causes the raised pileup that looks distinctive from the rest of the skin.
More than half of patients report the disease to be a major problem in everyday life, the foundation says, and patients are known to be at increased risk for problems like heart attack, stroke and diabetes, in which inflammation also is a major factor.
The research was supported in part by a VA Merit Award (#CX001357).
Read the full study.