Published: Oct 16, 2013 | Updated: Oct 16, 2013
By Chris Kaiser

Full Story:  http://www.medpagetoday.com/Dermatology/Psoriasis/42321

For the first time, researchers say they’ve found an association between moderate and severe psoriasis and chronic kidney disease (CKD).

In a matched cohort where treatment records were used as a proxy for disease severity, the likelihood of someone with severe psoriasis having incident CKD was nearly twice as high as someone with mild psoriasis (adjusted OR 1.93 versus 0.99), according to Joel M. Gelfand, MD, an associate professor of dermatology and epidemiology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, and colleagues.

The risk of CKD was independent of sex, age, cardiovascular disease, diabetes, hypertension, hyperlipidemia, use of nonsteroidal anti-inflammatory drugs, BMI, and duration of observation, they wrote in the study published online in BMJ.

These results were confirmed in a separate nested-analysis in which disease severity (body surface area affected) was assessed via questionnaires sent to general practitioners. The adjusted risk of CKD for psoriasis was:

• Mild psoriasis — OR 0.89 (95% CI 0.72-1.10)
• Moderate — OR 1.36 (95% CI 1.06-1.74)
• Severe — OR 1.58 (95% CI 1.07-2.34)

Those with psoriasis on more than 3% of their body were at greatest risk.

“Although this finding would be not unexpected, the report is the first one to showcase nicely such a significant association with major clinical and public health implications, given high prevalence of psoriasis across all populations,” said Kamyar Kalantar-Zadeh, MD, PhD, an associate professor in the division of nephrology and hypertension at the University of California Irvine, School of Medicine.

It may be too soon to change clinical practice based on this study, Kalantar-Zadeh said, but it should increase awareness about CKD screening in psoriasis.

In August, Gelfand and colleagues found psoriasis was associated with an increased risk for nine diseases, including chronic pulmonary disease, diabetes, mild liver disease, peripheral vascular disease, and rheumatologic disease.

“In the past, dermatologists did not recognize this association, but it has now become a major topic,” Wayne Gulliver, MD, of Memorial University of Newfoundland in St. John’s, toldMedPage Today in August.

Emerging data has found associations between gut bacteria and the immune system, obesity, and atherosclerosis. In 1999, a paper in Integrative Medicine suggested a connection between gut health and psoriasis.

Kalantar-Zadeh said newer data also have shown that patients with psoriasis and patients with CKD have aberrations in gut microbiota. The theory is that the alteration in microbiota compromises the intestinal lining, thereby, allowing more toxic material to be absorbed.

It’s important to emphasize, Kalantar-Zadeh said, that the gut bacteria may be just one aspect of the etiology in these patients.

For the current study, Gelfand and colleagues mined patient data from The Health Improvement Network (THIN), an electronic medical records database maintained by general practitioners in the U.K.

The matched cohort part of the study based on treatment included 136,529 patients (ages 18-90) with mild psoriasis and 7,354 patients with severe psoriasis matched to 689,702 unaffected patients.

The data for the nested analysis came from a substudy called the Incident Health Outcomes and Psoriasis Events (iHOPE) study and included 8,731 severe psoriasis patients and 87,310 controls (ages 25-64).

Despite the association of psoriasis with CKD being independent of the adjusted confounders in the treatment cohort, researchers noted that the relative risk appeared to be highest among younger patients with severe psoriasis.

Patients with severe disease at 20 years old, for example, were five times more likely to have CKD than those with mild disease at the same age. As age increased the risk for CKD decreased. At 30, the risk was less than four times greater; at 40, it was closer to three times greater, and so on.

The team found that the association between severe psoriasis and renal insufficiency was not driven by joint disease or its associated use of nephrotoxic drugs.

The limitations of the study, according to the authors, include potential misclassification bias regarding treatments and ascertainment bias.