CKD Severity, Proteinuria Associated With Risk of Prurigo Nodularis

Patients with advanced and end-stage chronic kidney disease (CKD) were associated with an increased risk of developing prurigo nodularis (PN), according to study findings published in Advances in Dermatology and Venereology.

Characterized by intensely itchy nodules on the extensor surface of the limbs and trunk, PN is a rare chronic neurodermatitis condition that affects approximately 72 per 100,000 people in the United States per year. Prior research from epidemiological studies have demonstrated PN to coexist with chronic liver disease, HIV, and type 2 diabetes, among other diseases, but researchers note that the etiological significance of these relationships are not known.

“An increased prevalence of PN has been observed in patients undergoing dialysis. However, little is known of the impact of the degree of kidney dysfunction on PN, including non-dialysis CKD, in the general population,” said the study authors.

They conducted a population-based cohort study of data derived from the Korean National Health Insurance and National Health Screening Program (NHSP) to further examine the influence of CKD on development of PN.

A total of 17,295,576 individuals without prior prurigo nodularis (mean age, 48.3 years; 51.5% male), who took part in the NHSP from January 1, 2009, to December 31, 2010 (baseline health examination), were included in the study. From the date of baseline health examination (index date), participants were followed up until development of new-onset PN (primary outcome), death, or until the end of data collection (August 30, 2019), whichever came first.

CKD severity was determined by the estimated glomerular filtration rate (eGFR; in mL/min/1.73 m²) calculated from serum creatinine, and proteinuria, a marker for kidney damage, was detected with urine dipstick. Other risk factors that may affect PN, such as age, sex, fasting blood glucose, and smoking, were taken into account during the analysis.

From the study cohort, 46.3% had an eGFR greater than or equal to 90, 48.5% between 60 and 89, 4.9% between 30 and 59, 0.1% between 15 and 29, and 0.2% had end-stage renal disease (ESRD; eGFR <15 or receiving dialysis). Over a median (IQR) follow-up period of 9.72 (9.07-10.1) years, 58,599 individuals developed PN, with an incidence rate of 3.59 per 10,000 person-years.

Among different variables, eGFR was the strongest risk factor for PN development. Other risk factors included male sex, age (≥40 years), hyperglycemia (fasting blood sugar ≥126 mg/ dL), smoking, and proteinuria.

The crude PN incidence rate was shown to increase linearly as the eGFR decreased and in the presence of proteinuria. Compared with patients with eGFR greater than or equal to 90, an eGFR of 15 to 29 (HR, 1.31; 95% CI, 1.05-1.62) and ESRD (HR, 1.46; 95% CI, 1.25-1.69) were associated with significantly higher risks.

The presence of proteinuria was also found to independently increase the risk of PN (HR, 1.14; 95% CI, 1.08-1.19), as well as increase risks associated with eGFR 15 to 29 (HR, 2.12; 95% CI, 1.57-2.86) and ESRD (HR, 2.39; 95% CI, 1.81-3.16), and it caused risk associated with eGFR 30 to 59 to become significant (HR, 1.26; 95% CI, 1.07-1.47).

“With the knowledge that CKD increases the risk of PN, preservation of renal function would potentially translate into lower risk of PN,” concluded the study authors. “Control of modifiable risk factors, such as hyperglycaemia, smoking, and proteinuria, may be of great benefit. Reduction in proteinuria can be achieved by using anti-hypertensives, such as angiotensin converting enzyme inhibitors.”

Reference

Kim HS, Kim HJ, Ahn HS. Impact of chronic kidney disease severity on the risk of prurigo nodularis: a population-based cohort study. Acta Derm Venereol. 2022;102:adv00781. doi:10.2340/actadv.v102.2227