Risk of moderate to advanced kidney disease in patients with psoriasis: population based cohort study

OBJECTIVE To determine the risk of chronic kidney disease in patients with psoriasis. DESIGN Population based cohort study and nested cross sectional study. SETTING Electronic medical records database based in United Kingdom. PARTICIPANTS Cohort study: patients with psoriasis aged 18-90 each matched to up to five patients without psoriasis based on age, practice, and time of visit. Nested study: patients with psoriasis aged 25-64 with confirmed data on psoriasis severity, each matched to up to 10 patients without psoriasis based on age and practice. MAIN OUTCOME MEASURES Cohort study: incident moderate to advanced (stage 3 through 5) chronic kidney disease. Nested study: baseline prevalence of chronic kidney disease. RESULTS 136,529 patients with mild psoriasis and 7354 patients with severe psoriasis based on treatment patterns were matched to 689,702 unaffected patients. The adjusted hazard ratios (95% confidence intervals) for incident chronic kidney disease were 1.05 (1.02 to 1.07), 0.99 (0.97 to 1.02), and 1.93 (1.79 to 2.08) in the overall, mild, and severe psoriasis groups, respectively. Age was a significant effect modifier in the severe psoriasis group, with age specific adjusted hazard ratios (95% confidence intervals) of 3.82 (3.15 to 4.64) and 2.00 (1.86 to 2.17) for patients aged 30 and 60, respectively. In the nested analysis of 8731 patients with psoriasis with measurements of affected body surface area matched to 87,310 patients without psoriasis, the adjusted odds ratios (95% confidence intervals) for chronic kidney disease were 0.89 (0.72 to 1.10), 1.36 (1.06 to 1.74), and 1.58 (1.07 to 2.34) in the mild, moderate, and severe psoriasis groups, respectively. CONCLUSIONS Moderate to severe psoriasis is associated with an increased risk of chronic kidney disease independent of traditional risk factors.