Background The prevalence of chronic kidney disease (CKD) in general population is about 10% and is higher among individuals with diabetes, hypertension and autoimmune diseases. Adverse outcomes of CKD can be prevented or delayed through early detection and treatment.
Objectives The aim of this study was to determine the prevalence of CKD in patients with rheumatoid arthritis (RA) and factors associated with its occurrence.
Methods We evaluated unselected patients with RA. A detailed medical history, including course and treatment of RA was taken. The physical examination, laboratory analysis and ultrasonography of the abdomen were performed in each subject.
According to Kidney Diseases Outcome Quality Initiative (KDOQI), the diagnosis of CKD was established based on either presence of kidney damage or decreased glomerular filtration rate (GFR) < 60 ml/min/1.73m2 for at least 3 months. Kidney damage was defined as structural or functional abnormalities of the kidney with or without decreased GFR, manifest by pathologic abnormalities or markers of kidney damage, including abnormalities in composition of the blood or urine or in imaging studies. Stages of CKD was assigned based on the level of kidney function (estimated GFR), according to the KDOQI CKD classification.
The level of GFR was estimated by Modification of Diet in Renal Disease Study equation (MDRD).
Results 111 patients (94 women and 17 men) with RA were included in the study. The mean age was 60.7 years. The mean RA duration was 9.7 years. The mean serum creatinine concentration was 0.7 mg/dl. The mean GFR was 93 ml/min/1.73m2.
Based on the definition above, CKD was diagnosed in 35 patients (31.5 %), of whom 27 had kidney damage with or without decreased GFR and 8 had decreased GFR<60 ml/min/1.73m2 without kidney damage. Among patients with kidney damage, 5 had abnormal blood tests, 3 had abnormal urine tests and 26 had abnormalities in imaging studies.
Among CKD patients, 12 (34.3%) had first, 10 (28.6%) had second and 13 (37.1%) had third stage of the disease.
Significantly higher prevalence of CKD was observed in RA patients with presence of extra-articular manifestations (60% vs 32.9%, p- 0.007) and co-existing hypertension (74.3% vs 49.3%, p- 0.01). There was also significant difference in mean RA duration (13.4 vs 8.2 years, p-0.005) between patients with and without CKD.
No statistically significant difference was found between these two groups for demographic factors (age, gender), smoking status, RA activity indices (morning stiffness, tender and swollen joint count, DAS28, VAS- pain, VAS- activity, HAQ, Steinbrocker radiological stage and functional class), laboratory tests results (ESR, CRP, Hgb) and serological markers (RF, ACPA, ANA, ENA).
Conclusions The prevalence of CKD in patients with RA is 31.5%. RA patients with long-lasting disease, extra-articular manifestations and co-existing hypertension are at increased risk for CKD.
Disclosure of Interest None Declared