Evaluation of resistive index on the renal artery as early predictor factor of renal affection in patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by synovial hyperplasia and inflammation, progressive joint destruction, and significant disability (1). It can occur at any age, but it predominantly affects women, with a peak onset between the ages of 40 and 60. RA etiology is not yet clear, Recent studies have shown that its mechanism is closely related to genetics, environment, and immune response. Genes such as MHC and HLA-DR4 are involved in the occurrence of RA. (2) Renal complications in RA can range from mild abnormalities in kidney function to more severe conditions, such as glomerulonephritis and renal amyloidosis. Understanding these renal complications is crucial for healthcare providers to ensure comprehensive care for RA patients. (3.4) Vasculitis is an uncommon complication of RA (in approximately 2 to 5% of patients), males with RA are more likely (2 to 4 times more likely) than females with RA to develop RV. Rheumatoid vasculitis most often occur in people with at least 10 years of severe disease. Fortunately, recent reports have noted declines in the prevalence of RV ( 5.6). So The renal arterial resistive index (RI)which is a sonographic index of intrarenal arteries defined as (peak systolic velocity - end-diastolic velocity) / peak systolic velocity. The normal range is 0.50-0.70. Elevated values are associated with poorer prognosis in various renal disorders .

Inclusion Criteria:

• Patients of rheumatoid arthritis è renal affection
• Patients of rheumatoid arthritis without renal affection
• Patients of rheumatoid arthritis on drugs (NSAIDs, DMARDS, methotrexate..).

Exclusion Criteria:

• Diabetic and hypertensive patients, patients with hepatitis B, C viruses or liver cell failure, patients with acute kidney injury, patients with another autoimmune disease as (SLE, sjogren disease, multiple sclerosis, patients with malignancy, patients on another drugs otherwise rheumatoid arthritis drugs).

Base on determining the main outcome variable, the estimated minimum required sample size is 144 cases (48 case in each group)

The sample size was calculated using G*power software 3.1.9.7 based on following assumptions:

Mean serum creatinine level in RA patients without renal affection compared to mean serum creatinine level RA patients with renal affection and control group.

The Effect size is estimated to be 0.3. Main statistical test is one way ANOVA ,Alpha=0.05, power=90