Background Rheumatoid Arthritis is associated with subclinical renal impairment which contributes to increase mortality and morbidity. The role of inflammation on kidney function in inflammatory arthritis is not well studied.
Objectives To investigate the associations between estimated glomerular filtration rates (eGFR), traditional cardiovascular risk factors, and markers of inflammation in rheumatoid arthritis compared to healthy controls.
Methods RA patient were recruited through a specialized rheumatology clinic at the Ministry of Health and Prevention of UAE, from January 2013 to January 2016. Healthy subjects recruited from the community through brochure advertisement. The Modification of Diet in Renal Disease Study (MDRD) formula was used to calculate the eGFR. ttest was used to compare the laboratory values and renal function parameters between two groups. Linear regression analysis used to look for the correlation between the eGFR and each of the traditional cardiovascular risk factors and inflammatory markers
Results 98 RA patients and 82 controls were recruited. None of the patients has history of diabetes, atherosclerosis or renal impairment. The mean age for the total participants was 49±13 years (Min16 –Max 82). The mean eGFR of the inflammatory arthritis patients was 118±30 ml/min (range 60–227) and 128±37 ml/min (range 62–286) for the controls. Patients and control had no significant difference in Systolic and diastolic blood pressure.
Inflammatory arthritis patients had lower GFR, albumin (P<0.001), and total protein (p=0.03) levels, and had higher Erythrocyte Sedimentation Rate (ESR) (P<0.001), C-reactive protein (CRP) (P<0.001), and uric acid level (p=0.01),
Negative linear relationships were found as follows:
Among RA patients and controls: There was a negative linear relationship between GFR and each of the age of the participants; (p<0.001, CI: -1.24, -0.40 for the patients and p=0.01, CI: -1.82, -0.26 for the controls), and the systolic blood pressure; (p=0.04, CI: -0.61 for the patients and, -.00 and p=0.022, CI: -0.61, -0.05 for the controls).
Among RA patiens: The GFR had a negative linear relationship with the age of the participants, age at RA onset (p=0.002, CI: -1.18, -0.29), diastolic blood pressure (p=-2.14, CI: -1.24, -0.05), ESR level (p=0.04, CI: -0.24,-0.01), C-reactive protein; CRP level (p=0.02, CI: -0.47, -0.04), uric acid level (p<0.001, CI -0.18, -0.05), and total protein (p=0.01, CI: -0.91, -0.16). There was a positive linear relationship between eGFR and albumin level (p=0.03, p=0.14, 2.35),
Conclusions In RA non-traditional cardiovascular risk factors such as inflammatory markers are associated with sub-clinical presence of renal injury. Our data indicate that in RA, inflammation is involved in the early stages of impaired kidney function. Whether anti-inflammatory therapies are effective in slowing down the deterioration of kidney function in the arthritis diseases remain to be established.
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Nordin, H. and L.M. Pedersen, Kidney function problems in rheumatoid arthritis. Ugeskr Laeger, 1996 158(22): p. 3137–40.
Disclosure of Interest None declared