Abstract
Background and Aims
Renal involvement is one of the most common extra-articular complications caused by ankylosing spondylitis (AS). The main pathological manifestation is secondary IgA nephropathy(SIgAN) in Chinese AS patients. The difference between SIgAN and primary IgAN (PIgAN) remains unclear due to the lack of cases. Therefore, the aim of this retrospective study was to compare the clinical and pathological features of SIgAN of AS (SIgAN-AS) and PIgAN, to detect the pathogenesis of SIgAN
Method
Clinical characteristics and pathological data were collected in patients who were diagnosed with IgAN by renal biopsy in our hospital from Jan 2008 to Oct 2018. Patients with SIgAN-AS were recruited by the ratio 1:5 of patients with primary IgAN as the control group in the study. Fifteen patients with SIgAN-AS and Seventy-five patients with PIgAN were enrolled in this retrospective study.
Results
There were 15 cases in AS group, including 13 male and 2 female. The cohort of 75 patients with PIgAN included 34 male and 41 female. There were more males in AS group 13/15 (86.7%) vs 37/75(49.3%) ,P < 0.05. Compared with PIgAN patients, SIgAN-AS patients had higher incidences of hematuria( 13/15(86.7%)vs 44/75 (58.7%) , P < 0.05), lower levels of 24-hour urinary protein(0.85±0.68 vs 1.57±1.54g, P < 0.05), but higher levels of eGFR (CKD-MDRD formula) (117.60±37.33 vs 85.35±31.36, P < 0.05),eGFR (CKD-EPI formula) (128.01±41.58 vs 92.75±36.09, P < 0.05), Albumin (44.67±3.48 vs 41.09±7.07 g/L, P < 0.05) ESR (43.20 ±33.94 vs 18.79±16.26mm/h, P < 0.001) , and CRP (21.19±30.61 vs 2.11±4.58mg/L, P < 0.001) . From the perspective of renal pathology of PIgAN, SIgA-AS patients had fewer incidences of renal tubular atrophy / interstitial fibrosis of nephropathy (P <0.05). The immunohistostaining analysis showed higher incidences of dominant deposits of single IgA in mesangial cell area (P < 0.05).
Conclusion
Patients with SIgAN-AS is more common in male and display a milder progression than those with primary IgAN. Majority of the SIgAN-AS can be improved with early intervention.
IgA nephropathy associated with ankylosing spondylitis: occurrence in women as well as in men.