Introduction:
Glomerular IgM deposition is commonly seen in primary FSGS and sometimes accompanied by C3 deposition. Clinical presentation and treatment outcomes of these patients are not investigated in detail.
Methods:
120 consecutive patients with biopsy–proven primary FSGS were enrolled retrospectively over 4 years between 2019-2023. They were divided into 3 groups according to their histopathological features: IgM– C3–, IgM+ C3–, and IgM+ C3+. Clinical features and treatment outcomes were compared between patients with and without IgM/C3 deposition Primary outcome was defined as at least a 30% reduction in baseline estimated glomerular filtration rate (eGFR) or development of kidney failure, while complete or partial remission rates were the secondary outcomes.
Results:
Glomerular IgM deposits were found in 70 ( 58.3 %) patients out of total 120 patients, ( 27 patients, 22.5%) of which presented with accompanying C3 deposition ( IgM+, C3+ ) and (43 patients,35.8% ) patients had no depositis of C3 / IgM (IgM–, C3-).
Patients in IgM+ C3+ group had higher level of proteinuria (6.2 ± 1.9 g/24 h, p = 0.001), higher percentage of segmental glomerulosclerosis (24.3± 4.3% , p = 0.01), and lower levels of eGFR (69 ± 37.2 mL/min/1.73 m2, p = 0.02) and low serum albumin (1.41 ± 0.64 g/dL, p = 0.001) at the time of diagnosis.
Decline in egfr > 30% reduction in baseline was seen in more in IgM+ C3+ group compared with IgM– C3– or IgM+ C3– group (33.3% versus 9.3% versus 4%, respectively; p-0.001). Combined IgM and C3 deposition (OR-5.67; 95% CI:1.34 to 23.84; P-0.01) was identified as an independent risk factor for renal dysfunction.
Although patients received comparable immunosuppressive treatments during follow-up, remission rates were lower in patients with combined IgM and C3 deposition compared with patients with IgM deposition alone or no IgM deposition (74% versus 65.1% versus 44.4%, respectively, p-0.03).
Multivariate analysis identified combined IgM and C3 deposition (OR- 11.32; 95% CI: 2.26 to 56.65; P-0.003) as an independent risk factor for refractory patients.
Conclusions:
Patients with primary FSGS and IgM and C3 deposition showed unfavorable therapeutic responses and worse renal outcomes, which indicate that IgM and C3 deposition might involve disease progression via complement activation.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.