#5344 EPIDEMIOLOGY OF GLOMERULAR DISEASES IN THE PRE- AND POST-COVID-19 ERA IN CENTRAL QUEENSLAND, AUSTRALIA
Authors: Thet Zaw , Han Thin , Francis Leo , Aung Nyi , Chau Ken , Ng Shu Kay , Myint Mar , Borg Jennifer , Lam Alfred , Khoo Tien , Ranganathan Dwarakanathan 
Published: June 2023

Abstract

Background and Aims
Development of new onset and recurrent glomerular diseases (GD) following Covid-19 infection or vaccination are increasingly reported in the literature with various proposed pathogenic mechanisms. Australia reported its first case of Covid-19 in January 2020. Currently in Australia, there has been 11.3 million cases of Covid-19 infection and 98% of individuals aged ≥ 16 years received at least 1 dose of Covid-19 vaccination. However, there are no studies in Australia that evaluate the risk of GD after Covid-19 infection or vaccination. We compared kidney biopsy results pre- (01/01/2017-31/12/2019) and post- (01/01/2020-31/12/2022) Covid-19 era to assess for potential changes in the epidemiology of kidney biopsy-proven GD.

Method
In this single-centred retrospective study, all renal biopsies performed in Central Queensland (CQ) between 01/01/2017 and 31/12/2022 were reviewed. This pilot study is a subset of Queensland Kidney Biopsy Registry which has captured all renal biopsies of adults residing in CQ with a regional population of 220,912 with a land area of 497,714 km2.

Results
Eighty-seven percent of the CQ population received at least one dose of Covid-19 vaccination and 53,234 cases of Covid-19 infection were confirmed by rapid antigen test (RAT) as of the end of January 2023. The total number of kidney biopsies performed pre- and post-Covid-19 era were 47 vs 58, respectively, and the majority were native kidney biopsies (94% vs 95%) in CQ whereby the number of nephrologists in the respective catchment areas and access availability to kidney biopsies remained similar. The mean age of patients was 55.3 years (standard deviation, SD 16.4) vs 55.6 years (SD 15.6) and the majority were males (70% vs 62%) and Caucasians (77% vs 76%). No case of recurrent GD was diagnosed in pre-Covid-19 era whereas 5 cases of recurrent GD {2 membranous nephropathy, 1 minimal change disease, 1 lupus nephritis class III-IV, and 1 ANCA associated vasculitis (AAV)} in post-Covid-19 era, p = 0.025. The commonest cause of GD in the pre-Covid-19 era was IgA nephropathy (IgAN) whereas diabetic nephropathy and AAV was the most common GD during the post-Covid-19 era. The incidence of IgAN decreased from 12 cases (18.1 cases/million person years) in pre-Covid-19 era to 3 cases (4.5 cases/million person years) in the post-Covid-19 era (incidence rate ratio, IRR of 0.25, 95% CI 0.05-0.93, p = 0.020). The incidence of diabetic nephropathy increased from 1 case (1.5 cases million person years) during the three years pre-Covid-19 era to 13 cases (19.6 cases/million person years) for three years post-Covid-19 era (IRR of 13.1, 95% CI 1.95-552.47, p = 0.001). In the post-Covid-19 era, the mean age of patients with diabetic nephropathy was 51.2 years (SD 11.9) and the majority were indigenous Australian (n = 8, 62%) with poor diabetic control. They had kidney biopsies for nephrotic range proteinuria with or without acute kidney injury and haematuria. The incidence of AAV increased from 3 cases (4.5 cases/million person years) during the three years pre-Covid-19 era to 10 cases (15.1 cases/million person years) for three years post-Covid-19 era (IRR of 3.4, 95% CI 0.86-18.85, p = 0.052). In the post-Covid-19 era, the mean age of patients with AAV was 68.4 years (SD 16.1) with Caucasian (n = 10, 100%). PR3-AAV (n = 5) and MPO-AAV (n = 5) are equally prevalent, and 3 patients (30%) had concomitant pulmonary complications. Three cases of AAV each occurred in the first and second years and 4 cases in the third year during the post-Covid-19 era. There was no increase in the incidence rate for other types of glomerular diseases.

Conclusion
Our findings suggest the frequency of incident and recurrent GD may vary with the emergence of Covid-19 and steps taken to minimise viral complications that include primary preventative measures via vaccination. Larger epidemiological studies are required to better elucidate the risk of Covid-19 infection and vaccination in relation to GD.