P0474UTILITY OF NATIVE KIDNEY BIOPSY IN OLDER ADULTS: SAFETY AND DIAGNOSES
Authors: Tan Hui Zhuan , Lim Cynthia , Foo Marjorie , Tan Chieh Suai , Choo Jason 
Published: June 2020

Abstract

Background and Aims
Population aging is an increasing phenomenon worldwide and consequently more are developing kidney diseases which may necessitate diagnostic kidney biopsy. However, older patients may be at increased risk for complications such as bleeding. We aimed to examine the utility and safety of native kidney biopsies among our older adults.

Method
This was a single-centre retrospective study of older adults (≥60 years) who had native kidney biopsies at the Singapore General Hospital between June 2011 and March 2015. Demographic data, co-morbid illnesses, clinical presentation at kidney biopsy, as well as laboratory results before and after kidney biopsy, were retrieved from electronic medical records. Patient outcomes were recorded until their last visit or death before 30th March 2017. End stage renal disease (ESRD) was defined as estimated glomerular filtration rate (eGFR) &lt;15 ml/min/1.73 m2 or need for renal replacement therapy persisting &gt;3 months. All post biopsy bleeding events were documented, with major bleeding defined as the need for transfusion and/or intervention; or if bleeding was either a direct or contributory cause of death.

Results
Older adults accounted for 153 of 545 (28.1%) native renal biopsies performed. The indications for biopsy in older adults included microscopic hematuria with proteinuria (51.0%), nephrotic syndrome (32.0%) and isolated proteinuria (17.0%). One hundred and ten patients (71.9%) had eGFR &lt;60ml/min/1.72m2 at biopsy and a significantly higher proportion of older patients (85.5% vs 62.4%, p&lt;0.001) had eGFR &lt;30ml/min/1.72m2. Compared to the younger individuals &lt;60 years old, older patients were more likely to be hypertensive (86.3% vs 58.4%, p&lt;0.001) and diabetic (49.0% vs 28.1%, p&lt;0.001).
Post biopsy, major bleeding was more frequent among older adults compared with younger adults (13.3% vs 5.7% respectively; p=0.04), although overall bleeding episodes between older and younger adults were not significantly different (15.9% vs 22.9% respectively; p=0.18).
Among older adults, minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS) was the most frequent diagnosis (23.5%), followed by membranous nephropathy (20.9%) and IgA nephropathy (9.8%), whereas MCD/FSGS (26.5%), lupus nephritis (24.5%) and IgA nephropathy (19.6%) were the top three diagnoses amongst younger adults. Co-existing glomerulonephritis (GN) with diabetic nephropathy and isolated diabetic nephropathy were seen in 12 (7.8%) and 20 (13.1%) elderly patients respectively. The majority (124 patients, 81.0%) of biopsies in older adults had histological diagnoses of glomerulonephritis that were potentially amendable to treatment although only 90 (58.8%) patients subsequently received immunosuppressants.
Among older adults with biopsy-proven glomerulonephritis, median follow up was similar between those treated and not treated with immunosuppressants (30.4 [27.3, 53.7] months versus 38.8 [30.7, 51.9] months, p=0.12). Among older adults with GN, ESRD was less frequent among those treated with immunosuppressants, compared to those who did not receive immunosuppressants, although the difference did not reach statistical significance (10.3% versus 18.9%, p=0.24). However, the combined endpoint of ESRD or mortality were similar (24.1% vs 21.6%, p=0.76).

Conclusion
Our findings support the utility of renal biopsy for diagnosis and to guide clinical care. Older adults undergoing kidney biopsy should be counselled and monitored for bleeding complications.