SAT-187 EPIDEMIOLOGY 0F CHRONIC TUBULO-INTERSTITIAL NEPHRITIS IN A NEPHROLOGY SERVICE IN SRI LANKA- ARE THESE CKDu ALL?

Abstract

Epidemic chronic kidney disease (CKD) from agricultural communities in many regions of the world has been termed CKD of unknown cause (CKDu) and has been widely recognized as an idiopathic chronic tubulo-interstitial nephritis (iCTIN). This unique CKD which affects people of a similar social stratum and environment, appeared from agricultural communities in these regions around the same period of time, and has very similar clinical and biochemical features. Attempted case definitions of CKDu from Sri Lanka and Central America only narrow it down to a non-proteinuric CKD. CTIN from any cause would fit into these case definitions. In all renal biopsy registries in the world there have been iCTIN, ranging from 11-30%, even before the emergent epidemic of CKDu. In one case series from Texas in 1990, 25% of CTIN were idiopathic and in another series published in 2001, the incidence of iCTIN among Indo-Asians in a London hospital was seven times that of white Caucasians. Obviously, all these cannot be termed CKDu. A retrospective study was conducted in those who underwent renal biopsies at Sri Jayewardenepura General Hospital, Sri Lanka, situated in the non-endemic region for CKDu, but gets many referrals from the endemic area. All case records of patients who underwent renal biopsies during the period March 2016-March 2018 were analyzed. 1218 patients with CKD were treated during this period. 297 underwent a renal biopsy. 77/297 (26%) had primary CTIN. 13/77 (17%) had identifiable causes of CTIN, while the rest-64/77(83%) - were idiopathic. 24/64 (38%) were from known endemic agricultural areas. 14 of 40 from non-endemic areas (35%) were from areas with high agricultural activity. Hence, 26 of the cohort of 64 iCTIN (40%) were from urban or semi-urban areas with neither significant agricultural activity nor occupational exposure to heat stress. Idiopathic CTIN of unknown cause was a recognized biopsy diagnosis even before the CKDu epidemic. The epidemic CKDu which appeared from agricultural communities in Sri Lanka, Central America and India are likely to have similar, if not the same etiology due to the simultaneity of their emergence, and the similar demographic, clinical, biochemical and pathological features. The name CKDu confusingly mixes up all patients with undiagnosed CTIN hence the name CINAC (chronic interstitial nephritis of agricultural communities) is more appropriate to identify the global epidemic CKD identified since the 1990s.