Baseline intact fibroblast growth factor 23 and risk of kidney disease progression in the Indian Chronic Kidney Disease cohort: a prospective multicenter study.

Background: Circulating levels of fibroblast growth factor 23 (FGF23) increase early in chronic kidney disease and are associated with a faster progression and increased mortality. However, evidence from South Asia is limited. We investigated the association between baseline intact FGF23 levels and adverse kidney outcomes in the ICKD cohort. Methods: A prospective cohort of adult participants with mild to moderate CKD enrolled at 11 Indian hospitals was included if baseline FGF-23 levels were available. Plasma iFGF-23 was measured using a two-site ELISA. The primary endpoint was major adverse kidney events (MAKE: a composite of kidney failure, ≥50% decline in eGFR, or kidney death). Secondary endpoints included individual MAKE components, all-cause mortality, and cardiovascular mortality. Cox proportional hazards models were used to evaluate the associations between iFGF23 and time-to-event outcomes. Results: A total of 602 participants were followed up for a median duration of 5.3 years. MAKE developed in 266 (49.3%) participants; 223 (41.3%) progressed to kidney failure; 211 (43.5%) reached ≥50% eGFR decline; and 66 (11.0%) died. iFGF23 was significantly associated with MAKE (SHR 1.23, 95% CI 1.02-1.47, Conclusion: In this prospective cohort of Indian CKD patients, iFGF23 levels did not provide independent prognostic information after accounting for established risk factors. Routine iFGF23 testing has limited incremental prognostic value in this setting.