Nutritional-inflammatory and laboratory-derived fibrosis indices in FMF-related AA amyloidosis: associations with advanced kidney disease and mortality
Abstract
Aims: Amyloid A (AA) amyloidosis is among the most serious systemic consequences of familial Mediterranean fever (FMF), particularly because of its renal burden. We investigated whether the fibrosis-4 index (FIB-4), the Aspartate Aminotransferase to-Platelet Ratio Index (APRI), HALP, and Prognostic Nutritional Index (PNI), calculated from routinely obtained laboratory data, were related to advanced kidney disease and all-cause mortality in this population. Methods: We retrospectively analyzed adults with FMF and AA amyloidosis at a single center. FIB-4 APRI, HALP, and PNI were derived from each patient’s most recent eligible laboratory assessment. Their relationships with all-cause mortality were examined with Cox regression, while chronic kidney disease (CKD) G5 was analyzed as a cross-sectional binary outcome using logistic regression. PNI and FIB-4 were entered simultaneously in two-variable models; no additional clinical covariates were included. Because the indices were derived from last-available measurements, the analyses were intended to assess association rather than prospective prediction. Results: Fifteen of 97 patients died over a median observation period of 89.8 months, while CKD G5 was present in 28 of the 95 patients with available renal classification. Lower PNI values were observed both among patients who died and among those with CKD G5, whereas higher FIB-4 values characterized the latter group. With both indices included in the models, each 1-point increase in PNI corresponded to a lower mortality hazard (HR, 0.90; 95% CI, 0.84–0.96; p=0.001) and lower odds of CKD G5 (OR, 0.92; 95% CI, 0.86–0.98; p=0.009). FIB-4 showed associations in univariable models, but these became weaker after mutual adjustment. Conclusion: PNI showed the more consistent relationship with mortality and advanced kidney disease, while the findings for FIB-4 were less robust after mutual adjustment. Because both indices are readily obtainable from routine laboratory data, they may offer complementary information on systemic disease burden; prospective studies using predefined baseline measurements are needed before prognostic application.