Predictors of renal outcomes and mortality in patients with renal vein thrombosis: a retrospective multicenter study.

Background: Studies on renal vein thrombosis have been conducted as case reports or case series. The renal outcomes and mortality risk of renal vein thrombosis have not been fully established. We aimed to investigate the clinical characteristics, treatment modalities, and predictors of renal outcomes and mortality in patients with renal vein thrombosis in a large multicenter cohort.

Methods: We retrospectively assessed 182 patients with renal vein thrombosis diagnosed between January 2011 and May 2023 using either Doppler ultrasonography or computed tomography venography. The main outcomes analyzed were all-cause mortality, and worsening kidney function.

Results: We evaluated 182 patients comprising 76 males (41.8%) and 106 females (58.2%). Nephrotic syndrome was the most common cause (51.6%) followed by malignancy (33%) and post-trauma or surgery (11%). Kidney function worsened in 126 patients (69.2%). Acute kidney injury (AKI) was identified in 72 patients (39.6%), whereas 54 patients (29.7%) developed chronic kidney disease (CKD). Multivariate logistic regression showed that declining kidney function was reliably predicted by nephrotic syndrome (Odds ratio (OR): 6.41, P = 0.004), serum albumin (OR: 0.31, P = 0.003), and diabetes mellitus (OR: 14.04, P < 0.001). Eighty-two patients (45.1%) died while being monitored. Sepsis accounted for the majority of deaths (25.3%). Bilateral renal vein thrombosis (Hazard Ratio (HR): 5.61, P < 0.001), malignancy (HR: 6.15, P = 0.004), serum albumin (HR: 0.12, P < 0.001), hemoglobin (Hb) level (HR: 0.102, P < 0.001) and diabetes mellitus (HR: 2.42, P = 0.007) were all reliable predictors of all-cause mortality using multivariate Cox regression.

Conclusion: Renal vein thrombosis is associated with a higher risk of mortality and worsening kidney function. It is essential to promptly identify high risk patients and start early treatment to prevent unfavorable outcomes.