Risk factors for predicting venous thromboembolism in patients with nephrotic syndrome: focus on haemostasis-related parameters.

PURPOSE: The venous thromboembolic events (VTE) incidence is high in nephrotic syndrome (NS). We aimed to assess prospectively the risk of VTE in a large cohort of NS patients and to identify predictive factors for VTE, especially haemostasis-related parameters.

METHODS: This is the prospective, observational study conducted in 256 adults with idiopathic NS. VTE were the study outcome. Clinical data, proteinuria, albuminuria, haemostasis and fibrinolysis parameters, and D-dimers were evaluated every 6 months.

RESULTS: Median follow-up time was 24 [IQR 12–72] months. VTE cumulative and rate incidence were 11 % and 4.4 per 100 patient-years. Baseline higher proteinuria,lower serum albumin, low antithrombin III activity, and,surprisingly, high ionized calcium were VTE independent predictors. Proteinuria and serum albumin cut-offs, and positive and negative predictive values (PPV and NPV) for VTE were 9.0 g/24 h (30 % PPV and 90 % NPV) and 1.5 g/dL (69 % PPV and 93 % NPV).

CONCLUSIONS: The rate of VTE incidence of 4.4 per 100 patient-years found in this prospective study confirms the idiopathic nephrotic syndrome as a thromboembolism-generating condition. Severe and unremitting proteinuria and hypoalbuminemia,low antithrombin III activity, and, surprisingly, high ionized calcium are independent VTE predictors.