Blood Pressure In Thrombotic Microangiopathy: Diagnostic Value And Association With The Risk Of Esrd

Objective: Thrombotic microangiopathies (TMAs) constitute a group of diseases with a high renal risk. The epidemiological value of blood pressure (BP) is unknown in TMAs. Design and method: We measured baseline systolic (SBP) and diastolic (DBP) in consecutive 563 patients with adjudicated TMAs, and assessed their association with the risk of end-stage renal disease (ESRD). Results: SBP was <120, 120–139, 140–179 and >=180 mmHg in 26.1%, 19.9%, 43.9% and 10.3% patients, respectively. BP was lower in TMAs related to drugs, malignancies, shiga toxin (STEC) and STEC-unrelated infections, and higher in malignant hypertension, atypical HUS (aHUS) and pregnancy-related TMAs. There was no clear dose-effect association between BP and hematological severity of TMA. Patients with the highest BP values presented more often with acute kidney injury, proteinuria, high uric acid levels, and more often with seizures, headache, visual disturbances and posterior reversible encephalopathy syndrome. When thrombotic thrombocytopenic purpura (TTP) and aHUS were considered together, DBP > 100 mmHg was observed in 0/18 patients with TTP (negative predictive value: 100%) vs 10/15 patients with aHUS (p < 0.0001). Similar findings were observed for SBP > 150 mmHg. BP could not differentiate malignant hypertension from aHUS (some patients had both). Acute dialysis and ESRD occurred in 19.7% and 6.2%, respectively, and varied according to TMA causes. ESRD risk gradually increased with increasing SBP values (odds ratio (OR) vs SBP < 120 mmHg: SBP 120–139 mmHg: 3.53, p = 0.0058; 140–179 mmHg: 18.2, p < 0.0001; >=180 mmHg: 88.8, p < 0.0001, after adjustments on AKI, TMA causes and eculizumab use. Results were similar for DBP. Conclusions: For the first time, the value of BP at the time of TMA was evaluated. BP provides valuable information regarding the identification of the TMA causes. BP value indicates the extent of the TMA-related renal damage. The absence of a clear differentiation between aHUS and malignant hypertension suggests a pathophysiological link between dysregulation of complement alternative pathway and malignant hypertension in some patients.