Italian iTTP Registry

Age at the first acute iTTP episode in years

ABO/Rh blood group

Body mass index in kg/m^2

Proportion of iTTP patients with comorbidities

Proportion of potential triggering conditions/events/drugs occured/taken in the 3 months prior the acute iTTP episode

Incidence, type and severity of clinical manifestations at presentation of the acute iTTP episode

Platelet count at presentation of the acute iTTP episode, expressed in number x 10^9/L

Hemoglobin level at presentation of the acute iTTP episode, expressed in g/dL

LDH level at presentation of the acute iTTP episode, expressed in IU/L

Creatinine level at presentation of the acute iTTP episode, expressed in mg/dL

Cardiac troponin level at presentation of the acute iTTP episode, expressed in ng/L

Level of functional ADAMTS13 activity expressed in IU/dL or %

Concentration or presence/absence of anti-ADAMTS13 antibodies

Number of daily therapeutic plasma exchange procedures to achieve clinical response of the acute iTTP episode

Incidence, type and severity of TTP-related drugs adverse events recorded during the acute iTTP episode and disease remission of iTTP patients

Proportion of iTTP patients achieving clinical remission defined as sustained clinical response with either no therapeutic plasma exchange (TPE) and no anti-von Willebrand factor (VWF) therapy for ≥ 30 days or with attainment of ADAMTS13 remission, whichever occurs first.

Proportion of iTTP patients refractory to acute iTTP treatment. Refractoriness defined as persistent thrombocytopenia and a persistently raised LDH level despite treatment.

Proportion of patients who experience complications during the hospitalization for acute iTTP

Proportion of iTTP patients experiencing clinical exacerbation defined as sustained platelet count ≥ 150 × 109/L (or above the local lower limit of normal [LLN]) and LDH < 1.5 times hte upper limit of normal (ULN) and no clinical evidence of new or progressive ischemic organ injury.

Proportion of iTTP patients achieving ADAMTS13 remission defined as ADAMTS13 activity ≥ 20% to < LLN (partial) or ADAMTS13 activity ≥ LLN (complete).

Proportion of iTTP patients with a clinical relapse defined as a platelet count decrease to < 150 × 109/L (with other causes of thrombocytopenia ruled out), with or without clinical evidence of new ischemic organ injury, after a clinical remission.

Proportion of iTTP patients with an ADAMTS13 relapse defined as a decrease of ADAMTS13 activity to < 20% after a partial or complete ADAMTS13 remission.

The number of all TTP events (first events and relapses) and first TTP events will be divided by the number of people at risk multiplied by the observation time to estimate the incidence rate of iTTP events and iTTP incident cases, respectively (in persons-years).