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External validation of the PLASMIC score: a clinical prediction tool for thrombotic thrombocytopenic purpura diagnosis and treatment

2017; Elsevier BV; Volume: 16; Issue: 1 Linguagem: Inglês

10.1111/jth.13882

1538-7933

Ang Li, Parisa R Khalighi, Qian Wu, David García,

Renal Transplantation Outcomes and Treatments

Essentials•Severe ADAMTS‐13 deficiency is key to thrombotic thrombocytopenic purpura (TTP) diagnosis.•PLASMIC score predicts ADAMTS‐13 deficiency in suspected TTP with high discrimination.•PLASMIC score is more generalizable with fewer missing data than alternative clinical scores.•PLASMIC score identifies a subgroup of patients lacking significant response to plasma exchange.Summary: BackgroundThe PLASMIC score was recently published to distinguish patients with severe ADAMTS‐13 deficiency from those without for early identification of thrombotic thrombocytopenia purpura (TTP).ObjectiveWe performed an independent external validation of the PLASMIC score for clinical prediction of severe ADAMTS‐13 deficiency.Patients/MethodsWe studied an independent cohort of 112 consecutive hospitalized patients with suspected thrombotic microangiopathy and appropriate ADAMTS‐13 testing (including 21 patients with TTP diagnosis).ResultsThe PLASMIC score model predicted severe ADAMTS‐13 deficiency with a c statistic of 0.94 (0.88–0.98). When dichotomized at high (score 6–7) vs. low‐intermediate risk (score 0–5), the model predicted severe ADAMTS‐13 deficiency with positive predictive value of 72%, negative predictive value of 98%, sensitivity of 90% and specificity of 92%. In the low‐intermediate risk group (score 0–5) there was no significant improvement in overall survival associated with plasma exchange.ConclusionsThe PLASMIC score model had excellent applicability, discrimination and calibration for predicting severe ADAMTS‐13 deficiency. The clinical algorithm allowed identification of a subgroup of patients who lacked a significant response to empiric treatment. Essentials•Severe ADAMTS‐13 deficiency is key to thrombotic thrombocytopenic purpura (TTP) diagnosis.•PLASMIC score predicts ADAMTS‐13 deficiency in suspected TTP with high discrimination.•PLASMIC score is more generalizable with fewer missing data than alternative clinical scores.•PLASMIC score identifies a subgroup of patients lacking significant response to plasma exchange. •Severe ADAMTS‐13 deficiency is key to thrombotic thrombocytopenic purpura (TTP) diagnosis.•PLASMIC score predicts ADAMTS‐13 deficiency in suspected TTP with high discrimination.•PLASMIC score is more generalizable with fewer missing data than alternative clinical scores.•PLASMIC score identifies a subgroup of patients lacking significant response to plasma exchange. The PLASMIC score was recently published to distinguish patients with severe ADAMTS‐13 deficiency from those without for early identification of thrombotic thrombocytopenia purpura (TTP). We performed an independent external validation of the PLASMIC score for clinical prediction of severe ADAMTS‐13 deficiency. We studied an independent cohort of 112 consecutive hospitalized patients with suspected thrombotic microangiopathy and appropriate ADAMTS‐13 testing (including 21 patients with TTP diagnosis). The PLASMIC score model predicted severe ADAMTS‐13 deficiency with a c statistic of 0.94 (0.88–0.98). When dichotomized at high (score 6–7) vs. low‐intermediate risk (score 0–5), the model predicted severe ADAMTS‐13 deficiency with positive predictive value of 72%, negative predictive value of 98%, sensitivity of 90% and specificity of 92%. In the low‐intermediate risk group (score 0–5) there was no significant improvement in overall survival associated with plasma exchange. The PLASMIC score model had excellent applicability, discrimination and calibration for predicting severe ADAMTS‐13 deficiency. The clinical algorithm allowed identification of a subgroup of patients who lacked a significant response to empiric treatment.