Diagnostic accuracy of the PLASMIC score in patients with suspected thrombotic thrombocytopenic purpura: A systematic review and meta‐analysis

Abstract

Background The PLASMIC score was developed to identify patients with thrombotic microangiopathy who are most likely to have immune thrombotic thrombocytopenic purpura (TTP) and benefit from therapeutic plasma exchange (TPE). PLASMIC scores of 0‐4, 5, and 6‐7 are said to correspond to low, intermediate, and high probability of TTP, respectively. Study Design and Methods We conducted a systematic review and meta‐analysis on the diagnostic accuracy of the PLASMIC score in adults with suspected TTP. We evaluated the sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of PLASMIC score thresholds of ≥5 and ≥6. Study quality was appraised using the QUADAS‐2 tool. Results We identified 13 eligible studies, which collectively enrolled 970 patients. The median prevalence of TTP among eligible studies was 35%. The sensitivity and specificity of a PLASMIC score ≥5 was 0.99 (95% confidence interval [CI], 0.91‐1.00) and 0.57 (95% CI, 0.41‐0.72), respectively. At a prevalence of 35%, the NPV of a PLASMIC score ≥5 was 0.99 (95% CI, 0.92‐1.00). A PLASMIC score ≥6 was associated with a sensitivity and specificity of 0.85 (95% CI, 0.67‐0.94) and 0.89 (95% CI, 0.81‐0.94), respectively. The NPV of a PLASMIC score ≥6 at a prevalence of 35% was 0.92 (95% CI, 0.82‐0.97). Conclusion A PLASMIC score threshold of ≥5 is associated with high sensitivity and NPV and may be a useful screening tool for identifying patients who are unlikely to have TTP and do not require TPE, though prospective assessment is required. A PLASMIC score <6 appears to have insufficient sensitivity to rule out TTP and the need for TPE.

The standard of care for immune thrombotic thrombocytopenic purpura today

“…Clinical scoring systems for assessing the probability of severe ADAMTS-13 deficiency in patients with suspected TTP PLASMIC score ≥5 has a sensitivity and specificity of 0.99 (0.91-1.0, 95% confidence interval [CI]) and 0.57 (0.41-0.72, 95% CI), respectively. 53 These results suggest that a patient with a PLASMIC and 20%), clinical judgement is required for reaching the final diagnosis, and other diagnoses should be considered as well (Figure 1). 17,57 In addition to plasma ADAMTS-13 activity and inhibitors, assessing ADAMTS-13 conformations via a monoclonal antibody binding assay may also aid the diagnosis and differential diagnosis of iTTP.…”

“…Both scoring systems require ruling out the possibility of disseminated malignancy and the history of hematopoitic progenitor transplantation. Several other studies have independently validated the PLASMIC score 51‐54 . Paydary et al performed a meta analysis of 970 cases from 13 eligible studies published and demonstrated that a PLASMIC score ≥5 has a sensitivity and specificity of 0.99 (0.91–1.0, 95% confidence interval [CI]) and 0.57 (0.41–0.72, 95% CI), respectively 53 .…”

“…Several other studies have independently validated the PLASMIC score 51‐54 . Paydary et al performed a meta analysis of 970 cases from 13 eligible studies published and demonstrated that a PLASMIC score ≥5 has a sensitivity and specificity of 0.99 (0.91–1.0, 95% confidence interval [CI]) and 0.57 (0.41–0.72, 95% CI), respectively 53 . These results suggest that a patient with a PLASMIC score <5 may not have iTTP and does not need urgent TPE and/or caplacizumab; a patient with a PLASMIC score ≥5 does not always have iTTP because of its low specificity.…”

Performance of Diagnostic Scores in Thrombotic Microangiopathy Patients in the Intensive Care Unit: A Monocentric Study

“…This was confirmed in several subsequent studies, included in a recent meta-analysis 22 that defined a score of 5 points or more as the optimal cut-off, associated with the highest sensitivity and negative predictive values. In contrast, in the present study, a score of 4 or more was found to provide the best sensitivity, but the PLASMIC score still performed poorly.…”

An Update on COVID-19 Vaccine Induced Thrombotic Thrombocytopenia Syndrome and Some Management Recommendations

“…Primary TMA is a medical emergency with high mortality and morbidity and, as such, requires astute recognition and prompt treatment. The PLASMIC score is a validated tool using easily testable blood markers to predict the likelihood of TTP [ 80 ]. In the absence of other explainable causes whilst awaiting ADAMTS13 results, a PLASMIC score >5 warrants urgent empirical treatment such as using plasma exchange and corticosteroids.…”