Akira Kuriyama, MD, MPH, PhD, , FCCM
Director
Kurashiki Central Hospitai
Kameoka Kyoto, Japan
Disclosure information not submitted.
Jeffrey Jackson, MD, MPH
Professor
Medical College of Wisconsin, Wisconsin, United States
Disclosure information not submitted.
Title: The ‘4Ts’ score for predicting heparin-induced thrombocytopenia: A meta-analysis
Learning Objectives: Heparin is an important part of treatments for COVID-19, but has a potentially life-threatening adverse event, heparin-induced thrombocytopenia (HIT). Clinical practice guidelines on HIT recommend performing the ‘4Ts’ score in patients suspected of HIT to screen those who need further assessment and treatment. We conducted a systematic review and meta-analysis to assess the diagnostic accuracy of the 4Ts score for predicting HIT.
Methods: We searched Medline, EMBASE, Scopus, ISI Web of Science, the Cochrane Library for eligible studies from inception to July 2021, without language restrictions. We included studies that examined the diagnostic accuracy of the 4Ts score if HIT was explicitly reported as the reference standard. We defined a positive test as the 4Ts score of ≥4 according to the clinical practice guidelines. We pooled sensitivities and specificities using generalized linear mixed model approach to bivariate random-effects meta-analysis. Our primary outcome was HIT diagnosed on clinical grounds and/or with functional HIT assays.
Results: We included 21 studies involving 4295 participants. The pooled sensitivity and specificity of the 4Ts score for predicting HIT was 0.96 (95% CI, 0.89 to 0.99) and 0.47 (95% CI, 0.38 to 0.56), respectively. The pooled positive and negative likelihood ratios were 1.81 (95% CI 1.53–2.13) and 0.08 (95% CI 0.03–0.25), respectively. The area under the summary receiver operating characteristic (SROC) curve was 0.75 (95% CI 0.72–0.79).
Conclusions: The 4Ts score has excellent sensitivity with poor specificity for predicting HIT. That is, the 4Ts score works better ruling out than ruling in HIT. Given that HIT is difficult to diagnose and associated with complications and poor prognosis, it is reasonable for the 4Ts score to not easily rule out those suspected of HIT for further assessment and treatment. Our study thus supports the idea of calculating the 4Ts score, as stated in current clinical practice guidelines.