Clinical presentation and evaluation of the utility of the 4t scoring system in the diagnosis of heparin induced thrombocytopenia among patients at sultan qaboos university hospital

Abstract

Objectives: Heparin induced thrombocytopenia (HIT), albeit uncommon, is a potentially fatal complication heparin therapy. Early diagnosis and prompt intervention has been shown to prevent catastrophic thrombotic complications seen in patients with this condition. The aim of this study is to evaluate the frequency of HIT among Sultan Qaboos University Hospital (SQUH) patients and assess the utility of the 4T scoring system (which is validated clinical tool that predicts the likelihood of HIT). Methods: This is a retrospective cohort study. All patients who were suspected to have HIT and had a HIT assay (by ELISA) between June 2006 and December 2014 were identified from the LabTrack system. Data were collected on their clinical presentation, outcome and the variables included in the 4T scores (i.e. degree of thrombocytopenia, timing of thrombocytopenia, evidence of thrombosis and absence of other causes of thrombocytopenia) were collected using the electronic patient records. The total 4T scores were calculated. Sensitivity, specificity and negative and positive predictive values were calculated. Results: Out of 129 consecutive patients, 64 were males and 65 were females. Mean age was 57years. 9% had thrombosis (% venous, % arterial and % both). 0(and 0%) had a low 4T score (score 0-3), 3(2%) had intermediate (score 4-5) and 6(4.6%) had high scores (score 6-8). 9(7%) of all patients were positive (HIT ELISA optic Density >1.0 unit) and 120(92%) were negative. A positive result was seen in 0 (0%) of the low risk group, 3(2%) of the intermediate risk group and 9(7%) of the high risk group. Conclusion: The study illustrates the validity of the 4Ts scoring system in our patient population with high negative predictive value, in agreement with the published literature. In addition, it illustrates the over use of resources and highlights the need to improve the awareness among clinician about this validated predictive tool to avoid over investigation or over treatment