What’s the Latest in Hematology, Oncology, and Infectious Disease?
The American College of Physicians presents subspecialty updates highlighting publications from the preceding year in the Annals of Internal Medicine that impact the practice of medicine. These are invaluable resources for all primary care practitioners, and in essence, are a quick hematology/oncology and infectious disease consultation.
Heparin-induced thrombocytopenia
Heparin-induced thrombocytopenia (HIT) is not the easiest diagnosis to make. There is a scoring system called the “4Ts” that may predict the likelihood of HIT.1,2
1.Thrombocytopenia.
2.Timing of the thrombocytopenia.
3.The presence of thrombosis or other sequelae.
4.The presence or absence of other causes for thrombocytopenia.
Each of the 4Ts is further qualified by three values—each contributes 0-2 points to the score for a maximum of 8 points (1-3 is low risk, 4-5 is intermediate risk, and 6-8 is high risk).
Assigning Value
The three values for each of the 4Ts are:
•Thrombocytopenia: 2 points if the platelet count falls >50% and the platelet nadir is greater than or equal to 20,000 mm3; 1 point if the platelet count has a 30% to 50% decline or nadir is 10,000-19,000 mm3; and 0 points if the platelet count falls <30% or has a nadir of <10,000 mm3.
•Timing of the thrombocytopenia: 2 points if the timing is definitely within 5-10 days of heparin therapy or less than 24 hours if there has been heparin exposure in the prior 30 days; 1 point if 5-10 days are not definite, the onset is after 10 days or less than 24 hours after heparin exposure within the prior 30-100 days; and 0 points if the platelet count declines in 4 days or less without recent exposure to heparin.
•Thrombosis: 2 points for new skin necrosis or a systemic reaction to unfractionated heparin, 1 point for progressive-recurrent thromboses, non-necrotizing skin lesions and suspected/unproven thrombosis; and 0 points for no skin reactions.
•Other causes of thrombocytopenia: Other causes equal 2 points (none), 1 point for possible, not proven; and 0 points for a definite alternative cause.
The Authors’ Recommendations
The authors identified 12 publications (n=3,068 patients)2 in which thrombocytopenia was evaluated by both the 4Ts and a reference standard for HIT. The 4Ts score had a higher negative (.998) predictive value than positive (0.64 for high probability and 0.14 for intermediate). The authors recommended:
•A high score should be followed by laboratory confirmation, but a low one should suggest another cause for thrombocytopenia.
•They also recommend continuing heparin when the 4Ts score is 3 or less, but switching to an alternative anticoagulant when scores are 4 or greater.
In the Area of Infectious Disease
For infectious diseases,1,3 I selected a paper that “create(d) a paradigm shift about antibiotic use in non-pregnant women.” In this study, healthy, sexually active, young women between the ages of 18 and 40 who experienced a urinary tract infection within the month prior to enrollment and who were both asymptomatic with significant bacteriuria (105 colonies on 2 collections) were randomized for antibiotics (based on susceptibility) and no antibiotic treatment plans. Follow-up with cultures occurred at 3, 6, and 12 months.
Antibiotic treatment of asymptomatic bacteruria led to significantly more infections at all follow-up intervals. Women with enterococcus faecalis developed resistant E. coli as a result of antibiotics.
As a practitioner, both of these papers impacted my practice. I will not only continue to apply the 4Ts in the differential diagnosis of HIT, but I will also stratify risk—based on positive and negative predictive values—as suggested by the meta-analysis. I will no longer culture asymptomatic women in a search for UTIs. If a positive culture is referred to me, I will not treat asymptomatic women. ■
REFERENCES
1.Eads JR, Meropol NJ, Spivak JL. Update in hematology and oncology: evidence published in 2012. Ann Intern Med. 2013;158(190):755-760.
2.Cuker A, Gimotty PA, Crowther MA, et. al. Predictive value of the 4Ts scoring system for heparin-induced thrombocytopenia: a systematic review and meta-analysis. Blood. 2012;120(20):4160-4167.
3.Cai T, Mazzoli S, Mondaini N, et al. The role of asymptomatic bactiuria in young women with recurrent urinary tract infections: to treat or not to treat? Clin Infect Dis. 2012;55(6):771-777.
Gregory W. Rutecki, MD, is a professor of medicine in the National Consult Service at the Cleveland Clinic. He is also a member of the editorial board of Consultant. Dr Rutecki reports that he has no relevant financial relationships to disclose.