Table 3.

Interventions to reduce heparin-induced thrombocytopenia overdiagnosis.

Intervention type	Author	Year	Country	Intervention details	Preintervention time frame	Postintervention time frame	Findings
4Ts score calculator
	Samuelson et al. [31]	2015	USA	Mandatory 4Ts score calculator implemented into HIT ELISA EMR order.	8 mo	8 mo	•Reduction in aggregate testing (43 tests/mo vs 22 tests/mo, P < .001). •Reduction in proportion of tested patients with low probability 4Ts scores (66% vs 56%, P = .07). •Increase in average 4Ts score of tested patients (3.0 vs 3.4, P = .01).
	Schaffner et al. [24]a	2017	USA	•Mandatory 4Ts score calculator implemented into HIT ELISA EMR order.	8 mo	8 mo	•161 HIT ELISA orders preintervention (81% negative) vs 105 postintervention (82% negative). •Reduction in HIT ELISA ordering in patients with low probability 4Ts scores (67% vs 57%, P = .13). •4Ts score discordant between ordering provider and hematologist in 67% of cases.
	Tsui et al. [25]a	2017	USA	•Mandatory 4Ts score calculator implemented into HIT ELISA EMR order.	24 mo	24 mo	•213 HIT ELISA orders before intervention vs 189 after intervention. •Fewer tests sent on patients with low probability 4Ts scores (54% vs 30%, P < .001). •More frequent discontinuation of heparin in patients with intermediate probability (66% vs 74%, P < .001). •Higher rates of HIT diagnosis (5.6% vs 11.1%, P < .05).
	Arshad et al. [29]	2018	USA	•Educational sessions for providers •Optional 4Ts score calculator incorporated HIT ELISA EMR order	18 mo	7 mo	•Reduction in inappropriate HIT ELISA orders (86.2% vs 56.4%, P < .001). •Increased documentation of 4Ts score (3.3% vs 30.8%, P < .001). •Increase in proportion of positive ELISA results (4.9% vs 10.3%, P = .22).
	Swarup et al. [27]a/Ball et al. [26]a,b	2018/2019	USA	Mandatory 4Ts score calculator implemented into HIT ELISA EMR order	12 mo	6 mo	•170 HIT ELISA orders preintervention vs 69 postintervention. •Increased 4Ts score documentation (3% vs 100%). •Reduced proportion of patients with low probability 4Ts scores receiving testing (66.4% vs 47.8%). •Increase in number of patients with intermediate or high probability 4Ts scores receiving alternative anticoagulant during testing period (71% vs 88%).
	Baumann Kreuziger et al. [23]a	2019	USA	Mandatory 4Ts score calculator implemented into HIT ELISA EMR order.	6 mo	6 mo	•104 HIT ELISA orders preintervention vs 112 orders postintervention. •Increase in the number of appropriately ordered tests (54% vs 80%, P < .001).
	Zayac et al. [28]	2020	USA	Mandatory 4Ts score calculator implemented into HIT ELISA EMR order.	7 mo	7 mo	•No difference in rates of inappropriate HIT ELISA orders (68.8% vs 66.3%). •No significant difference in rates of 4Ts score documentation
	Obadina et al. [30]	2022	USA	Mandatory 4Ts score calculator implemented into HIT ELISA EMR order; if score ≤3, a clinical reason for testing must be manually entered.	12 mo	12 mo	•4.1% decrease in number of HIT ELISAs performed. •Similar rates of positive HIT ELISAs in preintervention and postintervention (13.6% vs 14.7%). •Fewer tests sent in patients with low probability 4Ts scores (74.5% vs 10.6%).
4Ts score calculated by nonclinicians
	Burnett et al. [32]	2016	USA	Reference laboratory contacts AMS when a HIT ELISA is received; AMS calculates 4Ts score and contacts ordering provider to recommend for or against processing and reporting of laboratory results.	12 mo	12 mo	•Reduction in HIT ELISA orders (176 vs 107, P < .001) •41% reduction in total HIT ELISAs processed by laboratories (176 vs 63, P < .001) •Reduction in inappropriate HIT ELISAs processed (72.2% vs 52.4%, P = 0.004). •Reduction in major bleeding events (10.2% vs 6.5%, P = .279). •Cost savings of 62% per patient exposed to heparin ($19.58 vs $7.51)
	Condon et al. [33]	2020	USA	•HIT ELISA orders trigger page to clinical pharmacist to calculate 4Ts score and determine assay appropriateness. •Order set guiding providers to calculate a 4Ts score with HIT ELISA order along with recommendations based on the score.	12 mo	12 mo	•279 HIT ELISA/SRA orders preintervention (23/mo) vs 177 postintervention (15/mo) •303 pages received by pharmacists, 109 missed due to unavailability of pharmacist at time of page; 194 pages reviewed, 134 intervened on. •107 scored as low risk by 4Ts score, 70 as intermediate risk, 9 as high risk. •64 HIT ELISAs and 11 SRA discontinued due to pharmacist intervention.
Provider education
	Malalur et al. [22]	2019	USA	Implementation of an HIT education program involving lectures to providers and individual feedback from hematology consultants to ordering clinicians.	Not stated	3 mo	•83.3% of HIT ELISA orders were sent on low-risk cases, 12.5% on intermediate-risk, and 4.2% on high-risk cases.
Laboratory stewardship of SRA testing
	Cusick et al. [34]	2022	USA	SRA test completion controlled by laboratory; SRA only sent for analysis if HIT ELISA returned with OD ≥ 0.400 units	23 mo	28 mo	•Reduction in SRA results per 1000 admissions (3.7 vs 0.6). •Reduction in number of 50-mL argatroban bags used per 1000 admissions (18.8 vs 14.3).

AMS, anticoagulation management service; ELISA, enzyme-linked immunosorbent assay; EMR, electronic medical record; HIT, heparin-induced thrombocytopenia; OD, optical density; SRA, serotonin release assay.

^aConference abstract

^bMultiple publications on same data.