hep_hit_score: HIT Expert Probability (HEP) Score

In cliot: Clinical Indices and Outcomes Tools

HIT Expert Probability (HEP) Score

Description

Calculates the HEP Score to estimate the pre-test probability of Heparin-Induced Thrombocytopenia (HIT). This expert-derived scoring system is more detailed than the 4Ts score and is often used to rule out HIT with high sensitivity.

Usage

hep_hit_score(platelet_fall_percent, timing_code, nadir_platelet_count,
              thrombosis_code, skin_necrosis, acute_systemic_reaction,
              bleeding, other_causes_present)

Arguments

platelet_fall_percent	Numeric. Percentage drop in platelet count (0-100). <30: -1 pt. 30-50: +1 pt. >50: +3 pts.
timing_code	Numeric. Code for timing of platelet fall relative to heparin exposure. 0: <4 days (first exposure). 1: Day 4. 2: Days 5-10. 3: Days 11-14. 4: >14 days. 5: Rapid onset (<48h) with recent exposure. 6: Rapid onset (>48h) with recent exposure.
nadir_platelet_count	Numeric. Lowest platelet count recorded (x 10^9/L). <=20: -2 pts. >20: +2 pts.
thrombosis_code	Numeric. 0=None, 1=New Thrombosis (+3 pts), 2=Progression of existing thrombosis (+2 pts).
skin_necrosis	Numeric (0 or 1). Skin necrosis at injection sites. (1 = Yes, +3 pts).
acute_systemic_reaction	Numeric (0 or 1). Acute systemic reaction to heparin bolus. (1 = Yes, +2 pts).
bleeding	Numeric (0 or 1). Presence of bleeding. (1 = Yes, -1 pt).
other_causes_present	Numeric (0 or 1). Presence of other causes for thrombocytopenia (e.g., sepsis, DIC, non-heparin meds). (1 = Yes, -2 pts; 0 = No, +3 pts).

Value

A list containing:

HEP_Score	The calculated total score.
Probability	Risk interpretation (High >= 2, Low < 2).

References

Cuker A, Arepally G, Crowther MA, et al. The HIT Expert Probability (HEP) Score: a novel pre-test probability model for heparin-induced thrombocytopenia based on broad expert opinion. J Thromb Haemost. 2010;8(12):2642-2650. doi:10.1111/j.1538-7836.2010.04059.x

Examples

# Example 1: High Probability
# Fall 60% (+3), Timing 7 days (2 -> +3), Nadir 50 (+2), New Clot (1 -> +3), No others (+3)
# Score = 14
hep_hit_score(60, 2, 50, 1, 0, 0, 0, 0)

# Example 2: Low Probability
# Fall 20% (-1), Timing <4d (0 -> -2), Nadir 10 (-2), Bleeding (1 -> -1), Other cause (1 -> -2)
# Score = -8
hep_hit_score(20, 0, 10, 0, 0, 0, 1, 1)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.