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Abstract: FR-PO067

Platelet Factor 4 Antibodies and Severe AKI

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology‚ Risk Factors‚ and Prevention

Authors

  • Thomas, Charlotte, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Ali, Rafia W., Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Park, Isabel, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Kim, Helena, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Short, Samuel, University of Vermont College of Medicine, Burlington, Vermont, United States
  • Al-Samkari, Hanny, Massachusetts General Hospital, Boston, Massachusetts, United States
  • Leaf, David E., Brigham and Women's Hospital, Boston, Massachusetts, United States
Background

Production of platelet factor 4 (PF4) antibodies is the seminal event in the development of heparin-induced thrombocytopenia, a common and often devastating complication in hospitalized patients. PF4 antibodies can cause macrovascular arterial and venous thrombosis, however, only limited data are available on their association with microvascular thrombosis. Since the kidney is a highly vascularized organ, and renal microvascular thrombosis has been observed in multiple kidney diseases, we hypothesized that the appearance of PF4 antibodies in the circulation is independently associated with a higher risk of development of severe acute kidney injury (AKI) among hospitalized patients.

Methods

We performed a retrospective cohort study of all adult inpatients who had a PF4 test during an admission to two large academic hospitals in Boston, MA, between 2015 and 2021. Data were extracted using ICD-9/10 diagnosis and procedure codes. The primary exposure was a positive PF4 antibody immunoassay test. The primary outcome was severe AKI, defined as ≥200% increase in serum creatinine compared to the hospital admission value or receipt of kidney replacement therapy within 7 days following the PF4 test. We used multivariable logistic regression to adjust for potential confounders.

Results

The cohort consisted of 4224 patients who had a PF4 test, of whom 469 (11.1%) tested positive. Among those with a positive PF4 test, 50 (10.7%) developed severe AKI compared to 235 (6.3%) with a negative test (P<0.001). In a multivariable model adjusted for age, sex race, baseline eGFR, comorbidities, and severity of illness, patients with a positive PF4 test had 51% higher odds of developing severe AKI (95% CI, 1.08–2.13) compared to patients with a negative test (Figure). Patients with a positive PF4 test also had higher risk of developing AKI (any stage), the composite of AKI or death, and arterial and venous thrombosis, with similar magnitudes of association seen with thrombosis as with AKI (Figure).

Conclusion

PF4 positivity is independently associated with a higher risk of severe AKI in hospitalized patients.