Scientific Poster Session III - Original Research

Original Research
  Monday, October 14, 2024
  01:00 PM–02:30 PM

Abstract

Introduction:The ideal dosing weight metric for enoxaparin remains elusive. Dosing remains focused on actual body weight, which may inadvertently increase the risk of bleeding in those with obesity, while the use of ideal weight may relatively underdose those with obesity.

Research Question or Hypothesis: determine the optimal obesity-adjusted enoxaparin dosing weight

Study Design: Retrospective data was collected across five metropolitan hospitals over a 2-year period.

Methods: Eligible subjects had minimum 48 hours of in-hospital twice-daily enoxaparin and Factor anti-Xa level 3-5 hours post-dose (n=220). Multiple linear regression calculated the degree of associated variance between a range of nominal dosing weights and Factor anti-Xa levels, adjusted for renal function. Dosing weights were calculated as ideal body weight (IBW) and then incrementally adjusted for increasing percentages of weight above IBW ie IBW+10% above IBW, IBW+20% etc up to actual body weight. Likewise, dosing weights were also tested using lean body weight (LBW).

Results:

For BMI>30kg/m² optimal variance explained by dosing weight metrics was at IBW+40% (23%) and similarly for LBW+40% (23%). Use of actual body weight (ABW) to calculate doses had lowest associated variance with Factor anti-Xa levels (18%) followed by unadjusted IBW (13%) or unadjusted LBW (19%). In those with BMI<30kg/m² there was similar explained variance in the ranges of IBW+20-50% and LBW 10-40% (21%).

Conclusion: Compared to IBW+40% or LBW+40% use of ABW to calculate dose was poorly associated with Factor anti-Xa levels, as was IBW or LBW when unadjusted for obesity. IBW+40% and LBW+40% requires further prospective study and may offer a more consistent Factor anti-Xa response on the background of increasing obesity and bleeding risk profiles.

Presenting Author

Gregory Roberts BPharm
Flinders Medical Centre

Authors

Anthony Damiani BPharm
SA Pharmacy

Viviane De Menezes Caceres BPhysio
SA Health

Patrick Russell MD
SA Health

Nicholas Scarfo BPharm
SA Pharmacy

Des Williams PhD
University of South Australia