Agreement of stall-side and laboratory major crossmatch tests with the reference standard method in horses

J Vet Intern Med. 2020 Mar;34(2):941-948. doi: 10.1111/jvim.15710. Epub 2020 Feb 4.


Background: Crossmatching is used to prevent life-threatening transfusion reactions in horses. Laboratory methods are laborious and technically challenging, which is impractical during emergencies.

Hypothesis/objectives: Evaluate agreement between a stall-side crossmatch kit (KIT) and a laboratory method (LAB) in horses with known and unknown blood types.

Animals: Twenty-four blood-typed and alloantibody-screened healthy adult horses (Aim 1) and 156 adult horses of unknown blood type (Aim 2).

Methods: Prospective, blinded study. Expected positive (n = 35) and negative (n = 36) crossmatches among 24 antibody and blood-typed horses were used to determine sensitivity and specificity of KIT and LAB against the reference method. Agreement in 156 untyped horses was evaluated by reciprocal crossmatch (n = 156).

Results: Sensitivity (95% confidence interval [CI]) for LAB and KIT compared with expected reactions was 77.1% (59.9%-90.0%) and 91.4% (77.0%-98.2%), and specificity 77.8% (60.9%-89.9%) and 73.5% (55.6%-87.1%), respectively. The KIT was 100% sensitive for Aa reactions; LAB was 100% sensitive for Qab; and both were 100% sensitive for Ca. Cohen's κ agreement for LAB and KIT with expected positive and negative reactions (n = 71) was moderate (0.55 [0.36-0.74]) and substantial (0.65 [0.47-0.82]), respectively. Agreement was fair comparing LAB with KIT in Aim 1 (0.30 [0.08-0.52]) and in untyped horses in Aim 2 (0.26 [0.11-0.41]).

Conclusions and clinical importance: Agreement between KIT and LAB with expected reactions was blood type dependent. Performance of both methods depends on blood type prevalence.

Keywords: agglutination; alloantibody; blood incompatibility; blood type; point-of-care test; transfusion reaction.

Publication types

  • Evaluation Study

MeSH terms

  • Animal Husbandry*
  • Animals
  • Blood Grouping and Crossmatching / veterinary*
  • Blood Transfusion / veterinary
  • Female
  • Horses / blood*
  • Male
  • Point-of-Care Systems*
  • Prospective Studies
  • Sensitivity and Specificity