A retrospective study of antivenom-associated adverse reaction and anaphylaxis at Ngwelezana Hospital, South Africa

Abstract

BackgroundSnakebite victims are commonly seen in KwaZulu-Natal Hospitals, with only a minority of patients requiring antivenom. This study reviewed antivenom-associated adverse events at our institution, after administration of the South African Vaccine Producers (SAVP) polyvalent antivenom. MethodsA retrospective review, over 52 months (January 2016–April 2020), of patients who received antivenom. Demographics, clinical details and clinical course following antivenom administration were analysed. ResultsEmergency department doctors treated 758 snakebites; 156 patients were admitted of which 51 (33%) received antivenom. Indications for antivenom included: neurotoxicity (24%), haemotoxicity (18%) and significant cytotoxicity (58%). Antivenom-associated adverse events occurred in 61% of patients; with 47% developing anaphylaxis requiring adrenaline infusion. There was a higher incidence of anaphylaxis in children (57%) than in adults (40%), p = 0.55. There was no association between antivenom dose and anaphylaxis. No benefit was noted with adrenaline premedication (p = 0.64), nor with the addition of antihistamine or steroid pre-medicants to adrenaline (p = 0.61). Multivariable logistic regression identified age as a predictor for anaphylaxis, but not dose or duration of antivenom and not any particular form of premedication. Intubation was required in 29% of patients developing anaphylaxis. There were no deaths and all patients made full recovery. ConclusionAlmost half of the patients at Ngwelezana hospital in Kwazulu-Natal receiving the SAVP polyvalent antivenom developed anaphylaxis requiring adrenaline infusion, with children at higher risk. The administration of this antivenom must only be given for valid indications, in a high-care environment by medical personnel ready to manage anaphylactic shock. The addition of antihistamine and corticosteroids to adrenaline for premedication has no added benefit.