Table 2. List of unique outcomes identified in systematic review and summary information.

Outcome area	Outcome summary
Mortality	Death was measured as all-cause mortality, survival, or cause-specific mortality
Life Impact Outcome	1. Functional life impact: Patient Specific Functional Scale, and the physical function domain of the SF-36 questionnaire 2. Disability: Sheehan Disability Inventory and American Medical Association (AMA) disability rating score. 3. Quality of life: Patient's Global Impression of Change Scale, Clinical Global Impression - Improvement (CGI-I), and Patient-reported outcome measurement information system physical function-10 score (PROMIS PF-10). 4. Time to functional recovery: defined as time to full functional status recovery as measured by the Patient-Specific Functional Scale, or complete resolution of swelling and ability to run and jump (for lower extremity bites) or equal hand-grip (for upper extremity bites). 5. Lower extremity function: Scores on Lower Extremity Functional Scale, and walking speed. 6. Upper extremity function: Scores on the Disorders of the Arm, Shoulder, and Hand (DASH) and grip strength through a dynamometer.
Resource use outcome	Hospital 1. Duration of hospital stay: no clear criterion for discharge except in one study. 2. Duration of Intensive Care Unit (ICU) stay: no clear criterion.
	Need for further intervention 1. Requirement of a blood product (unspecified or any). 2. Requirement of FFP (fresh frozen plasma). 3. Requirement of PRBC (packed red blood cell). 4. Requirement of platelets. 5. Requirement of cryoprecipitate. 6. Requirement of mechanical ventilation. 7. Requirement for non-invasive ventilation or reintubation (Post- extubation). 8. Requirement of antibiotic. 9. Requirement of analgesic. 10. Requirement of dialysis/renal replacement therapy. 11. Requirement of antivenom.
	Economic 1. Cost of antivenom (average compared). 2. Any cost-related outcome.
Adverse event/effect	1. Adverse event unclassified: proportion and time from antivenom infusion to reaction with or without classification of severity or frequency/proportion of treatment emergent adverse event. 2. Anaphylaxis: incidence and time from antivenom infusion to anaphylaxis with or without classification (Brown 2004 criterion) of severity. 3. Anaphylactoid syndrome: incidence of anaphylactoid syndrome, pyrogenic reaction alone and urticaria alone. 4. Early antivenom reaction (EAR): incidence and time from antivenom infusion to EAR. 5. Late antivenom reaction: incidence. 6. Adverse events specific to FFP: incidence. 7. Capillary leak syndrome: incidence.
Physiological/Clinical	Eye 1. Conjunctival oedema.
	Cardiac 1. Cardiac rhythm abnormalities. 2. Hypotension. 3. Shock.
	Psychiatric 1. Anxiety: Hopkins somatic symptoms checklist. 2. Depression: modified Sinhala version of the Beck depression inventory. 3. Post-Traumatic Stress Disorder: Post-traumatic Stress Symptom Scale-Self Report Scale. 4. Suicidal ideation and behaviour: Columbia-Suicide Severity Rating.
	Respiratory, thoracic and mediastinal 1. Respiratory distress: measured as airway obstruction, respiratory failure, and acute respiratory distress syndrome; no specific definition reported. 2. Negative inspiratory pressure: standard methods. 3. Forced vital capacity: standard methods.
	Neurological 1. Paralysis: proportion or duration; assessed clinically, no clear definition. 2. Ophthalmoplegia/Ptosis: days for resolution of ptosis/ophthalmoplegia, endurance of upward gaze, and proportion of the iris uncovered. 3. Anosmia: as reported by patient. 4. Motor strength: no clear definition. 5. Neurotoxicity overall: incidence/frequency and time to complete resolution of all neuroparalytic features.
	Injury/Poisoning 1. Venom concentration: standard methods. 2. Anti-venom concentration: standard methods. 3. Varisyllabic-methyl levels: standard methods.
	Immunological 1. Immunogenicity profile: standard methods. 2. profile of antibodies: standard methods. 3. COVIP-Plus induced sera: standard methods.
	General 1. Pain: intensity measured by Visual Analogue Scale, time for complete resolution of the local pain with or without induration. 2. Non-specific systemic symptoms: no definition provided.
	Musculoskeletal 1. Myotoxicity as an outcome was measured clinically, levels of creatine kinase, and levels of lactate dehydrogenase, creatine phosphokinase, metalloproteinases.
	Skin and subcutaneous 1. Necrosis: assessed clinically, no clear definition. 2. Blistering: assessed clinically, no clear definition. 3. Oedema: measured as circumference difference between the affected limb and the normal limb; circumference measurements of the affected limb alone; remission time of limb swelling; cessation of local swelling progression; time to swelling resolution; oedema progression; measurement of decrease of oedema-scaled dish. 4. Swelling: measured based on the number of segments affected (extent) and increase in circumference of the bitten limb (intensity); proximal length of swelling from bite site; criteria developed by Warell et al 1977; criteria based on physical appearance of swelling; swelling is confirmed to bitten segment or crosses 1 or 2 joints; and % increase in volume compared to contralateral (non-envenomated) limb. 5. Wound cosmesis: measured by any validated cosmesis score. 6. Any other wound related outcome, including but not limited to cosmesis.
	Infection, Infestation, and Inflammation 1. Abscess. 2. Blister. 3. Cellulitis. 4. Inflammatory markers. 5. Pneumonia. 6. Ventilator associated pneumonia. 7. Wound infection.
	Kidney and Urinary Outcomes 1. Blood urea nitrogen (BUN) and creatinine levels measures in serum. 2. Acute Kidney Injury defined as per Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) Criteria, Kidney Disease Improving Global Outcomes (KDIGO) Criteria, measurement of surrogate markers (Neutrophil gelatinase-associated lipocalin, beta2-microglobulin, Kidney Injury Molecule-1, serum creatinine), estimated glomerular filtration rate and oliguria. 3. Abnormalities in urine: proteinuria or haematuria. 4. Chronic kidney disease: no definition provided. 5. Renal angle tenderness: no definition provided. 6. Ferryl-haem derivatives: detected in urine sample.
	Blood and lymphatic system 1. Blood coagulability -by 20 min whole blood clotting test (WBCT20)/Lee -White method, or standard laboratory measures of international normalized ratio (INR), bleeding time (BT), clotting time (CT), Prothrombin Time (PT), aPTT (activated partial thromboplastin time). 2. Platelet count- standard laboratory measures. 3. Clotting Factors- Clotting factor panel or specific factors like fibrinogen, Factor V, VII, VIII, Fibrinogen degradation products/D-dimer. 4. Bleeding – defined clinically using various criterion. 5. Clot Quality- measures as per a method developed by Reid 6. Other Haematological parameters – complete blood count, packed cell volume. 7. Lymphadenopathy/lymphadenitis – no clear clinical criteria provided.
Composite Outcome	1. Clinical recovery as a composite outcome: seven unique definitions were used. 2. Complications as a composite outcome: four different definitions were used or not clearly reported. 3. Envenoming manifestations: measured compositely as improvement in signs and symptoms of envenoming (systematic alone or together with local). 4. Snakebite Severity Score (SSS): either the complete SSS or the pulmonary, cardiovascular, hematologic symptoms, and nervous system sub scores of the SSS, and as defined in the US FDA-approved information for Crotaline Polyvalent Immune Fab antivenom (FabAV) prescription. 5. Haemolysis: measured using haemolysis markers (visual haemolysis score level and abnormal lactate dehydrogenase - LDH levels). 6. Local Inflammation: Reduction in local inflammatory manifestations such as pain, oedema, and temperature (flushing). 7. Prognosis: no clear definition. 8. Treatment failure: measured as a composite outcome based on clinical features.