What is the role of steroids, such as prednisone, in preventing biphasic anaphylactic reactions?

Role of Steroids in Preventing Biphasic Anaphylactic Reactions

Steroids are not recommended for the prevention of biphasic anaphylactic reactions as there is insufficient evidence supporting their effectiveness for this purpose. 1

Current Evidence on Steroids for Biphasic Anaphylaxis Prevention

The 2020 Joint Task Force Practice Parameter (JTFPP) on anaphylaxis management provides the most authoritative guidance on this topic. After systematic review of available evidence, they found:

• Glucocorticoids showed no significant benefit in preventing biphasic anaphylaxis (OR 0.87; 95% CI, 0.74-1.02) 1
• At a biphasic anaphylaxis prevalence of 5%, the number needed to treat (NNT) with glucocorticoids to prevent one case is 161 1
• In children, glucocorticoids may actually increase the risk of biphasic anaphylaxis (OR 1.55; 95% CI, 1.01-2.38) 1

The evidence quality for all these findings was rated as "very low" due to:

• Risk of bias across studies (lack of blinding, lack of randomization)
• Inconsistency in results
• Imprecision (wide confidence intervals)
• Potential confounding by severity of presentation

First-Line Management of Anaphylaxis

The management algorithm for anaphylaxis should prioritize:

1. Epinephrine administration - This remains the definitive first-line treatment for anaphylaxis 2

   • Intramuscular injection into the vastus lateralis at 0.01 mg/kg (1:1000 concentration)
   • Maximum single dose: 0.5 mg for adults >50 kg
   • May be repeated every 5 minutes as needed

2. Delayed epinephrine administration is associated with:

   • Increased anaphylaxis fatalities
   • Higher risk of biphasic reactions 1, 2

Secondary Therapies

After epinephrine administration, secondary therapies may include:

• H1 antihistamines (e.g., diphenhydramine 25-50 mg)

  • Primarily address cutaneous symptoms (urticaria, pruritus)
  • Not life-saving interventions 1
  • No significant benefit in preventing biphasic anaphylaxis (OR 0.71; 95% CI, 0.47-1.06) 1

• H2 antihistamines (e.g., ranitidine 50 mg)

  • No evidence of benefit in preventing biphasic anaphylaxis (OR 1.21; 95% CI, 0.80-1.83) 1
  • May be used in combination with H1 antihistamines 1

• Glucocorticoids

  • Slow onset of action (4-24 hours) makes them ineffective for acute anaphylaxis management 1, 3
  • No clear evidence supporting their use to prevent biphasic reactions 4, 5

Risk Factors for Biphasic Reactions

Factors associated with increased risk of biphasic reactions include:

• Severe initial anaphylactic reaction 1, 6
• Requirement for multiple doses of epinephrine (OR 4.82; 95% CI: 2.70,8.58) 1
• Delayed administration of epinephrine 1, 2
• History of drug anaphylaxis (OR 14.3,95% CI 2.4-85.8) 7

Observation Period and Follow-up

• Patients should be observed until signs and symptoms have fully resolved 1
• Extended observation (6+ hours) or hospital admission should be considered for:
  • Severe initial reactions
  • Patients requiring multiple epinephrine doses 1, 2
• Biphasic reactions can occur up to 72 hours later (mean 11 hours) 1
• All patients should be educated about the possibility of biphasic reactions 1

Common Pitfalls in Anaphylaxis Management

1. Delaying epinephrine administration while administering secondary medications like antihistamines or steroids
2. Overreliance on steroids for preventing biphasic reactions despite lack of evidence
3. Inadequate observation periods after apparent resolution of symptoms
4. Failure to provide patient education about potential biphasic reactions and when to seek emergency care

In conclusion, while steroids are commonly administered during anaphylaxis management, they should not be relied upon to prevent biphasic reactions. Early epinephrine administration remains the most important intervention both for treating the initial anaphylactic episode and potentially reducing the risk of biphasic reactions.