adverse drug reaction (ADR)

Introduction

A harmful or inpleasant reaction resulting from an intervention related to a medicinal product, which predicts hazard of future administration & warrants prevention &/or specific treatment, alteration of drug dosage or discontinuation of a drug.

Etiology

• risk factors
  • number of drugs (> 4)
  • heart failure
  • liver disease
  • multiple medical problems (4-6 or more)
  • renal failure
  • older age
  • lower body weight or lower body mass index
  • prior adverse drug reaction

Epidemiology

• 0.4% of people/year visit emergency departments (ED) for adverse drug events (ADE)
  • 25% result in hospitalization
  • 1% of elderly visit ED for ADE
    • almost 50% are hospitalized
• 1.5-5% of hospital admissions
• 6.7% of hospitalized patients
• few anecdotal reports of adverse drug reactions later corroborated
• four medications account for 2/3 of drug-related emergency department visits & hospitalizations in the elderly
  • anticoagulants, especially warfarin (33%)
  • insulins (14%) & oral hypoglycemics (11%)
  • antiplatelet agents (13%)
  • opioids
• Beer's criteria meds account for < 4% of elderly patient emergency department visits for adverse drug events

Complications

• prolongation of hospitalization
• morbidity & mortality
• drug-induced systemic reactions can last for weeks after stopping offending drug

Management

• stop offending drug
• systemic glucocorticoids for systemic drug reactions
  • may be needed for months

Notes

• see drug adverse effect or the drug itself for adverse effects of a specific drug or classes of drug
• as a general rule, the drug would need to be administered at >= 3x the frequency of the adverse drug event to observe 1 event with 95% confidence; thus if frequency is 1%
  • probability of observance = 1 - (1 - frequency) exp (number of participants)
    • if 100 participants,
      • probability of observance = 1 - (1 - 0.01) exp 100 = 0.63

More general terms

• adverse effect

More specific terms

• adverse cutaneous drug reaction
• drug eruption; drug rash
• drug-induced fever
• drug/toxin-induced hepatitis
• NSAID enterocolopathy
• NSAID gastropathy
• serum sickness; serum sickness-like reaction
• type A drug reaction
• type B drug reaction; drug-induced hypersensitivity syndrome; drug rash with eosinophilia & systemic symptoms (DIHS, DRESS)

Additional terms

• drug adverse effect(s)