Naranjo algorithm

From WikiMD's Wellness Encyclopedia

The Naranjo Algorithm, also known as the Naranjo Scale or Naranjo Nomogram, is a methodological tool conceptualized by Naranjo and his colleagues. Its primary function is to assess the likelihood of an Adverse Drug Reaction (ADR) being attributable to a drug as opposed to other potential factors.[1]

Purpose and Application[edit | edit source]

In clinical practice and research, distinguishing between genuine ADRs and symptoms stemming from other causes can be challenging. The Naranjo Algorithm facilitates this by providing a structured framework to:

  • Gauge the probability of a drug causing an ADR
  • Help healthcare professionals make informed decisions about medication safety
  • Support authors in peer reviews by verifying the validity of conclusions concerning ADRs[2]

Questionnaire[edit | edit source]

The questionnaire comprises ten questions, each designed to elicit information relevant to the causative role of the drug in the observed ADR.

  1. Previous Reports
Have there been previous conclusive reports on this reaction?
Yes (+1) | No (0) | Do not know/not done (0)
  1. Adverse Event Post-Drug Administration
Did the adverse event appear after the suspected drug was administered?
Yes (+2) | No (-1) | Do not know/not done (0)
  1. Improvement upon Discontinuation
Did the adverse reaction improve when the drug was discontinued or a specific antagonist administered?
Yes (+1) | No (0) | Do not know/not done (0)
  1. Reaction on Re-administration
Did the adverse reaction appear when the drug was readministered?
Yes (+2) | No (-1) | Do not know/not done (0)
  1. Alternative Causes
Could there be alternative causes for the reaction?
Yes (-1) | No (+2) | Do not know/not done (0)
  1. Reaction to Placebo
Did the reaction reappear when a placebo was given?
Yes (-1) | No (+1) | Do not know/not done (0)
  1. Toxic Concentrations
Was the drug detected in any body fluid in toxic concentrations?
Yes (+1) | No (0) | Do not know/not done (0)
  1. Reaction Severity with Dose Changes
Was the reaction more severe with increased dose or less severe with decreased dose?
Yes (+1) | No (0) | Do not know/not done (0)
  1. Previous Exposure
Did the patient have a similar reaction to the same/similar drugs in any previous exposure?
Yes (+1) | No (0) | Do not know/not done (0)
  1. Objective Evidence
Was the adverse event confirmed by any objective evidence?
Yes (+1) | No (0) | Do not know/not done (0)

Scoring[edit | edit source]

Based on the cumulative score derived from the questionnaire:

  • ≥ 9: Definite ADR
  • 5-8: Probable ADR
  • 1-4: Possible ADR
  • 0: Doubtful ADR

Significance and Limitations[edit | edit source]

While the Naranjo Scale provides a systematic approach to evaluating ADRs, like any tool, it has limitations. The questionnaire relies heavily on the subjective assessment and knowledge of the evaluator. Consequently, it is crucial to apply the Naranjo Algorithm within its intended context, understanding its strengths and constraints.[3]

References[edit | edit source]

  1. ↑ Naranjo CA, Busto U, Sellers EM, et al. A method for estimating the probability of adverse drug reactions. Clin Pharmacol Ther 1981;30:239-45.
  2. ↑ Agbabiaka TB, Savovic J, Ernst E. Methods for causality assessment of adverse drug reactions: a systematic review. Drug Saf 2008;31:21-37.
  3. ↑ Ribeiro-Vaz I, Santos CC, Cruz-Correia R. A method and a computational tool to assess drug causality in adverse drug reactions: pilot study. Drugs Real World Outcomes. 2018;5(1):47-55.

External links[edit | edit source]

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Contributors: Prab R. Tumpati, MD