The Naranjo algorithm, Naranjo Scale, or Naranjo Nomogram is a questionnaire designed by Naranjo ''et al.'' for determining the likelihood of whether an ADR ( adverse drug reaction) is actually due to the

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

rather than the result of other factors. Probability is assigned via a score termed definite, probable, possible or doubtful. Values obtained from this algorithm are often used in peer reviews to verify the validity of author's conclusions regarding adverse drug reactions. It is also called the Naranjo Scale or Naranjo Score. It is often compared to the WHO- UMC system for standardized causality assessment for suspected adverse drug reactions (ADRs). Empirical approaches to identifying ADRs have fallen short because of the complexity of the set of variables involved in their detection. Computer decision programs have helped in this analysis. Electronic medical record systems can be programmed to fire alerts when a potential adverse drug event is about to occur or has already occurred. ,4Automated adverse drug event monitors can search for

keywords Keyword may refer to: Computing * Keyword (Internet search), a word or phrase typically used by bloggers or online content creator to rank a web page on a particular topic * Index term, a term used as a keyword to documents in an information syste ...

or phrases throughout the patient's medical record to identify drug therapies,

laboratory results A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physicia ...

, or problem lists that may indicate that a patient has already been treated for an ADR. This detection method uncovers significantly more adverse events, including medication errors, than relying on empirical methods or incident reports. ,2

Empirical Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...

methods to assess the likelihood that an ADR has taken place have been lacking. More formal, logical analysis can help differentiate between events that are attributable to a drug from those associated with underlying diseases or other factors, underlying the complexity of detection. Several investigators, among them researchers at the FDA, have developed such logical evaluation methods, or algorithms, for evaluating the probability of an ADR. , 20-24Almost all of these methods employ critical causation variables identified by Sir Austin Bradford Hill in 1965. The most widely accepted of these instruments is the Naranjo algorithm 2(Table). This method has been tested for internal validity with between-rater reliability testing, and its probability scale has consensual, content, and concurrent validity as well as ease of use in clinical settings and

controlled studies A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable (i.e. confounding variables). This increases the reliability of the results, often through a comparison betwe ...

Questionnaire

1. Are there previous conclusive reports on this reaction?

2. Did the adverse events appear after the suspected drug was given?

3. Did the adverse reaction improve when the drug was discontinued or a specific antagonist was given?

4. Did the adverse reaction appear when the drug was readministered?

5. Are there alternative causes that could have caused the reaction?

6. Did the reaction reappear when a placebo was given?

7. Was the drug detected in any body fluid in toxic concentrations?

8. Was the reaction more severe when the dose was increased, or less severe when the dose was decreased?

9. Did the patient have a similar reaction to the same or similar drugs in any previous exposure?

10. Was the adverse event confirmed by any objective evidence?

Scoring * ≥ 9 = definite ADR * 5-8 = probable ADR * 1-4 = possible ADR * 0 = doubtful ADR

References

* {{Cite journal, last1=Naranjo, first1=C A, last2=Busto, first2=U, last3=Sellers, first3=E M, last4=Sandor, first4=P, last5=Ruiz, first5=I, last6=Roberts, first6=E A, last7=Janecek, first7=E, last8=Domecq, first8=C, last9=Greenblatt, first9=D J, date=1981, title=A method for estimating the probability of adverse drug reactions, journal=Clinical Pharmacology and Therapeutics, volume=30, issue=2, pages=239–245, doi=10.1038/clpt.1981.154, pmid=7249508, s2cid=29728085 , issn=0009-9236 A*l-Tajir GK, Kelly WN. Epidemiology, comparative methods of detection, and preventability of adverse drug events. Ann Pharmacother. 2005;39:1169-1174. Abstract *Brown S, Black K, Mrochek S, et al. RADARX: recognizing, assessing, and documenting adverse Rx events. Proc AMIA Symp. 2000:101-105. *Classen DC, Pestotnik SL, Evans RS, et al. Description of a computerized adverse drug event monitor using a hospital information system. Hosp Pharm. 1992;27:774-783. Abstract *Gandi TK, Bates DW. Computer adverse drug event detection and alerts. In: Making Healthcare Safer: A Critical Analysis of Patient Safety Practices. Rockville, Md: Agency for Healthcare Research and Quality; 2001. *Jones JK. Adverse drug reactions in the community health setting: approaches to recognizing, counseling, and reporting. Fam Community Health. 1982;5:1982. *Hill AB. The environment and disease association or causation. Proc R Soc Med. 1965;58:295-300. Abstract *Naranjo CA, Busto U, Sellers EM, et al. A method for estimating the probability of adverse drug reactions. Clin Pharmacol Ther. 1981;30:239-245. Abstract

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