Pharmacovigilance PRR/ROR
Also known as: PRR, ROR, signal detection, adverse event monitoring
Proportional Reporting Ratio (PRR) and Reporting Odds Ratio (ROR) are statistical methods for detecting safety signals in spontaneous adverse event reporting databases. Developed and formalized by researchers in the early 2000s, these measures identify drug-adverse event associations that warrant further investigation.
Key highlights
- Signal detection at scale: screens millions of reports across thousands of drug-event pairs rapidly
- Established regulatory acceptance: PRR and ROR are standard methods used by EMA, FDA, and WHO-Uppsala
- No comparator drug needed for ROR: odds ratio formulation is symmetric and easy to interpret
- Early warning system: can detect novel safety signals before formal epidemiological studies are feasible
- Publicly available databases: FAERS and EudraVigilance provide large, continuously updated data sources
Intuition
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How it works
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When to use it
Use PRR and ROR for disproportionality analysis of spontaneous adverse event reporting databases (e.g., FDA FAERS, EudraVigilance) when screening for drug-adverse event signals — particularly in post-marketing pharmacovigilance where randomized trial data are unavailable or insufficient for rare events.
Strengths & limitations
- Signal detection at scale: screens millions of reports across thousands of drug-event pairs rapidly
- Established regulatory acceptance: PRR and ROR are standard methods used by EMA, FDA, and WHO-Uppsala
- No comparator drug needed for ROR: odds ratio formulation is symmetric and easy to interpret
- Early warning system: can detect novel safety signals before formal epidemiological studies are feasible
- Publicly available databases: FAERS and EudraVigilance provide large, continuously updated data sources
- Confounding by indication: drugs prescribed for specific diseases may show spurious associations with disease-related events
- Notoriety bias: media attention increases reporting of a specific drug-event pair, inflating signals
- Under-reporting: spontaneous reporting captures only an estimated 1–10% of actual adverse events
- No denominator: cannot calculate incidence rates; only relative reporting frequencies are available
- Masking: a dominant drug-event pair can suppress signals for co-reported drugs (pooled background effect)
Sources
- 1.Szarfman, A., Tonning, J. M., Doraiswamy, P. M., & Osgood, D. J. (2002). Pharmacovigilance in the post-marketing setting: establishing causal links between drugs and adverse events. Drug Safety, 25(9), 619-631.
- 2.van Puijenbroek, E. P., Bate, A., Leufkens, H. G., Lindquist, M., Orre, R., & Egberts, A. C. (2002). A comparison of measures of disproportionality for signal detection in spontaneous adverse drug reaction reporting. Pharmacoepidemiology and Drug Safety, 11(1), 3-10.
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ScholarGate. (2026, June 3). Pharmacovigilance PRR/ROR. ScholarGate. https://scholargate.app/pharmacology/pharmacovigilance-prr-ror