Incidence of Adverse Drug Reactions in Hospitalized Patients – A Meta-analysis of Prospective Studies

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:   Frankp@chiro.org

FROM:   JAMA 1998 (Apr 15);   279 (15):   1200–1205

Jason Lazarou, MSc; Bruce H. Pomeranz, MD, PhD; Paul N. Corey, PhD


NOTE: This abstract mentions no numbers in it's text, but the body of the article states “that more than 2 million Americans become seriously ill every year from reactions to drugs that were correctly prescribed and taken, and that 106,000 Americans die annually from those side effects.” (emphasis added)   A related JAMA Editorial in the same issue also states that “ADRs may be the fourth to sixth leading cause of death, and that drug-related injuries occur in 6.7% of hospitalized patients.”

A review of this paper by the AHRQ states:
The authors report a meta-analysis of 32 years of prospective studies on adverse drug reactions (ADRs). The study specifically excludes medication ordering or administration errors, focusing instead on drug toxicity, allergic reactions, and idiosyncratic adverse reactions. The authors estimate an overall incidence of 6.7% for serious ADRs in hospitalized patients and 0.32% for fatal ADRs. Using 1994 as a representative year, the authors calculate an estimated 2,216,000 serious ADRs in the United States for that year, with 106,000 fatalities, an estimate that would make ADRs between the fourth and sixth leading causes of death in the United States.


Objective:   To estimate the incidence of serious and fatal adverse drug reactions (ADR) in hospital patients.

Data Sources:   Four electronic databases were searched from 1966 to 1996.

Study Selection:   Of 153, we selected 39 prospective studies from US hospitals.

Data Extraction:   Data extracted independently by 2 investigators were analyzed by a random-effects model. To obtain the overall incidence of ADRs in hospitalized patients, we combined the incidence of ADRs occurring while in the hospital plus the incidence of ADRs causing admission to hospital. We excluded errors in drug administration, noncompliance, overdose, drug abuse, therapeutic failures, and possible ADRs. Serious ADRs were defined as those that required hospitalization, were permanently disabling, or resulted in death.

Data Synthesis:   The overall incidence of serious ADRs was 6.7% (95% confidence interval [CI], 5.2%-8.2%) and of fatal ADRs was 0.32% (95% CI, 0.23%-0.41%) of hospitalized patients. We estimated that in 1994 overall 2216000 (1721000-2711000) hospitalized patients had serious ADRs and 106000 (76000-137000) had fatal ADRs, making these reactions between the fourth and sixth leading cause of death.

Conclusions:   The incidence of serious and fatal ADRs in US hospitals was found to be extremely high. While our results must be viewed with circumspection because of heterogeneity among studies and small biases in the samples, these data nevertheless suggest that ADRs represent an important clinical issue.

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