Research into the frequency of ADRs that lead to hospital admission vary depending on the study design and how the term adverse drug reaction is defined. Data from meta-analyses and systematic reviews suggest that the rate of admissions directly due to ADRs is 5%. (Wiffen et al, 2002, Edwards et al, 2000, Einarson et al, 1993). A large prospective observational study in Merseyside found 6.5% of admissions were due to ADRs (Pirmohamed et al, 2004). It is much more difficult to estimate the level of ADRs in the community as reporting is not as efficient and trials are more difficult to conduct but they are important and do cause problems to patients.

What’s The Evidence? ADRs

In the Merseyside study mentioned earlier, (Pirmohamed et al, 2004), the researchers found that of 18,820 hospital admissions, 1,225 or 6.5% were due to adverse drug reactions. In 80% of these the admission was due directly to the ADR with the most common reaction being gastric bleeding due to aspirin and non aspirin Non Steroidal Anti Inflammatory Drugs (NSAIDs). There were 28 deaths, again mainly due to gastric bleeding but renal failure and lithium toxicity due to co-administration with NSAIDs were also implicated. The study was conducted in NHS hospitals in Merseyside. The conclusion was that there was an additional cost to the NHS of the ADRs which led to considerable morbidity and mortality. It is accepted that NSAIDs and other drugs which can cause ADRs have a place in therapy but prescribers need to be cautious when using them in order to reduce the burden ADRs can have on the NHS and to patients. Most ADRs identified in the research were predictable from known pharmacology of the drugs and many represented known interactions. What are your thoughts at this point? There were a number of comments about the paper with the majority being very positive. Other studies confirmed the findings but one or two authors thought that the blame could not be put solely on doctors. Patients buy aspirin and NSAIDs such as ibuprofen at the supermarket or pharmacy and this was not highlighted in the study. Similarly the dose of aspirin was not included in the results. Overall, monitoring, gastric protection and caution with drugs and susceptible patients is essential.