**4. Severity of adverse drug reactions – Fatal adverse drug reaction**

It has been estimated than fatal ADRs are expected in approximately 0.32% of hospitalized patients, and complications from drug therapy are the most common adverse event in hospitalized patients. If true, then ADRs are the 4th leading cause of death—ahead of pulmonary disease, diabetes, AIDS, pneumonia, accidents, and automobile deaths. However, some studies show greater severity prevalence and fatality rate. In the hospital setting the study from Kaurr, (Kaurr,2011) observed grade severe of adverse reaction in 13.4% patients. In the study from Sánchez Muñoz-Torrero (2010) the reactions were severe in 17% and fatal in 1.6% of hospitalized patients.

ADRs can be considered "on-target" effects, if they are result of exaggerated pharmacology that may be managed by dose reduction or other therapeutic modifications, i.e. hypoglycemia associated with antidiabetic agents. "Off-target" toxicities are frequently more problematic because they may not be predicted from pharmacology and toxicology studies, and they may occur only after prolonged exposure, i.e. hypersensibility reactions associated to antiepileptics. Unexpected ADRs that first appear after marketing authorization of the medication continue trouble clinicians, regulators, and drug sponsors. The most notably cause is the use by large number of patients, providing sufficient statistical power to detect rare events. Other factors include use in special populations, drug inte

ractions, renal and hepatic insufficiency, long duration of use and drug withdrawal.

Adverse drug reactions (ADRs) are considered to be among the leading causes of morbidity and mortality. Around 5-25% of hospitals admissions are estimated to be due to ADRs and about 6-15% of hospitalized patients experience serious ADRs (SADRs) causing significant prolongation of hospital stay and projected that adverse drug events are the fourth to sixth leading cause of death in the United States. Most studies are focused on rates of serious and fatal events in hospitalized patients, probably because tracking of ADRs is more established in the inpatients setting. An English study (Kane-Gill, 2010) found an increase in hospitalizations caused by ADR in about 76.8% in ten years. A recent study of administrative health-care data found an annual ADR prevalence rate of 0.5% among ambulatory-care patients; however, the authors acknowledge this is probably an underestimate of true ADR rates. Ambulatory-care patients experiencing an ADR were

Risk factors of suffering adverse drug events are: women, elderly and polipharmacy mainly. Women were more likely than men to have ADRs in both outpatients and inpatients settings. In the study from Zopf (2008), the OR of women from suffering ADR was 1.562; (95% CI 0.785, 2.013). Other risk factors implicated in adverse drug reactions are elderly, drug-drug interactions, polipharmacy and renal insufficiency. In the study of Sanchez Muñoz (2011), also drug-drug interactions were as important as age and renal insufficiency

Patients affected by adverse dug events are admitted in internal medicine department and geriatrics quite often, but patients hospitalized in Intensive care units and pediatrics also

It has been estimated than fatal ADRs are expected in approximately 0.32% of hospitalized patients, and complications from drug therapy are the most common adverse event in hospitalized patients. If true, then ADRs are the 4th leading cause of death—ahead of pulmonary disease, diabetes, AIDS, pneumonia, accidents, and automobile deaths. However, some studies show greater severity prevalence and fatality rate. In the hospital setting the study from Kaurr, (Kaurr,2011) observed grade severe of adverse reaction in 13.4% patients. In the study from Sánchez Muñoz-Torrero (2010) the reactions were severe

**4. Severity of adverse drug reactions – Fatal adverse drug reaction** 

**3. Epidemiology of adverse drug reactions** 

younger on average than hospitalized patients.

in 17% and fatal in 1.6% of hospitalized patients.

in producing adverse drug reactions.

suffer from these problems.

These statistics do not include the number of ADRs that occur in ambulatory settings. The exact number of ADRs is not certain and is limited by methodological considerations. However, whatever the true number is, ADRs represent a significant public health problem. In a Sweden study there were reviewed the death reports in one year in relation with adverse drugs reactions. They found 3.1% of deaths associated with fatal adverse drug events, mostly haemorraghes. 89% of patients died at hospital meanwhile only 35% of patients dead at hospital with no relation with drug events.

So most of studies trying to establish epidemiology and cost of adverse drug reactions demonstrate that these events are harmful and we have to make great efforts to diminish the incidence and morbidity.
