Monitoring ADRs: Need and methodes

Need for ADR monitoring: ADRs are responsible for significant morbidity and mortality and can adversely affect a patient’s quality of life. Studies have shown that ADRs are responsible for a significant number of hospital admissions, with reports ranging from 0.3% to as high as 11%. ADRs also have a significant impact on the healthcare costs. Studies have estimated that the occurrence of an ADR increased the cost of patient care by $2262 per patient.

Another study has estimated the cost of preventable ADRs in a 700 bed hospital to be $2.8 million per annum.

Severity Assessment of ADRs

Severity assessment of ADRs: The term severity is often used to describe the intensity of a medical event, as in grading ‘mild’, ‘moderate’ and ‘severe’. Severity assessment categorizes the ADRs as mild, moderate, or severe based on the based on the steps taken for the management of the ADRs.

Karch and Lasagna classified severity into minor, moderate, severe and lethal as defined below:

i. Minor: no antidote, therapy or prolongation of hospitalization required. 

ii. Moderate: requires a change in drug therapy, specific treatment or an increase in hospitalization by at least 1 day.

iii. Severe: potentially life threatening, causing permanent damage or requiring intensive medical care.

iv. Lethal: directly or indirectly contributes to the death of the patient.

Causality assessment of ADRs

Causality assessment of ADRs

Determining which adverse event is caused by drugs with reasonable certainty is an essential though difficult part of documenting ADRs. The development of a symptom or detrimental outcome while taking a medication does not establish the drug as the cause of the injury. Likewise, development of an event or a disease remotely in time from the use of a drug does not exonerate the therapy from being the source of the problem. In order to initiate appropriate measures to prevent further occurrence of ADRs, it is necessary to identify the causative drug. This can be done by carrying out the causality assessment of the suspected drug. Causality assessment is carried out to establish a causal relationship between a drug and ADR.

ADRs: Predisposing factors

Factors predisposing to ADRs may relate either to the properties of the drug or to the characteristics of the individual. Different factors predisposing to ADRs are discussed below:

Classification of Adverse Drug Reactions

There are several ways of classifying ADRs. The simplest one is that proposed by Rawlins and Thompson which was later modified by Wills and Brown.

I. Rawlins and Thompson classification: In this classification, the ADRs are categorized into two classes viz type A and type B reactions.

Adverse Drug Reactions (ADR)

ADVERSE DRUG REACTIONs (ADRs)

It has been recognized since the earliest times and now universally accepted that no drug is free from side effects and that drug therapy itself can be a significant cause of morbidity and mortality.

Definition of adverse drug reaction (ADR)  
An ADR is basically any undesirable effect of a drug beyond its anticipated therapeutic effects occurring during clinical use.

Several definitions of ADR exist in literature, including those of World Health Organization (WHO), Karch and Lasagna, American Society of Health- system Pharmacists (ASHP), and United States Food and Drug Administration (USFDA).