DETECTION OF ADVERSE DRUG EVENTS

There are three types of surveillance systems that may be used to detect ADRs:

1. Prospective

2. Concurrent

3. Retrospective

Identifying which methods to use will depend on the unique characteristics of a facility. However, ADRs are more likely to be detected when a combination of surveillance systems are used. It should be noted that the success of any surveillance system depends on the willing participation of healthcare professionals in reporting ADRs.

PROSPECTIVE SURVEILLANCE SYSTEM

Prospective surveillance occurs prior to initiation of medication therapy and can be accomplished in two ways:

1. Monitoring of patients who are at a high risk for experiencing ADRs—Risk factors for ADRs include the following:

• Polypharmacy

• Extremes of age (e.g., neonatal, pediatric, and geriatric patients)

• Presence of concurrent disease states (e.g., impaired renal or hepatic function)

• Severity of illness

• History of allergy/previous ADR

• Pharmacodynamic/pharmacokinetic changes

2. Monitoring of patients who are receiving medications known to have a high potential for causing ADRs—The drug classes most frequently implicated in ADRs include the following:

• Anticoagulants (e.g., heparin, warfarin etc)

• Antimicrobials (e.g., penicillins, cephalosporins, sulfonamides, aminoglycosides etc)

• Anti-Cancer agents

• Cardiac agents (e.g., antiarrhythmics, digoxin, diuretics, antihypertensives etc )

• Central nervous system (CNS) agents (e.g., analgesics, anticonvulsants, sedatives/ hypnotics etc)

• Diagnostic agents (e.g., contrast media)

• Antidiabetics (including insulin)

• Corticosteroids

CONCURRENT SURVEILLANCE SYSTEM

Concurrent surveillance involves the identification of ADRs close to the time they occur. There are several methods that can be used to detect ADRs concurrently:

• Spontaneous reporting of ADRs by primary care practitioners (such as physicians and nurses) during the course of their work using telephone hotlines, ADR alert cards, report forms, etc.

• Analysis of medication usage evaluation (MUE) studies

• Reporting of suspected ADRs by hospital utilization review/quality assurance personnel from their concurrent review of patient charts

• Monitoring of orders and patient charts by pharmacy personnel for clues (often called triggers) that an ADR has occurred

• Concurrent surveillance has the advantage of allowing a more thorough investigation because the patient, nurse, and physician are available for interviews and are likely to recollect events more accurately. Also, this method allows interventions and management of the ADR to take place in a timely manner.

RETROSPECTIVE SURVEILLANCE SYSTEM

Retrospective surveillance involves the review of medical records for adverse drug reactions. It is not a desirable approach to monitor ADRs because of the disadvantages inherent in utilizing retrospective data. These disadvantages include

· Inadequate documentation of events on medical records and

· The inability to intervene.

A trigger is defined as an occurrence, prompt or flag found on review of the medical record that “triggers “further investigation to determine the presence or absence of an adverse event”. A trigger may include laboratory trigger, medical trigger and clinician trigger.

Triggers include the following:

• Abnormal test results such as serum drug concentrations above therapeutic levels and laboratory test results outside a particular range or threshold (e.g., platelet count less than 50,000)

• Alerting order, which is an order or sequence of orders that suggests an adverse effect may have taken place

Alerting orders include the sudden discontinuation of one or more medications, an unexpected reduction in dosage, and a stat order for an antidote or other medication used to manage ADRs, such as the following:

• Atropine

• Phytonadione (vitamin K)

• Benzotropine

• Potassium chloride

• Dextrose 50%

• Flumazenil

• Glucagon

• Protamine

• Naloxone

• Nitroglycerin

• Diphenhydramine

• Physostigmine

• Epinephrine

• Sodium polystyrene sulfonate (SPS)

• Furosemide

• Antidiarrheals

• Antiemetics

• Glucocorticosteroids

Alerting orders also include non-routine orders for laboratory tests, such as the following:

• BUN

• Serum creatinine

• AST,ALT

• Urine protein, cells, casts

• PT,PTT, Platelet count

• Drug serum concentration

• Clostridium difficile