Pharmacoepidemiology in Pharmacy Practice

• This chapter discusses the incorporation of evidence-based medicine into clinical practice.

• Other areas to which pharmacists apply pharmacoepidemiological methods include: – adverse drug reaction surveillance – drug utilization evaluations (DUEs) – pharmacoeconomical analyses

• All of these functions provide pharmacists with excellent sources of data to conduct more formalized pharmacoepidemiological research.

Evidence-Based Medicine

• The best drug therapy decisions are decisions based on sound evidence.

• Evidence that a drug is safe and effective is obtained from pharmacoepidemiological studies and disseminated via the medical literature.

• Medical literature can be classified as: – primary– secondary– tertiary

Primary medical literature

• Provides new information to the field of medicine and consists of: – descriptive– observational – interventional studies.

• All of these study designs are used to provide new information about the use or effect of a particular drug in a specific population.

• These studies are then published in pharmacy and medical journals.

• Hundreds of medical journals are published every week.

Secondary medical literature

• Consists of indexing systems.

• The secondary systems allow practitioners to search through the vast array of medical journals to find information about a particular subject.

• Some databases provide access to complete article(s), and others provide information only on where to locate the article(s).

• Example: The Medline database, (PubMed) • most commonly used • was created in 1966 • indexes more than 1600 medical journals

Tertiary medical literature

• Consists of literature reviews, which can be in the form of: – textbooks– reference books– review articles in medical journals.

• Before a review is written: – a literature search is conducted using the secondary systems to

identify all of the articles published on a particular subject. – The information is then collated and presented in a manner that

is easily used by practitioners.

• Tertiary resources are quick, efficient resources that are used to answer questions about the most common clinical problems.

• Suppose a patient presents to a clinician complaining of tachycardia.

A. The clinician conducts: 1. a complete medical history 2. physical examination of the patient.

B. If the clinician suspects the tachycardia is an adverse drug reaction associated with a particular medication, then he or she attempts to find evidence in the literature that supports the suspicion.

• The best clinical decisions are based on sound medical evidence, rather than hunches or suspicions.

• To obtain medical evidence on a particular topic, clinicians:

1. first searches the tertiary literature (e.g., textbooks, reference books).

2. If no information is found, a literature search using the secondary systems is conducted.

• A literature search reveals where and when information on the topic has been published

• The clinician must then retrieve and review all of the articles. • The studies must be critiqued with regard to design,

methodology, quality of data, and bias.

• A clinical decision based on sound evidence is then made that either supports or negates the theory that the tachycardia is associated with the use of the drug.

Cochrane Database of Systematic Reviews.

• Archie Cochrane, a physician-epidemiologist, realized that conducting exhaustive literature searches and medical literature reviews were daunting and time-consuming tasks requiring many resources.

• Cochrane believed that clinicians should be able to conduct a search on a specific topic and find a well-conducted, systematic review that identifies and summarizes all of the medical literature published on a particular topic.

• He enlisted a group of international collaborators to create and maintain such a database; it is called the Cochrane Database of Systematic Reviews.

• They have included reviews on: – herbal medicine – Homeopathy: alternative medicine, treats patients with heavily diluted

preparations

– acupuncture – massage

• Cochrane collaborators perform exhaustive searches for published and unpublished studies in English and other languages.

• Whenever possible, the Cochrane reviews are based on: 1. randomized clinical trials (the gold standard in medical

research.)

2. If randomized clinical trials are not available, then the strongest observational studies—the best designed and conducted studies—are used in the Cochrane reviews.

• After completion, the reviews undergo rigorous peer review.

• Cochrane reviews are updated on a regular basis to include new information.

Adverse Drug Reaction Surveillance

• Adverse drug reaction reporting and monitoring plays an important role in the postmarketing surveillance of drugs.

• Pharmacists play an integral part in adverse drug reaction reporting.

• In fact, historically, pharmacists have the highest rate of adverse drug reaction reporting among health care professionals.

• Typically, pharmacists collect and report adverse drug reactions on a regular basis to pharmacy and therapeutics committees (P&T committees) in their individual institution.

• These reports are most commonly used to monitor the safety of drugs within institutions, but pharmacists are usually also responsible for forwarding serious adverse drug reactions to the Food and Drug Administration (FDA).

• Just as the FDA acts after receiving several serious adverse drug reactions associated with a particular drug, the P&T committees of individual institutions react to serious adverse drug reactions within the institution by creating medication guidelines and restrictions.

Drug Utilization Studies

• The World Health Organization (WHO) defines drug utilization as "the marketing, distribution, prescription, and use of drugs in a society, with special emphasis on the resulting medical, social, and economic consequences.''

• Pharmacists conduct drug utilization studies, or DUEs, as part of their routine activities.

• Like adverse drug reaction monitoring, the Joint Commission for the Accreditation of Health Care Organizations (JCAHO) requires health care institutions to conduct drug utilization studies.

• DUEs are most commonly conducted to monitor prescribing patterns.

• Medications monitored via DUE are chosen according to: – cost – frequency of use – risk of toxicity.

• Drugs newly approved by the FDA that have shown serious adverse effects in phase III trials are typically chosen to be monitored via DUEs.

• Example: • when alteplase (TPA ®) was first approved by the FDA, many

practitioners were concerned about the bleeding side effects that had occurred in phase III trials.

• Consequently, pharmacists chose to conduct DUEs to monitor the use of alteplase.

• Information was collected on both prescribers and patients. • Data collected on patients included:

– demographic information– past medical history– Indication– Dose– duration of therapy– specific documentation of unintended bleeding effects.

• The goal of the DUEs was to monitor the use of alteplase to ensure that the drug was being used as indicated in the proper patients and to measure the extent of bleeding associated with alteplase.

• Subjects exposed to a particular drug are followed for a period to determine the incidence of an adverse reaction.

• These DUEs can easily be expanded to a prospective cohort model.

Pharmacoepidemiological Research as an Extension of Daily Clinical Practice

• Pharmacists in clinical settings monitor the uses and effects of drugs on a daily basis.

• Clinical pharmacists collect information about individual patients; however, pharmacists can also choose to view patients as populations, rather than individuals, for the purpose of epidemiological research.

• If information collected about patients is systematic and routine, then the routine monitoring of individual patients can easily be applied to a cohort study design.

• The data collected can then be analyzed to generate new hypotheses or to identify trends of drug use.

• For example, a pharmacist conducting rounds in a critical care unit will collect information about individual patients with regard to demographics, past medical history, current medical problems, laboratory data, physical findings, and so forth.

• The pharmacist will monitor each individual patient in an effort to optimize pharmaceutical care.

• The data collection may or may not be consistent from patient to patient.

• In this scenario, the information is typically used solely for the purpose of caring for the patient.

• The pharmacist could instead choose to develop data-collection forms to be used on all patients.

• If data collection is systematic and consistent, then the data can be analyzed to determine the effects of drugs within populations of patients, rather than thinking of patients only as individuals.

• New hypotheses can be generated from the data collection and analysis; these hypotheses can then be tested using more sophisticated observational or interventional studies.

Professional Organizations and Journals in Epidemiology

Professional organizations 

  American College of Epidemiology

  American Public Health Association

  American Statistical Association, Section on Epidemiology

  Association for Professionals in Infection Control & Epidemiology

  Canadian Society for Epidemiology and Biostatistics

  European Society of Clinical Pharmacy

  International Society for Pharmacoepidemiology

  Society for Epidemiologic Research

Professional journals 

  American Journal of Epidemiology 

  American Journal of Public Health 

  Annals of Epidemiology 

  Biometrics 

  Drug Safety 

  Emerging Infectious Diseases 

  Epidemiologic Reviews 

  Epidemiology 

  Epidemiology and Infection 

  Journal of Clinical Epidemiology 

  Journal of Epidemiology and Community Health 

  MMWR: Morbidity and Mortality Weekly Report 

  Pharmacoepidemiology and Drug Safety 

  Society for Clinical Trials 

  Viral and Health Statistics 

  Weekly Epidemiological Record 

  World Health Statistics Quarterly 

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