Drug Hypersensitivity Prevalence in the Adult

Population

Group 13

Medical Faculty of University of PortoMedical Faculty of University of Porto

Introduction to MedicineIntroduction to Medicine2005/062005/06

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Summary

Introduction Aim Methods Expected Results Limitations

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Introduction

Drug hypersensitivity reactions are the side effects of drugs taken at a dose that is tolerated by normal subjects1

Drug hypersensitivity reactions are thought to represent one-third of adverse drug reactions1

1- Gomes et al. Self-reported drug allergy in a general adult Portuguese population.

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Introduction

80% of adverse drug reactions are predictable (type A reactions)2

Type B reactions are not predictable, are dose independent, are not related with the pharmacologic actions of the drug and are extremely important because they are often serious and can cause death2,3

Allergic reactions are one of the examples of unpredictable reactions3

2 - Gruchalla, Rebecca. Drug metabolism, danger signals, and drug-induced hypersensitivity.

3 –Gruchalla, Rebecca. Understanding drug allergies.

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Introduction

Drug hypersensitivity is a common and complicated problem in clinical practice4

It shows in various forms of autoimmune diseases4

Diagnosis of drug hypersensibility is difficult4

Drug-allergic reactions are underdiagnosed4

4– Demoly, P, Kropf, R:, Bircher A. et Pichler W.J. Drug hypersensitivity: questionnaire.

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Introduction

5% of all hospital admissions are due to adverse drug reactions2

Fatal adverse drug reactions are between the 4th and 6th leading cause of death of hospitalized patients in the USA3

3-7% of the population experience an adverse drug reaction1

1- Gomes et al. Self-reported drug allergy in a general adult Portuguese population.

2 - Gruchalla, Rebecca. Drug metabolism, danger signals, and drug-induced hypersensitivity.

3 - Gruchalla, Rebecca. Understanding drug allergies.

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Introduction

Drugs most commonly observed as the cause of these reactions3: – ampicillin– amoxicillin– trimethoprim-sulfamethoxazole – penicillin

3 - Gruchalla, Rebecca. Understanding drug allergies.

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Introduction Common diseases and symptoms provoked

by drug hypersensitivity4:– Exanthema (most common)– Urticaria– Anaphylaxis– Blood cell dyscrasia– Fever– Intersticial lung disease– Hepatitis– Nephritis

4– Demoly, P, Kropf, R:, Bircher A. et Pichler W.J. Drug hypersensitivity: questionnaire.

© Dermatology database of Institute for Biomedical Informatics, Faculty of Medicine, Ljubljana, Slovenia

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Aim

The aim of this study is to determine the prevalence of drug hypersensitivity in the

adult population of Porto region

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Secondary Aims Identify the drugs that are more frequently

associated to hypersensitive reactions, classifying them using the INFARMED data base;

Describe the different types of allergic expression; Relate the allergic reactions already described with

the presence of some diseases; Study the possible existence of an association

between drug hypersensitivity in the interviewed subject and the number of relatives with the same pathology.

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Study participants Target population - all adult people (above 18

years old) living in Porto region Available population - all adult people (above 18

years old) living in Porto region with telephone in their household

Unit of Analysis – single person Inclusion Criteria – be an adult (above 18 years

old), have phone in their household, live in Porto and have capacities to answer the questionnaire properly

Exclusion Criteria – see fluxogram

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Fluxogram

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Study design

Observational, cross-sectional and descriptive study, realized by phone interviews

Data collection method – Phone interview, filling up a questionnaire previously designed

Sample selection method – random digit dialling

Frequency measurement - prevalence

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Random Digital Dialling5

Will be aplicated to the telephone numbers of Porto region

Software will randomly select digits of the type 22xxxxxxx, where x is a digit between 0 and 9

5- Groves, R et al. Telephone Survey Methodology.

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Data collection methods

Telephone interview Questionnaire

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Main variables description

Age Sex Reaction type Symptoms Suspected drug Allergies in family medical history

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Statistical Analysis

We will use SPSS® 13.0 software Descriptive statistics and hypothesis t tests

shall be used to analyse data We will use odds ratio as an association

measure

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Gantt chart

Microsoft Project

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Expected Results

We expect that our study reveals about 3-7% of adverse drug reactions in our population as reported1

1- Gomes et al. Self-reported drug allergy in a general adult Portuguese population.

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Main limitations

Telephone interviews are not accurate to determine whether a reaction is really of hypersensitivity or not

People living in Porto, without telephone at home are excluded

Interviews will be done in a restricted period of time

Low response rate

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References1 - Gomes et al. Self-reported drug allergy in a general adult

Portuguese population. Clin Exp Allergy 2004; 34:1597-1601

2 - Gruchalla, Rebecca. Drug metabolism, danger signals, and drug-induced hypersensitivity. J Allergy Clin Immunol October 2001

3 - Gruchalla, Rebecca. Understanding drug allergies. J Allergy Clin Immunol June 2000

4 - Demoly, P, Kropf, R:, Bircher A. et Pichler W.J. Drug hypersensitivity: questionnaire. Allergy 1999, 54, 999-1003

5 - Groves, R et al. Telephone Survey Methodology. John Wiley & Sons Inc 2001

The End