Drug Hypersensitivity Prevalence in the Adult Population Group 13 Medical Faculty of University of Porto Medical Faculty of University of Porto Introduction to Medicine 2005/06

2 Summary  Introduction  Aim  Methods  Expected Results  Limitations

3 Introduction  Drug hypersensitivity reactions are the side effects of drugs taken at a dose that is tolerated by normal subjects 1  Drug hypersensitivity reactions are thought to represent one-third of adverse drug reactions 1 1- Gomes et al. Self-reported drug allergy in a general adult Portuguese population.

4 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 death 2,3  Allergic reactions are one of the examples of unpredictable reactions Gruchalla, Rebecca. Drug metabolism, danger signals, and drug-induced hypersensitivity. 3 –Gruchalla, Rebecca. Understanding drug allergies.

5 Introduction  Drug hypersensitivity is a common and complicated problem in clinical practice 4  It shows in various forms of autoimmune diseases 4  Diagnosis of drug hypersensibility is difficult 4  Drug-allergic reactions are underdiagnosed 4 4– Demoly, P, Kropf, R:, Bircher A. et Pichler W.J. Drug hypersensitivity: questionnaire.

6 Introduction  5% of all hospital admissions are due to adverse drug reactions 2  Fatal adverse drug reactions are between the 4 th and 6 th leading cause of death of hospitalized patients in the USA 3  3-7% of the population experience an adverse drug reaction 1 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.

7 Introduction  Drugs most commonly observed as the cause of these reactions 3 : –ampicillin –amoxicillin –trimethoprim-sulfamethoxazole –penicillin 3 - Gruchalla, Rebecca. Understanding drug allergies.

8 Introduction  Common diseases and symptoms provoked by drug hypersensitivity 4 : –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

9 Aim The aim of this study is to determine the prevalence of drug hypersensitivity in the adult population of Porto region

10 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.

11 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

12 Fluxogram

13 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

14 Random Digital Dialling 5  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.

15 Data collection methods  Telephone interview  Questionnaire Questionnaire

16 Main variables description  Age  Sex  Reaction type  Symptoms  Suspected drug  Allergies in family medical history

17 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

18 Gantt chart  Microsoft Project Microsoft Project

19 Expected Results  We expect that our study reveals about 3- 7% of adverse drug reactions in our population as reported 1 1- Gomes et al. Self-reported drug allergy in a general adult Portuguese population.

20 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

21 References 1 - Gomes et al. Self-reported drug allergy in a general adult Portuguese population. Clin Exp Allergy 2004; 34: Gruchalla, Rebecca. Drug metabolism, danger signals, and drug-induced hypersensitivity. J Allergy Clin Immunol October Gruchalla, Rebecca. Understanding drug allergies. J Allergy Clin Immunol June Demoly, P, Kropf, R:, Bircher A. et Pichler W.J. Drug hypersensitivity: questionnaire. Allergy 1999, 54, Groves, R et al. Telephone Survey Methodology. John Wiley & Sons Inc 2001

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