Drug Hypersensitivity Prevalence in the Adult Population Group 13 Faculty of Medicine of the University of Porto Faculty of Medicine of the University of Porto Department of Biostatistics and Medical Informatics 2005/06

2 Table of contents  Introduction –Aim  Participants and Methods  Results  Discussion and Limitations  Website project

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. Clin Exp Allergy 2004; 34:

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 R. Drug metabolism, danger signals, and drug-induced hypersensitivity. J Allergy Clin Immunol October –Gruchalla R. Understanding drug allergies. J Allergy Clin Immunol June 2000

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. Allergy 1999, 54,

6 Introduction  3-7% of the population experience an adverse drug reaction 1  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 Gomes et al. Self-reported drug allergy in a general adult Portuguese population. Clin Exp Allergy 2004; 34: Gruchalla R. Drug metabolism, danger signals, and drug-induced hypersensitivity. J Allergy Clin Immunol October Gruchalla R. Understanding drug allergies. J Allergy Clin Immunol June 2000

7 Introduction  Drugs most commonly observed as the cause of these reactions 3 : –ampicillin –amoxicillin –trimethoprim-sulfamethoxazole –penicillin 3 - Gruchalla R. Understanding drug allergies. J Allergy Clin Immunol June 2000

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. Allergy 1999, 54, © Dermatology database of Institute for Biomedical Informatics, Faculty of Medicine, Ljubljana, Slovenia

9 Aim To determine the lifetime prevalence of drug hypersensitivity in the adult population

10 Secondary Aims  Identify the drugs that are more frequently associated to hypersensitive reactions, (classifying them using the same system of INFARMED data base);  Describe the different types of allergic expression;  Relate the allergic reactions already described with the presence of some diseases;

11 Study participants  Target population - all adult people (above 18 years old) living in Porto region  Available population - all adult people living in Porto region with telephone in their household  Unit of Analysis – single person  Inclusion Criteria – be an adult, have phone in their household, live in Porto and have capacities to answer the questionnaire properly  Exclusion Criteria – see flowchart

12 Flowchart

13 Study design  Observational, cross-sectional and descriptive study, executed via phone interviews.  Data collection method – Phone interviews, filling up a questionnaire previously designed  Sample selection method – two stages random digit dialling  Frequency measurement – lifetime prevalence

14 Random Digit Dialling 5  Two Stages RDD Sampling Methods  Will be used relative to the telephone numbers of Porto region.  Software will randomly select digits of the type 22xxxxx and generate prefix numbers  Software will randomly select two digits and generate suffix numbers 5 - Groves, R et al. Telephone Survey Methodology. John Wiley & Sons Inc 2001

15 Random Digit Dialling

16 Data collection methods  Telephone interview  Questionnaire Questionnaire

17 Main variables description  Presence of drug allergies in a life time period  Reaction type (skin, respiratory, digestive, others)  Suspected drug  Presence of allergic diseases  Other diseases  Age  Sex

18 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

19 Results

20 Results

21 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.

22 Results

23 Results

24 Results

25 Results

26 Results

27 Results

28 Main limitations  Telephone interviews may not be accurate enough to determine whether a reaction is really of hypersensitivity or not  People living in Porto, without a telephone at home are excluded  Interviews were done in a restricted period of time  Very low response rate

29 Discussion - difficulties  Questionnaire introduction was not very appropriate: –excessive extension; –complexity of phrasal structure and lexicon;  Low cooperation of the inquired population: –difficulties to understand what was being said (advanced age); –lack of time (active class);  Slanting of the inquired population due to the impossibility of making phone calls during all day: –majority of the population inquired was of advanced age; –phone calls made only in the morning and afternoon; –active population excluded;

30 Discussion - difficulties  Difficulties to contact the resident: –the person who answered the phone didn’t live there and was incapable to give us an hour for future contacting; –Most of the times, the person who was next to celebrate birthday was impossible to reach;  Lots of unfruitful phone calls: –most of the numbers dialed were not available; –great part of the available phone numbers were not residences; –this lead to a waste of precious time;  When the first combination of prefix and suffix was a residence, the majority of next ones weren’t either: –we had to make dozens of phone calls with the same prefix to obtain five residences.

31 Gantt chart  Microsoft Project Microsoft Project

32 Website project Home Abstract Abstract in portuguese Introduction Participants and Methods Results Discussion Conclusions References Authors and contacts Full article (pdf) Work package Gantt chart Presentations SPSS sintax SPSS tables Related websites

33 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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