Epidemiology

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					               Worldwide trends in prevalence of
                       asthma symptoms:
               phase III of the International Study
                   of Asthma and Allergy in
                      Childhood (ISAAC)




Colin Robertson, Neil Pearce, Nadia Ait-Khaled, Richard
 Beasley, Javier Mallol, Ulrich Keil, Ed Mitchell and the
              ISAAC Phase III Study Group
                  ISAAC Steering Committee
                    R Anderson
                    (M Burr)
                    U Keil
                    D Strachan              B Björkstén
                    E von Mutius
                    S Weiland
(F Martinez)        H Williams

                                         S Montefort
                                                                            C Lai

                                                       JR Shah


                                                                                    S Foliaki
       J Mallol                                           I Asher (chair)
                                                          R Beasley
                                   N Aït-Khaled           J Crane
                                   G Anabwani             E Mitchell
                                                          N Pearce
                                                          C Robertson
       ISAAC                                                                          1998
              ISAAC Objectives
1. To describe the prevalence and severity of asthma,
   rhinitis and eczema in children living in different
   centres and to make comparisons within and between
   countries.
2. To obtain baseline measure for assessment of future
   trends in the prevalence and severity of these
   diseases.
3. To provide a framework for further aetiological
   research into lifestyle, environmental, genetic and
   medical care factors affecting these diseases.
   ISAAC                                                 Tonga
                                                          1998
                                                         2004
       The three phases of ISAAC
I International survey of the prevalence and severity
  of asthma, rhinitis, and eczema in childhood

II Studies of aetiologic factors, including skin tests for
   atopy, lung function and bronchial reactivity, serum
   IgE levels, physical examination, genetic markers,
   aeroallergens at home, and clinical management

III Repetition of Phase I after at least 5 years to
    determine trends in these diseases

   ISAAC                                                 Tonga
                                                          1998
                                                         2004
               Phase One methods
Design:         Multicentre prevalence studies
                Identical methods (but translated questions)

Study areas:    Largely recruited by personal contacts but
                differing in lifestyle and environment

Population:     13-14 year old school children (core)
                6-7 year olds (strongly recommended)

Sample size:    3,000 children ideally (minimum 1,000)

Study period:   July 1992 - December 1995
   ISAAC                                                     Tonga
                                                              1998
                                                             2004
 Phase I and III “core” instruments
• written questionnaires on the prevalence and severity
  of asthma, rhinitis, and eczema for self-completion in
  13 - 14 yr olds (compulsory)

• video questionnaire on the prevalence and severity of
  asthma for self-completion by 13 - 14 yr olds
  (recommended)

• written questionnaires on the prevalence and severity
  of asthma, rhinitis, and eczema for completion by
  parents of 6 - 7 yr olds (recommended)

  ISAAC                                                Tonga
                                                        1998
                                                       2004
Study Centres and Participants: Phase I
13-14 Year Age Group
Region                      Centre Participants Participation
                              n          n            %
Africa                        7      21,648        91%
Asia-Pacific                 20      83,826        94%
Eastern Mediterranean        10      28,468        93%
Latin America                17      52,549        93%
North America                 5      12,460        79%
Northern and Eastern Europe 20       60,819        93%
Oceania                      10      31,301        93%
Southeast Asia               14      37,171        95%
Western Europe               52     135,559        90%
Global Total:               155     463,801        92%
    ISAAC
                                         gm/08/96: stock_2.ppt
    ISAA C   Wheeze in last 12 mths
Phase One      13-14 y r age grp




  20%
10 to <20%
5 to <10%
<5%

                                  1998
              Phase Three methods
Design:    3A   Repeat prevalence studies after 5+ years
           3B   First prevalence studies in new centres
Population:     13-14 year old school children
                6-7 year olds (strongly recommended)

Sample size:    3,000 children ideally (minimum 1,000)

Study period:   1999 to 2003 (phase 3A)
                1998 (“late phase 1”) to 2003 (phase 3B)


   ISAAC                                                   Tonga
                                                            1998
                                                           2004
         Phase Three methods

        Same:
        • sampling frame
        • age groups
        • sample size
        • method for selecting children
        • questionnaires
        • translations
        • time of year

ISAAC                                     Tonga
                                           1998
                                          2004
Study Centres and Participants: Phase III
13-14 Year Age Group
Region                  Phase I   Phase IIIa              Phase IIIb
                        centres    centres                 centres
Africa                     10       9                        14
Asia-Pacific               35       23                       26
Eastern/Northern           17       11                       17
Europe
Eastern Mediterranean      10        6                            11
Latin America              16       15                            67
North America               5        2                            6
Oceania                    10        5                            8
Western Europe             51       34                            12
Global Total:             155      105                           161
    ISAAC
                                         gm/08/96: stock_2.ppt
 CENTRES REGISTERED FOR ISAAC PHASE THREE




Phase 3A centres
Phase 3B centres
Phase 1 centres not
participating in Phase 3
Overall change in prevalence of
   current wheeze

            Phase I   Phase III   % change
                                  per annum
 13-14 yo   13.2%      13.7%        +0.03

  6-7 yo    11.3%      11.8%        +0.07
Overall change in prevalence of
   asthma ever

            Phase I   Phase III   % change
                                  per annum
 13-14 yo   11.3%      13.5%        +0.35

  6-7 yo     9.5%      11.1%        +0.19
Regional changes – percent change per annum
                            13 – 14 yo 6 – 7 yo
Western Europe                -0.32     +0.24
Oceania                       -0.32     -0.27
Latin America                 +0.14     +0.12
Northern & Eastern Europe     +0.63     -0.01
Africa                        +0.28     +0.10
North America                 +0.24     +0.24
Eastern Mediterranean         -0.26     +1.02
Asia Pacific                  -0.01     -0.27
Indian sub-continent          -0.32     -0.07
English speaking countries


     • annual rate of change:
              -0.60 % for 13-14 yo
              -0.18% for 6-7 yo
         ISAAC    Change in Symptoms of Asthma
   Phase Three        13-14 Year Age Group




>2 SE Increase
1-2 SE Increase
No Change
1-2 SE Decrease
>2 SE Decrease                              2005
                    Country ordered by average prevalence

Country (Prev. %)
United Kingdom (28.5)
 New Zealand (28.0)
 Rep. of Ireland (27.9)
    Costa Rica (25.5)
            Peru (22.8)
             USA (22.6)
           Brazil (21.3)
        Panama (20.3)
      Paraguay (20.2)
      Barbados (19.2)
       Uruguay (18.5)
        Ukraine (16.9)
         Finland (16.1)
      Germany (15.8)
    South Africa (15.8)
            Malta (15.3)
          Kenya (14.8)
          Austria (13.4)
          Japan (13.2)
       Romania (12.8)
            Chile (12.8)
      Argentina (12.4)
          Kuwait (12.3)
        Thailand (12.2)
             Iran (12.2)
         Nigeria (11.8)
        Sweden (11.1)
     Singapore (10.6)
    Hong Kong (10.5)
        Portugal (10.4)
     Philippines (10.3)
         Tunisia (10.2)
         Belgium (10.2)
        Pakistan (10.1)
          Ethiopia ( 9.9)
            Spain ( 9.5)
            Latvia ( 9.4)
        Malaysia ( 9.1)
              Italy ( 9.1)
          Mexico ( 9.1)
           Poland ( 9.0)
        Morocco ( 9.0)
          Estonia ( 8.9)
            Oman ( 8.7)
    South Korea ( 8.3)
        Lithuania ( 7.5)
           Algeria ( 7.3)
             India ( 6.2)
          Taiwan ( 6.2)
            China ( 5.1)
         Georgia ( 4.3)
       Indonesia ( 3.6)
          Albania ( 3.0)

                             -3   -2     -1       0         1   2   3

                                        Mean Change per year
                    Country ordered by average prevalence
Country (Prev. %)
            Peru (30.5)
 New Zealand (27.7)
     Singapore (23.7)
United Kingdom (23.0)
      Barbados (20.9)
    Costa Rica (20.8)
           Oman (20.3)
          Japan (19.4)
     Philippines (19.3)
        Panama (18.7)
 Rep. of Ireland (18.4)
             USA (18.3)
       Uruguay (16.7)
          Kuwait (15.8)
         Tunisia (15.6)
         Nigeria (15.0)
       Morocco (14.7)
           Brazil (14.6)
        Portugal (13.2)
         Taiwan (13.1)
          Kenya (12.9)
            Chile (12.8)
            Malta (12.6)
      Paraguay (12.5)
        Thailand (12.3)
    South Africa (12.1)
           Spain (11.8)
       Malaysia (11.5)
        Sweden (11.1)
    Hong Kong (10.7)
             Italy (10.5)
        Argentina ( 9.6)
          Belgium ( 8.3)
        Germany ( 7.5)
         Pakistan ( 7.4)
       Indonesia ( 7.0)
        Romania ( 6.3)
           Austria ( 6.2)
          Finland ( 6.1)
           Algeria ( 5.9)
         Ukraine ( 5.8)
          Mexico ( 5.6)
            Latvia ( 5.6)
            China ( 5.4)
             India ( 5.2)
           Poland ( 4.1)
          Estonia ( 4.0)
    South Korea ( 3.9)
         Georgia ( 3.5)
               Iran ( 3.1)
        Lithuania ( 2.7)
          Ethiopia ( 2.6)
          Albania ( 2.6)

                             -2      -1            0             1   2

                                          Mean Change per year
Key Findings From ISAAC Phase III
• Little change in overall prevalence
• International differences in asthma symptom
    prevalence have reduced
•   Decreases in English-speaking countries
•   Increases in some (but not all) regions where
    prevalence was previously low
•   Increases in diagnosed asthma in most regions
•   Particular increases in Africa, Latin America and parts
    of Asia – asthma is no longer an “English speaking”
    disease
•   Need for standardised objective measure of asthma
    for international epidemiologic studies
I nternational
S tudy of
A sthma and
A llergies in
C hildhood

				
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posted:8/9/2011
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