epidemic asthma

7/17/2019 Epidemic Asthma

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Case 6. Epidemic asthma

Learning objectives:

1. Developing a case definition

2. Interpreting descriptive data

3. Constructing histograms

4. Plotting the distribution of cases

5. Constructing 2x2 tables

. Calculating ris! ratios "odds ratios#

$. Identif%ing intervention strategies for prevention

PART 1 - ITR!"#CTI!

&arcelona is a cit% of 1.$ million situated on the 'editerranean (ea.

During the last )ee! of *anuar% 1+,- several ph%sicians contacted public health authorities to

report an increase in the number of persons )ho had come to the emergenc% rooms of the fourlarge urban hospitals see!ing medical care for acute severe asthma. (pecificall%- on uesda% 21

*anuar% 1+, a total of over 13/ people had sought care at these hospitals for difficult% in

breathing. 'ost of these people )ere thought to be suffering asthma attac!s. he attac!s struc!ver% suddenl% and caused such severe problems that 1/0 of the patients reuired ventilator%

support and 20 died.

Question 1: What is asthma?

Question 2: Is this an epidemic of asthma? What further information do you need?

Question 3: Review of the hospital records reveals that the four hospitals treated 288

persons with asthma during the month of anuary 1!8"# $ow can you determine if this is

an epidemic?



Question %: &evelop a preliminary case definition#

Question ': &o you now have sufficient information to determine if there is an epidemic of

asthma ()a*le 1+?

$um*er

15

12,

13,

124

Question ": ,rint the attached graph paper and draw a *ar-chart of the data ta*ulated

a*ove in )a*le 2# What additional information does the *ar-chart provide?

.raph ,aper

http://www.who.int/peh/Occupational_health/OCHweb/OSHpages/OSHDocuments/EpidemiologyTraining/training_problembased/case6_table1.htm

http://www.who.int/peh/Occupational_health/OCHweb/OSHpages/OSHDocuments/EpidemiologyTraining/training_problembased/graph_paper.htm








&ay $um*er

14

15 $

1

1$ $

1, 4

1+ +



Question /: What other information would *e useful to characterise the epidemic?

Question 8: 0n the attached city map using dots show the geographic distri*ution of the

place of onset of illness ()a*le 3+ for the !" persons who came to the emergency rooms withacute asthma on 21 anuary# What does this distri*ution suggest?

http://www.who.int/peh/Occupational_health/OCHweb/OSHpages/OSHDocuments/EpidemiologyTraining/training_problembased/case6_citymap.htm


http://www.who.int/peh/Occupational_health/OCHweb/OSHpages/OSHDocuments/EpidemiologyTraining/training_problembased/case6_citymap.htm




)a*le 3.ge se time and place of onset of illness for each of the persons who came

to the emergency room with acute asthma on 2145141!8"#

g

e

6e

)ime of

onset

,lace of

onset

(Region+

ge 6e )ime of

onset

,lace of onset (Region+

41 1/55 4 4/ ' 1/// 3

2, ' 125/ 2 41 ' 1//, 1/

2$ ' 134/ 2 2, 133/ 2

4/ 12// 3 4, 13/ 1

3/ 1325 2 2+ ' 131/ 2

1+ /22/ 3 3/ ' 1315 2

1$ 11/5 2 2$ 14/5 2

4/ ' 1$15 1 5$ ' 144/ 2

2, ' 135/ 2 2, ' 145/ 2

4+ ' 1$1/ 1 3/ 1125 2

4$ 143/ 1 2+ 142/ 2

2+ ' 111/ 2 2+ ' 141/ 2

2, 143/ 2 5/ ' 1415 2

3, ' 1135 1 3/ 1425 2

4+ 1,2/ 3 41 ' 1255 4

5+ ' 221/ 4/ 1525 2

3+ ' 1125 1 5$ 15/5 2

4/ ' 11/5 1 4$ ' 154/ 2

5+ ' 212/ 3 5, ' 155/ 2

41 ' 11/, 1/ 41 115/ 4

1/ ' 2315 $ 4, 153/ 2

2$ 12/5 2 + ' 151/ 2

2$ ' 124/ 2 4/ 1525 2

2/ /+25 , 2$ 13/5 2

2$ ' 114/ 2 4$ ' 15/ 2

1, 123/ 2 ,+ ' 121/ 2

3/ ' 1215 2 4+ 152/ 2

4, ' 1.5/ 2 2+ 122/ 2

3/ 1225 2 1+ 1$2/ 1



2+ 132/ 2 $ 123/ 1

3$ ' 121$ 1 4/ 1$25 1

3, ' 1235 1 2+ 112/ 2

3+ ' 1225 1 $, 113/ 2

4/ ' 12/5 1 , ' 1245 13$ 113/ 1 1+ 1225 1

41 ' 12/, 1/ 3, ' 1,5/ 1

4/ ' 1+15 4, 1,3/ 1/

3$ ' 1/1$ 1 3$ ' 111$ 1

3, ' 1/35 1 4+ ' 1+1/ 3

3, 1/45 1 3, 1145 1

3+ 1/25 1 4/ 1+25 $

3+ ' 1/25 1 5+ ' 1125 1

4/ ' 1//5 1 / ' 11// 315 2325 1+ ' /51/ 3

1, ' //5/ 3 2/ ' /15 ,

$/ ' 1515 2 4$ ' 153/ 1

1, //3/ $ $ ' 14/ 2

5/ ' 1115 2 2, ' 115/ 2

Question !: ,rint the attached graph paper and draw a *ar-chart of the cases *y hour of

occurrence ()a*le 3+# What hypotheses are suggested?

.raph ,aper







PART $

In %our discussions )ith emergenc% room personnel- %ou learn that this is not the first time that

the hospitals have been over)helmed )ith patients suffering from acute asthma attac!s. ou are

told that asthma epidemic da%s have occurred on 12 other occasions during the last 2 %ears.

6oting the clustering of asthma emergenc% room visits in space and time- %ou reuest data on air pollution in the cit% during the past t)o %ears. or uesda% 21 *anuar%- air pollution levels )ere

belo) normal for the cit%. he 247h average level of sulphur dioxide )as 54 8g9m3 and that of

blac! smo!e )as +, 8g9m3. he highest hourl% mean for nitrogen dioxide )as 1/ ppb. )ent%7four hour pollen and spore counts )ere also belo) average for that time of %ear. 'eteorologic

data sho)ed high atmospheric pressure and stagnanc% of the air )ith a ver% lo) )ind speed.

Question 15: What conclusions can you draw from this information?

(ince man% persons reported that the% )ere affected in the centre of the cit%- near the )aterfront-

%ou decide to find out more information about the activities there. ou learn that the follo)ing ,

products )ere either loaded or unloaded from barges and boo!s in the harbour during the lastt)o %ears.

Coal

Cotton

:asoline(o%beans

uel oil

CoffeeCorn

&utane

Question 11: 7ow would you use this information to further eplore this pro*lem?



ou as! for dates on )hich each of these products )ere loaded or unloaded from barges or boats.

his information is sho)n in able 4.

able 4

&ays ,roduct is 7andled

";oaded or <nloaded#

&ays ,roduct is $0) 7andled

";oaded or <nloaded#

=sthma >pidemic Da%s =sthma >pidemic Da%s

Product

6? >( 6? >(

Coal

1+ 4 521 +

uel ?il

15/ 3 5$ 1/

:asoline

1,/ 2 53$ 11

Cotton

3++ $ 31,

Coffee3// 5 41$ ,

Corn

135 1 5,2 12

(o%beans

24+ 13 4, /

&utane

14/ 1 5$$ 12





Question 12: sing the information in )a*le % print and complete the following ta*les and

calculate a ris9 ratio and confidence interval (#I+ for each ta*le (use the formulas

presented in class discussion# lso the computer software ;,II$<0 will *e demonstrated

to calculate confidence intervals+#

)wo *y )wo )a*les =ased on )a*le %#

<nloading Coal

<nloading Corn

es 6o es 6o

>pidemic

=sthma es

>pidemic

=sthma es

Da% 6o

Da% 6o

<nloading uel ?il <nloading (o%beans

"1#

es 6o es 6o

>pidemic=sthma es

>pidemic=sthma es

Da%

6o

Da%

6o

<nloading :asoline

<nloading (o%beans

"2#

es 6o es 6o

>pidemic

=sthma es

>pidemic

=sthma es


http://www.who.int/peh/Occupational_health/OCHweb/OSHpages/OSHDocuments/EpidemiologyTraining/training_problembased/case6_tablecoml.htm


http://www.who.int/peh/Occupational_health/OCHweb/OSHpages/OSHDocuments/EpidemiologyTraining/training_problembased/case6_tablecoml.htm



Da%

6o

Da%

6o

<nloading Cotton

<nloading &utane

es 6o es 6o

>pidemic

=sthma es

>pidemic

=sthma es

Da%

6o

Da%

6o

<nloading Coffee

es 6o

>pidemic

=sthma es

Da%

6o

Question 13: 7ow do you interpret the ris9 ratios and confidence intervals you have

calculated?

Question 1%: $ow su*stitute a 1#5 for the 5 in cell = (soy*eans+ and re-calculate#

Question 1': 7ow would you proceed from here?

PART %



Question 1": &evelop a strategy for prevention of asthma epidemics in the city#

Question 1/: 7ow would you assess the costs of this prevention strategy compared to the

costs of the emergency visits for asthma attac9s?

Based on a report by Anto, J.M. et al. Community outbreaks of asthma associated with inhalation of soybean dust.The New n!land Journal of Medicine, "#$#, %&'(")*+ "'#)""'& -or further study of methodolo!y for epidemiolo!ic studies of asthma, the followin! reiew article is recommended+

Anto, J.M. / 0unyer, J. pidemiolo!ic studies of asthma epidemics in Barcelona. Chest, Noember, "##'

(0upplement*+ "$1s"$#s.