Epidemic AsthmaRuth A. Etzel

Problem-Based Exercises for Environmental EpidemiologyWorld Health, WHO/EHG/98.2, 1998, 45-53.

16 November 2015

Barcelona Asthma Epidemic

Question 1: What is asthma?

130 hospital visits for difficulty breathing on 21 Jan 1986

Question 3: Review of the hospital records reveals that the four hospitals treated 288 persons with asthma during the month of January 1986. Now can you determine if this is an epidemic?

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

288 persons with asthma treated in Jan 1986

Question 4: Develop a preliminary case definition

1985 Average 159 acute asthma ER visits per monthMax 199

Question 5: Do you now have sufficient information to determine if there is an epidemic of asthma?

January 1986 Total 288 acute asthma ER visits

Average 9.3 per dayMax 96 on Jan 21st

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 310

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Question 6: Draw a bar chart of the number of acute asthma emergency room visits by day in January 1986

Question 7: What other information would be useful to characterize the epidemic?

Age Sex Time Place Age Sex Time Place Age Sex Time Place18 F 0:30 7 41 F 11:50 4 47 F 14:30 118 M 0:50 3 40 F 12:00 3 28 F 14:30 219 F 2:20 3 40 M 12:05 1 57 M 14:40 219 M 5:10 3 27 F 12:05 2 28 M 14:50 220 M 6:15 8 41 M 12:08 10 57 F 15:05 220 F 9:25 8 89 M 12:10 2 69 M 15:10 240 M 10:00 3 30 M 12:15 2 70 M 15:15 240 M 10:05 1 37 M 12:17 1 49 F 15:20 241 M 10:08 10 29 F 12:20 2 40 F 15:25 237 M 10:17 1 39 M 12:25 1 40 F 15:25 239 F 10:25 1 19 F 12:25 1 47 M 15:30 139 M 10:25 1 30 F 12:25 2 48 F 15:30 238 M 10:35 1 67 F 12:30 1 47 M 15:40 238 F 10:45 1 18 F 12:30 2 58 M 15:50 241 F 10:55 4 38 M 12:35 1 48 F 16:30 160 M 11:00 3 27 M 12:40 2 67 M 16:40 240 M 11:05 1 68 M 12:45 1 48 M 16:50 217 F 11:05 2 28 M 12:50 2 47 M 16:50 241 M 11:08 10 41 M 12:55 4 49 M 17:10 129 M 11:10 2 27 F 13:05 2 40 M 17:15 150 M 11:15 2 29 M 13:10 2 19 F 17:20 137 M 11:17 1 30 M 13:15 2 40 F 17:25 129 F 11:20 2 29 F 13:20 2 49 F 18:20 339 M 11:25 1 30 F 13:25 2 48 F 18:30 1059 M 11:25 1 28 F 13:30 2 38 M 18:50 130 F 11:25 2 27 M 13:40 2 49 M 19:10 337 F 11:30 1 28 M 13:50 2 40 M 19:15 678 F 11:30 2 27 F 14:05 2 40 F 19:25 738 M 11:35 1 29 M 14:10 2 59 M 21:20 327 M 11:40 2 50 M 14:15 2 59 M 22:10 638 F 11:45 1 29 F 14:20 2 10 M 23:15 728 M 11:50 2 30 F 14:25 2 15 F 23:25 6

Age, sex, time and place of onset of illness, for each person who came to the emergency room with acute asthma on 21 January 1986

28

44

9

3

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4

Question 8: On the attached city map, show the geographic distribution of the place of onset of illness (Table 3) for the 96 persons who came to the emergency rooms with acute asthma on January 21st. What does this distribution suggest?

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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

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Hour

Question 8: Draw a bar-chart of the cases by hour of occurrence (Table 3), What hypotheses are suggested?

Question 10: What conclusion can you draw from this information?

Question 11: How would you use this information to further explore this problem?

Counts of days on which each product was loaded or unloaded from barges or boats

Days Product is Handled Days Product is NOT Handled (Loaded or Unloaded) (Loaded or Unloaded) Asthma Epidemic Days Asthma Epidemic DaysPRODUCT NO YES NO YES

Coal 196 4 521 9Fuel Oil 150 3 567 10Gasoline 180 2 537 22Cotton 399 7 318 6Coffee 300 5 417 8Corn 135 1 582 12Soybeans 249 13 468 0Butane 140 1 577 12

Question 12. Using the information in Table 4, complete the tables on the following pages and calculate the risk ratios. Optional: calculate the confidence interval (C.I.) for each table.

Yes NoEpidemic Yes 4 9 13Asthma No 196 521 717

200 530 730

Coal

OR (95% CI)=1.18 (0.26, 4.29)

Yes No Yes NoEpidemic Yes 4 9 13 Epidemic Yes 5 8 13Asthma No 196 521 717 Asthma No 300 417 717

200 530 730 305 425 730

Yes No Yes NoEpidemic Yes 3 10 13 Epidemic Yes 1 12 13Asthma No 150 567 717 Asthma No 135 582 717

153 577 730 136 594 730

Yes No Yes NoEpidemic Yes 2 11 13 Epidemic Yes 13 0 13Asthma No 180 537 717 Asthma No 249 468 717

182 548 730 262 468 730

Yes No Yes NoEpidemic Yes 7 6 13 Epidemic Yes 1 12 13Asthma No 399 318 717 Asthma No 140 577 717

406 324 730 141 589 730

Coal Coffee

OR (95% CI)=0.34(0.01, 2.36)

Cotton

Gasoline Soybeans

Butane

CornFuel Oil

OR (95% CI)=0.36 (0.01, 2.47)

OR (95% CI)=UndefinedOR (95% CI)=0.54 (0.06, 2.52)

OR (95% CI)=0.93 (0.26, 3.38)

OR (95% CI)=0.87 (0.22, 3.05)OR (95% CI)=1.18 (0.26, 4.29)

OR (95% CI)=1.13 (0.20, 4.48)

Question 13: How do you interpret the risk ratios and confidence intervals you have calculated?

Question 14: Now substitute a 1.0 for the 0 in cell B (soybeans) and recalculate.

Yes No Yes NoEpidemic Yes 13 0 13 Yes 13 1 14Asthma No 249 468 717 No 249 468 717

262 468 730 262 469 731

SoybeansSoybeans