The Burden and Distribution of Gastrointestinal Illness in the Community

1. The Burden and Distribution of Gastrointestinal Illness in the Community Shannon Majowicz, M.Sc. University of Guelph / Health Canada September 21, 2004

2. Background: What is the “picture” of gastrointestinal illness in the population? • Surveillance data and administrative data have inherent biases • Estimates from community-based studies done in other countries may not be applicable to the Canadian population

3. Primary Objectives: • Magnitude and Distribution • Burden and Costs • Under-reporting Secondary Objectives: • Case definitions

4. Study Design: • Population = the city of Hamilton (pop. 490,290) • Random telephone survey of all residents • n=3496, collected over 12 months • Liberal case definition for data collection: any vomiting or diarrhea in the last 28 days • Initial questionnaire compiled using existing questionnaires: FoodNet, other studies Canadian National Population Health Survey 1996 Census

5. Data Collected: Symptoms Vomiting, diarrhea, cramps, fever, etc. Medical History Pre-existing conditions / illnesses, or prior treatments Severity / Burden and Health Care Use School / work missed, time lost, visiting or phoning a health care practitioner, hospitalization, stool samples Medication Use Pre-illness medications, and those used for the illness Demographics “Opinion”

6. Results: • Response rate = 37% • 1.3 episodes per person-year • Monthly prevalence = 10% • Prevalence higher in: • Women • Those under 10 and 20-24 years of age • Interestingly, the person with the longest duration (40 days) was the only culture-confirmed case

7. Results:

8. Results: Some of the more interesting responses as to why people thought they became ill… “He’s in college and he drinks every weekend” “Taking stool softeners, too many drugs that build up and then you explode” “Knew it was her nerves because she was getting married the next day”

9. Results: • Cost per case of GI = $1,089 CAD • Cost per capita-at-risk = $115 CAD • Per 100,000 population, annually: • 126,320 cases • 37,000 physician visits • 4,400 ER visits • 30 hospitalizations • 4,200 cases submitted 5,000 stools • 23,000 cases and 6,000 caregivers missed 93,000 days of paid employment

10. Reporting chain step Mean Reported to province 1 Reported to local health unit 1.24 Tests positive 1.56 Stool tested 13.83 Stool submitted 14.57 Stool requested 18.73 Visits physician 72.80 Community cases 312.92 Results:Cumulative number of cases of infectious gastrointestinal illness captured at each step in the reporting chain and occurring in the community, for each case of enteric illness reported to the province, in Ontario

11. Conclusions: • Observed epidemiology of GI in this Canadian-based population is similar to other published studies • The burden and cost of GI in this population is significant enough to justify prevention efforts (1.3 episodes per person-year; $115 per capita) • Notifiable disease data significantly under-report the true burden of GI in the population and should be used/interpreted accordingly

12. Contact Info: Shannon Majowicz Tel.: 519-826-2201 Email: shannon_majowicz@hc-sc.gc.ca See also: http://www.hc-sc.gc.ca/pphb-dgspsp/nsagi-enmga/