Module I Managing Case Information: Creating a Line Listing

Learning objectives Become familiar with a “line listing” as a valuable epidemiologic tool Describe the components needed to create a line listing Identify the usefulness of frequency distributions in a line listing Goal To enable users to effectively manage case information

1.Verify the diagnosis and confirm the outbreak 2.Define a case and conduct case finding 3.Tabulate and orient data: time, place, person 4.Take immediate control measures 5.Formulate and test hypothesis 6.Plan and execute additional studies 7.Implement and evaluate control measures 8.Communicate findings Basic Steps to an Outbreak Investigation

Fictional Scenario The school nurse at the local high school calls the LHD to report that 10 students with fever and vomiting were dismissed after lunch. As the afternoon goes on, more students present with the same symptoms and are sent home.

What is a Line Listing? A line listing provides organized information about the cases in an outbreak Can be quickly reviewed and updated Allows for assessment and characterization of an outbreak Provides information for an epidemic curve

Finding Cases Active Call hospitals, health care providers, daycare centers, schools Interviews, surveys In this scenario: call the school nurse, health care providers, parents

Finding Cases Passive Receive lab reports, phone calls In this scenario: receipt of lab reports, phone calls from the school nurse or parents whose child was ill.

Case Definition A set of criteria that must be met in order to identify a person as a case. Criteria include: –clinical (symptoms, laboratory tests) –person, place, and time In this scenario: -Fever and vomiting -High school students who have eaten in the cafeteria

Example of a Line Listing Signs/SymptomsLabsDemographics Case # Date of Symptom Onset DiarrheaVomitingFever >101 Positive stool culture AgeGender 11/2/04yes ? 19M 21/5/04noyesno 17M 31/2/04noyesnoyes23F 41/7/04yes 18? 51/1/04?yes 18F

Creating a Line Listing Create a table –each row represents a case (person) –each column represents a variable of interest Add new cases as identified Update case information throughout the investigation

Variables to Always Include Components of the case definition (clinical information) Case name or identifying number Date of symptom onset Specimen collection date

Optional Variables Age Gender Race Occupation Risk factors

Information from a Line Listing Frequency distributions of demographics May provide information about exposure and/or risk of disease Frequency distributions of potential sources of exposure May provide information about source or route of transmission

Interpreting a Line Listing: Demographics Signs/SymptomsLabsDemographics Case # Date of Symptom DiarrheaVomitingFever >101 Positive stool culture AgeGender 11/2/2004yes ? 19M 21/5/2004noyesno 17M 31/2/2004noyesnoyes23F 41/7/2004yes 18? 51/1/2004?yes 18F 6 1/3/2004 yesnoyes 20F 7 1/3/2004 noyes?no19F 8 1/7/2004 yes 15F 9 1/2/2007 yesnoyes 17F 10 1/1/2004 yes 17F

Interpreting a Line Listing: Frequency Distribution Case # Date of Symptom OnsetFeverDiarrheaGenderLab Results PFGE analysis? PFGE match? 19/18/2004yes F L. monocytogenesyes 29/18/2004yes F L. monocytogenesyes 39/17/2004yes F L. monocytogenesyes 49/18/2004yes M L. monocytogenesyes 59/19/2004yes F L. monocytogenesyes

Conclusions Finding cases is necessary to characterize the outbreak as accurately as possible A line listing enables the investigator to quickly summarize, visualize and analyze the key components of the outbreak

Activity

Outbreak Scenario Activity Review scenario Define the headers or variables that would be included in the line listing Do not fill in the rows with cases

Outbreak Scenario In December 2003, an outbreak of E. coli 0157 occurred among tenth-grade students from City High School. The students traveled between December 2-7. Although the students were broken down into smaller groups, the itineraries were similar for each group. Teachers and other adult chaperones accompanied the students, but no adult reported illness. In addition, no illness was reported among students who did not go on the field trip, and no cases of E. coli 0157 were reported in the community that week. Symptoms of gastroenteritis include severe abdominal pain and/or diarrhea and the average incubation period is 3-4 days.

Possible Line Listing Headers

Example of Final Line Listing Patient #AgeSexOnset Date Severe Abdominal Pain No. Times Diarrhea Stool Testing 117MDec 8Y3Not Done 216FDec 6N1Negative 316MDec 10Y2E. coli FDec 8Y3Not Done 516FDec 5Y8E. coli MDec 7Y3Negative 717MDec 7Y3E. Coli FDec 9Y3E. Coli FDec 7N1Negative 1017FDec 6Y3Not Done

Questions?

References 1.Last, JM. A Dictionary of Epidemiology. Oxford Univ Press, Nelson, KE and Williams CM. Infectious Disease Epidemiology Theory, and Practice. Jones and Bartlett, 2nd edition, “I is for Investigation, Session I: Recognizing an Outbreak.” UNC Chapel Hill School of Public Health North Carolina Center for Public Health Preparedness. 4.“Focus Series: Case Finding and Line Listing: A Guide for Investigators”. Vol 1; Issue 4. UNC Chapel Hill School of Public Health North Carolina Center for Public Health Preparedness.