Developing a Line Listing - Engines 4 Ed



Developing a Line Listing

Traditionally epidemiologists collect data on a standard case report form or from a questionnaire. While having separate sheets for each person is necessary to gather information it often makes synthesizing the data difficult. To make this easier, epidemiologists often place information from all of the questionnaires onto one line listing. A line listing looks much like a spreadsheet, with rows and columns. Information for each case is placed on a single row. Each column represents an important variable, such as name or identification number, age, sex, case classification, etc. Critical items from the data collection forms from each case are input on the line listing for the respective case and variable. The resultant line listing contains all the key information on every case, can be scanned and updated as necessary, and makes analyzing the data much more efficient than reviewing the individual data sheets case by case.

The choice of information (variables) to use for the columns of a line listing is somewhat arbitrary and is based on the items deemed important and the hypotheses being tested for each case. The following are examples of what may be included as categories:

Identifying information:

o Identification number or case number, usually in the left-most column

o Names or initials as a cross-check

Clinical information:

o Physician diagnosis. Was diagnosis confirmed? If so, how?

o Symptoms

o Laboratory results

o Was the patient hospitalized? Did the patient die?

Descriptive epidemiology—person:

o Age, sex, race/ethnicity

o Occupation, if relevant, or other seemingly relevant characteristics

Descriptive epidemiology—place:

o Street, city, or county

o Worksite, school, day care center, etc., if relevant

Descriptive epidemiology—time:

o Date of onset

o Time of onset

Risk factors and possible causes:

o Specific to disease and outbreak setting

The importance of a good line listing cannot be overstated. It provides a log of possible and confirmed cases identified to date. At a glance one can see which cases have been interviewed and which have not, and if any information is missing. (Note: when using a line listing “n/a” for “not applicable” is used rather than leaving the cell blank to let investigators know that there is no data for that cell rather than that the information is missing and still needs collected.)

It is an efficient way to display the key data elements that all members of an investigating team can use. It is also an efficient way to review the key data elements – to scan the columns for common responses, outliers, missing data, etc. Even in the era of computers, many field epidemiologists maintain a written line listing with names and a small number of critical variables.

Sample Line Listing

|Case # |Initials |Gender |Age |Residence |Risk Factors |Labs |Lab Date |

|01234 |J.D. |F |24 |New York, NY |Mixed Martial Arts |HIV + |09 Sep 07 |

|01235 |J.C. |M |19 |Trenton, NJ |IV drug user |HIV + |15 Sep 07 |

|01236 |G.C. |M |22 |Boston, MA |None | |n/a |

Note: The blank for case 01236 shows that lab test results have not yet been received for this person while the “n/a” indicated that the Lab Date is not applicable to that case. An investigator can easily tell that case 01236 needs to be contacted about labs. Once the results were received both the Labs column and the Lab Date column would be updated.

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