Case Control Study

Data
Collection

Step 5: Data Collection

With the design of the case-control study complete, you now begin planning the protocol for data collection.

4.	What is the best source for gathering information on the disease (case) status? [See Gordis, Ch.3, pg. 35-36]
		a.	diagnosis of Susser Syndrome identified from the hospital charts of the local hospital and based on the neurology consultation and supported by lab results.
		b.	complaints of neurological symptoms identified from the records of Superfit staff nurse
		c.	complaints of neurological symptoms based on information provided by Superfit Membership Directory Office about medical leaves of absence of club members

5.	From where should the disease status data be collected? [See Gordis, Ch.3, pg. 31-38]
		a.	look through the records of the local hospital dated from September, 2000 to September, 2002 to identify those with the disorder and see if there is information in the chart about their membership to Superfit
		b.	link a computer database containing the names of Superfit members with the discharge database from the local hospital

You decide that cases will be recruited using the hospital discharge data cross-referenced with a membership directory provided by the Superfit Fitness Center. Cases meeting the eligibility criteria will then be telephoned and asked to participate.

6.	What is the best way to accrue the controls? [See Gordis, Ch.9, pg 143-148]
		a.	Using hospital discharge data, you will find subjects with a diagnosis of anything but Susser Syndrome. These subjects will then be cross-referenced with the Superfit membership directory and contacted via the telephone.
		b.	You will take a random sample from the complete list of all members listed in the Superfit directory and determine their eligibility criteria. Those eligible will be asked to participate by phone. If they agree to participate, an interview will be scheduled.

You must also decide how you will assess the exposure variable in this case-control study. The exposure variables of interest are the ingestion of Quench-it or the consumption of Endurobrick.

7.	Given the study design, what is the best way to assess the exposure variable? [See Gordis, Ch.3, pg. 37; Ch.18, pg. 283-285]
		a.	Directly observe the ingestion or consumption of Endurobrick and Quench-it at Superfit.
		b.	Find and test for a biological marker, such as gut enzyme level, that would serve as a surrogate exposure variable, indicating the ingestion or consumption of Endurobrick and Quench-it.
		c.	Question all of the subjects as to their own assessment of Endurobrick and Quench-it intake using a standardized survey tool.
		d.	Use the tally employed by the fitness center credit card to bill the members for their consumption of Endurobrick and Quench-it.

Your supervisor reads over your recommendations and agrees with your suggestions. Before the study can begin and the data can be collected, however, your supervisor instructs you of all the administrative work that must be in order. You must:

Get approval of your study from your Institutional Review Board (IRB) - this will ensure that the study adheres to the ethical principles of conducting public health research and that the rights of study participants are protected.
Prepare a budget and get funding.
Develop an operations manual to be used by all study personnel which will describe the standardized procedures for collecting data, managing data, etc. This is used to ensure quality control.
Design a consent form for study participants - it should clearly indicate your goals; it should also explain risks, benefits and expenses that participants might incur if they decide to participate in your study; it should also state how participants would benefit from their participation and how you plan to make use of the data once it is collected.
Design a questionnaire that will be used to collect data from the study participants.
Hire and train interviewers.
Design a data management plan (how and where paper forms will be stored, when and how they will be entered into computer database, when periodical checks of the data will be performed to spot possible problems in the study).
Design data analysis plan and think about publicizing your findings.

Having received the necessary IRB approval, the study starts. The data begin to file back to the Department of Health and must now be collated and carefully entered into the computer database. Despite your leadership role, you are still the intern and thus have the inglorious yet crucial responsibility of data entry. Once all of the data are entered, you can proceed to the analysis stage where the associations stated in your 2 hypotheses are characterized and tested.

Learning
Objectives

Introduction
to Study

Data
Collection