Your Easy Guide to Clinical Studies

Calculated Fields are programmed functions in the eCRF that convert data into a more useful format or required information (e.g. age at study start, BMI based on height and weight). Calculated fields have an important advantage, as they are processed automatically and therefore eliminate human calculation errors.

Required calculations can be done either when the data is entered in the study database (pre-processing) or after being exported (post-processing)

 

Calculated Fields require:

• An electronic database (e.g. CDMS)
• Ability to program calculations (e.g. formula, classification)
• Validation procedures to ensure automated processing was correctly implemented

 

Example

Calculation of creatinine clearance requires the input of raw data into an applicable formula (age, weight, serum creatinine, and gender). Upon automated data processing the creatinine clearance number is no longer raw data (e.g. source data) but automated processed data.

As a SP-INV, and based on data needed to answer your study question:

• Make a list of study data (variables) that can be obtained through automated processing

 

For pre-processing:

• Define which variables must be available
• Ask your data manager to program the required calculation(s) in the study database
• If needed, implement alerts for upper and lower calculation limits
• Include a test phase to guarantee that pre-processing calculations are correctly implemented. Document the implemented validation procedures

 

For post-processing:

• Define which variables must be available for data export (e.g. for analysis)
• Ask your data manager or statistician to program the required calculation(s) based on the raw data
• Include a test phase to guarantee that post-processing calculations are correctly implemented Document the implemented validation procedures

 

Describe the Calculated Fields in the DMP and/or SAP

References

ICH GCP E6(R3) – see in particular principle and guideline

• Principle 9: Clinical trials should generate reliable results
• 4.2.2 (iii) Relevant metadata including audit trail. Data change into the system