During data entry, data is stored on two external hard disks and the principal investigator's computer in the control of the principal investigator. Data on the Test Mate ChE Cholinesterase System is automatically deleted when the power is switched off. Every week a full backup of the data file will be saved on a USB stick placed outside research establishments under the principal investigator's control until the data entry is complete. Data editing and analysis will be based on a data file without sensitive information (like name, address and phone number). The data file will be saved on an external hard disk, USB stick and the principal investigator's computer drop box on a daily basis and kept under secure conditions and with only access to the principal investigator.