All subjects recruited from general population will be identified by a unique code. Number and capital letters code will be placed in the survey and in the sample labels as M0001 (M: city, number 0001: person number 0001). Data will be uploaded and saved in a secure data base. Trained personnel will be in charge of handling the data base. Investigators will supervise the data entry. An investigator at least once every 6 months will randomly select 2% survey and will match it against the information uploaded in the database. Furthermore, investigators will analyze and report all collected data from the surveys even if they are incomplete by adjusting the analysis parameters of the incomplete ones.