Extracts the first test only per patient

SurveilFirstTest(dataframe, HospNum_Id, Endo_ResultPerformed)

Arguments

dataframe

dataframe

HospNum_Id

Patient ID

Endo_ResultPerformed

Date of the Endoscopy

Examples

dd<-SurveilFirstTest(Myendo,'HospitalNumber', 'Dateofprocedure')