Hi,

I am trying to identify the date when a drug reached Phase III in the clinical trial process. My data is in the form of a string (example below). I want two things:
1. to extract the earliest date that starts with 19. So in the example below that would be 1984
2. to extract all dates that start with 19.., split into a separate column for each date. So, the example below, I would ideally have two new columns for the three dates (since 1988 is repeated) - 1st with 1984, 2nd with 1988

"It was effective in: sarcoidosis; severe herpes simplex infections (1st World Conf Inflamm Antirheum Analg Immunomod (Venice), 1984, 140-147); secondary immunodeficiency after major surgery (1st Int Cong Imm Conseq Trauma Shock Sepsis (Munich), 1988, Abs OR45); psoriasis (3rd Eur Symp Psoriasis (Trieste), 1988, P32)"

Any guidance would be much appreciated!

Thanks,
Karishma