is there a history of a microbiology test performed on patient 96833 since 6 years ago?
select count(*)>0 from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 96833 ) and datetime(microbiologyevents.charttime) >= datetime(current_time,'-6 year')