when was the last time until 11/2105 patient 52898 was prescribed a drug via the ir route?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 52898 ) and prescriptions.route = 'ir' and strftime('%y-%m',prescriptions.startdate) <= '2105-11' order by prescriptions.startdate desc limit 1