when was patient 52898 for the last time prescribed a medication via the right ear route since 176 months ago?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 52898 ) and prescriptions.route = 'right ear' and datetime(prescriptions.startdate) >= datetime(current_time,'-176 month') order by prescriptions.startdate desc limit 1