when did patient 86786 last receive until 8 months ago a prescription for hydrochlorothiazide?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 86786 ) and prescriptions.drug = 'hydrochlorothiazide' and datetime(prescriptions.startdate) <= datetime(current_time,'-8 month') order by prescriptions.startdate desc limit 1