what's the drug patient 81562 was prescribed two times until 13 months ago?
select t1.drug from ( select prescriptions.drug, count( prescriptions.startdate ) as c1 from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 81562 ) and datetime(prescriptions.startdate) <= datetime(current_time,'-13 month') group by prescriptions.drug ) as t1 where t1.c1 = 2