count the number of patients who were prescribed thiamine in the same month after receiving a parent infus nutrit sub procedure since 5 years ago.
select count( distinct t1.subject_id ) from ( select admissions.subject_id, procedures_icd.charttime from procedures_icd join admissions on procedures_icd.hadm_id = admissions.hadm_id where procedures_icd.icd9_code = ( select d_icd_procedures.icd9_code from d_icd_procedures where d_icd_procedures.short_title = 'parent infus nutrit sub' ) and datetime(procedures_icd.charttime) >= datetime(current_time,'-5 year') ) as t1 join ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'thiamine' and datetime(prescriptions.startdate) >= datetime(current_time,'-5 year') ) as t2 on t1.subject_id = t2.subject_id where t1.charttime < t2.startdate and datetime(t1.charttime,'start of month') = datetime(t2.startdate,'start of month')