indicate the monthly maximum arterial bp [systolic] of patient 1561 since 08/01/2105.
select max(chartevents.valuenum) from chartevents where chartevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 1561 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'arterial bp [systolic]' and d_items.linksto = 'chartevents' ) and strftime('%y-%m-%d',chartevents.charttime) >= '2105-08-01' group by strftime('%y-%m',chartevents.charttime)