hey what was patient 86792's average chloride value until 10 months ago?
select avg(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 86792 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'chloride' ) and datetime(labevents.charttime) <= datetime(current_time,'-10 month')