instruction: what was the last value of an chloride lab test in patient 84346 until 51 months ago?
response: SELECT labevents.valuenum FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 84346) AND labevents.itemid IN (SELECT d_labitems.itemid FROM d_labitems WHERE d_labitems.label = 'chloride') AND DATETIME(labevents.charttime) <= DATETIME(CURRENT_TIME(), '-51 month') ORDER BY labevents.charttime DESC LIMIT 1