instruction: what was last lab test time during this month for patient 4401?
response: SELECT labevents.charttime FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 4401) AND DATETIME(labevents.charttime, 'start of month') = DATETIME(CURRENT_TIME(), 'start of month', '-0 month') ORDER BY labevents.charttime DESC LIMIT 1