when was patient 84476 given for the first time a lab test since 61 months ago?
select labevents.charttime from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 84476 ) and datetime(labevents.charttime) >= datetime(current_time,'-61 month') order by labevents.charttime asc limit 1