Among the patients that died, what is the condition of the oldest patient?
if deathdate is not null, it means this patient died; condition refers to DESCRIPTION from conditions; the oldest patient refers to MAX(SUBTRACT(strftime('%Y', deathdate), strftime('%Y', birthdate)));
SELECT T1.DESCRIPTION FROM conditions AS T1 INNER JOIN patients AS T2 ON T1.PATIENT = T2.patient WHERE T2.deathdate IS NOT NULL ORDER BY strftime('%Y', T2.deathdate) - strftime('%Y', T2.birthdate) DESC LIMIT 1