instruction: how much does the weight of patient 006-161415 vary last measured on the first hospital visit compared to the second to last value measured on the first hospital visit?
response: SELECT (SELECT patient.admissionweight FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '006-161415' AND NOT patient.hospitaldischargetime IS NULL ORDER BY patient.hospitaladmittime LIMIT 1) AND NOT patient.admissionweight IS NULL ORDER BY patient.unitadmittime DESC LIMIT 1) - (SELECT patient.admissionweight FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '006-161415' AND NOT patient.hospitaldischargetime IS NULL ORDER BY patient.hospitaladmittime LIMIT 1) AND NOT patient.admissionweight IS NULL ORDER BY patient.unitadmittime DESC LIMIT 1 OFFSET 1)