instruction: give me the number of patients whose admission location is transfer from hosp/extram and diagnoses icd9 code is 99591?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id WHERE demographic.admission_location = "TRANSFER FROM HOSP/EXTRAM" AND diagnoses.icd9_code = "99591"