instruction: how many patients whose diagnoses icd9 code is e8859 and drug type is additive?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id WHERE diagnoses.icd9_code = "E8859" AND prescriptions.drug_type = "ADDITIVE"