instruction: how many patients whose drug code is atro1i and lab test category is hematology?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE prescriptions.formulary_drug_cd = "ATRO1I" AND lab."CATEGORY" = "Hematology"