count the number of patients who were diagnosed with acute necrosis of liver in the same hospital visit after they were diagnosed with nb obsrv suspct infect during this year.
select count( distinct t1.subject_id ) from ( select admissions.subject_id, diagnoses_icd.charttime, admissions.hadm_id from diagnoses_icd join admissions on diagnoses_icd.hadm_id = admissions.hadm_id where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'acute necrosis of liver' ) and datetime(diagnoses_icd.charttime,'start of year') = datetime(current_time,'start of year','-0 year') ) as t1 join ( select admissions.subject_id, diagnoses_icd.charttime, admissions.hadm_id from diagnoses_icd join admissions on diagnoses_icd.hadm_id = admissions.hadm_id where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'nb obsrv suspct infect' ) and datetime(diagnoses_icd.charttime,'start of year') = datetime(current_time,'start of year','-0 year') ) as t2 on t1.subject_id = t2.subject_id where t1.charttime < t2.charttime and t1.hadm_id = t2.hadm_id