2.2 Construction and performance evaluation of active
surveillance programs
The CHPS Drug Evaluation System (Figure 2) is one of the subsystems in
the CHPS. It can obtain seven dimensions of clinical information from
HIS, including patient retrieval (basic information of patients), test
retrieval (test items, test values), medical order retrieval (drug ID),
medical record retrieval (admission records, progress notes), diagnosis
retrieval, physical sign retrieval, and examination retrieval, these
seven dimensions can be easily connected with each other by Boolean
logic operators. In this study, we used Boolean logic programming for
triggers in medical orders, diagnoses, and progress notes to form
retrieval rules. To improve the positive rate, the triggers in the
progress notes and medical orders were connected by ”AND”. The rules
were then run on the discharged patients to identify and analyze cases
with positive triggers but not anaphylaxis, and exclusion rules were set
accordingly to improve triggers performance. Finally, active
surveillance programs were constructed by combining search rules and
exclusion rules (Figure 3).
The positive predictive value (PPV) of the active surveillance programs
was calculated as the number of anaphylaxis cases detected by active
surveillance programs divided by the number of cases with positive
triggers. The incidence of anaphylaxis was calculated as the number of
anaphylaxis cases detected by active surveillance programs divided by
the number of discharged patients. The performance of the active
surveillance programs compared with the spontaneous reporting system was
expressed as cases of anaphylaxis detected by active surveillance
programs divided by reports of anaphylaxis in the spontaneous reporting
system in the same period.