Purpose: The Singapore regulatory agency for health products (Health Sciences Authority), in performing active surveillance of medicines and their potential harms, is open to new methods to achieve this goal. Laboratory tests are a potential source of data for this purpose. We have examined the performance of the Comparison on Extreme Laboratory Tests (CERT) algorithm, developed by Ajou University, Korea, as a potential tool for adverse drug reaction detection based on the electronic medical records of the Singapore health care system.
Methods:We implemented the original CERT algorithm, comparing extreme laboratory results pre-and post-drug exposure, and 5 variations thereof using 4.5 years of National University Hospital (NUH) electronic medical record data (31 869 588 laboratory tests, 6 699 591 drug dispensings from 272 328 hospitalizations). We investigated 6 drugs from the original CERT paper and an additional 47 drugs. We benchmarked results against a reference standard that we created from UpToDate 2015.Results: The original CERT algorithm applied to all 53 drugs and 44 laboratory abnormalities yielded a positive predictive value (PPV) and sensitivity of 50.3% and 54.1%, respectively. By raising the minimum number of cases for each drug-laboratory abnormality pair from 2 to 400, the PPV and sensitivity increased to 53.9% and 67.2%, respectively. This post hoc variation, named CERT400, performed particularly well for drug-induced hepatic and renal toxicities.
Discussion:We have demonstrated that the CERT algorithm can be applied across national boundaries. One modification (CERT400) was able to identify adverse drug reaction signals from laboratory data with reasonable PPV and sensitivity, which indicates potential utility as a supple- reporting from its contributors, and susceptibility to under-reporting as well as over-reporting (eg, due to media interest), (2) incomplete or missing data, hindering causality assessment, and (3) difficulty in detecting duplicate reports.
| Selection of drugs for evaluationAmong the 10 drugs analysed in the original CERT paper, one drug (ketorolac) was not used at NUH, while 3 oncologic drugs (etoposide, fluorouracil, and methotrexate) were incompletely captured because oncologic drugs are mainly ordered and recorded in another database.To have a direct head-to-head comparison of algorithm performance from the EMRs of two different health care institutions, we first analysed only 6 drugs described in the original CERT publication (round 1, Table 1).In round 2, we investigated an additional 47 drugs (Table 2).Factors considered in drug selection were drug usage volume and the likelihood of the drug being started during hospitalisation. Drugs with high usage were prioritised to provide sufficient number of cases for analysis. We also included negative controls (chlorpheniramine, metronidazole, and risedronic acid) with no ADRs detectable by abnormal laboratory test results in the reference standard.
KEY POINTSā¢ The Comparison on Extreme Laboratory Tests (CERT) algor...