Inaccurate medical records and poor medication adherence result in incomplete knowledge of therapy patterns among patients. Researchers have developed an assay test capable of accurately measuring 263 prescribed and over-the-counter medications in a single blood sample. Applied clinically, an analysis showed that non-adherence was common and that the electronic health record (EHR) medication list often did not agree with detected medications.

While 78% to 100% of medications were detected as prescribed in the electronic health record medication list, 63.0% of patients had a discrepancy between the medical record and detected medications. Also, almost half of the drugs that triggered drug–drug interaction alerts in the study involved medications not listed in EHRs.

The cross-sectional study analyzed samples of more than 1,300 patients involving three care settings: residual serum, gastroenterology care and emergency department. Researchers found that adherence was higher in prospectively enrolled patients (the gastroenterology cohort) than in retrospectively tested patients (residuals cohort and ED care cohort). Opioids and diazepam were the most common medications that were detected despite lack of evident prescription.

Researchers concluded that (1) medications can be frequently detected despite lack of prescription evidence in the EHR, (2) patient adherence varies by health care setting, (3) being adherent to one medication is a positive determinant of adherence to other medications and (4) drug-drug interactions were common and occurred more frequently among patients with medications that were detected but not prescribed.