The hospital opiate screen was missing five patients in six

A hospital toxicology screen looks for **amphetamines, barbiturates,
benzodiazepines, cocaine, cannabis, phencyclidine and opiates**. It answers the
question it was built for and no other, which becomes a problem when what
people are taking changes.

In 2018, a multicentre study of Baltimore emergency departments showed **a
decline in the percentage of intoxicated patients testing positive for
opiates** — at a time when **opioid-involved overdose deaths in Baltimore were
increasing.**

Two numbers moving in opposite directions is not a contradiction. It means the
opioid killing people was not one the test was looking for.

The measurement that proved it

During February–April 2018, patients at one Baltimore emergency department
were tested both ways:

Five patients in six who had used fentanyl would have been recorded as opiate
negative.

The conclusion: **fentanyl alone, not in combination with heroin, was being
used more frequently** — and it was invisible.

What routine testing then showed

In late January 2019, two University of Maryland hospitals began **routine
fentanyl testing for every patient undergoing urine drug testing.**

Fentanyl was the most commonly detected drug of 2019. The pilot figures
had shown it coming: 28% in 2016, and **four of eight patients over the
2017 Memorial Day weekend.**

The design worth copying

Definitive testing — liquid chromatography-tandem mass spectrometry — can
identify a far wider range of substances, but it is **difficult to use at the
point of care and would be cost-prohibitive for every patient.**

So the Maryland Emergency Department Drug Surveillance system uses **limited
LC-MS/MS testing, triggered when patients' signs and symptoms are not
explained by routine testing** — the signal that something new is being used.

**A hybrid approach of rapid testing for the most common substances combined
with limited LC-MS/MS testing to detect emerging substances enabled
researchers and hospital systems to respond to the latest trends.**

Cheap tests for what you expect; expensive tests aimed by the cases that do
not add up. The unexplained patient is treated as information rather than as
noise.

Two limits stated plainly

The high prevalence applies to patients in Baltimore and may not generalise
to other cities or hospitals. And **immunoassays validated for fentanyl might
not detect all clinically relevant fentanyl analogues** — the same failure
mode, one generation on.

Which is why the recommendation is not "add a fentanyl test" but **"hospitals
should consider validation studies with analytical methods such as LC-MS/MS to
determine what substances are being used in their communities."** Find out what
is there, then decide what to test for.

Source: Centers for Disease Control and Prevention, MMWR.