Seasonal temperature impacts patient lab results

Date:
December 10, 2021
Source:
Cell Press
Summary:
Ambient temperature influences the results of some of the most used
laboratory tests, and these distortions likely affect medical
decision making, such as whether to prescribe medications,
researchers report. The authors say that laboratories could
statistically adjust for ambient temperature on test days when
reporting lab results to account for day- to-day variability.



FULL STORY ========================================================================== Ambient temperature influences the results of some of the most used
laboratory tests, and these distortions likely affect medical decision
making, such as whether to prescribe medications, researchers report
December 10th in the journal Med. The authors say that laboratories
could statistically adjust for ambient temperature on test days when
reporting lab results to account for day- to-day variability.


========================================================================== "When a doctor orders a laboratory test, she uses it to shed light on
what's going on inside your body, but we wondered if the results of those
tests could also reflect something that's going on outside of your body"
says study co- author Ziad Obermeyer (@oziadias) of the University of California, Berkeley.

"This is exactly the kind of pattern that doctors might miss. We're not
looking for it, and lab tests are noisy." To explore this question,
Obermeyer and Devin Pope of the University of Chicago analyzed a large
dataset of test results from 2009 to 2015, spanning several climate
zones. In a sample of more than four million patients, they modeled
more than two million test results as a function of temperature. They
measured how day-to-day temperature fluctuations affected results,
over and above the patients' average values, and seasonal variation.

The results showed that temperature affected more than 90% of individual
tests and 51 of 75 assays, including measures of kidney function, cellular blood components, and lipids such as cholesterol and triglycerides. "It's important to note that these changes were small: less than one percent differences in most tests under normal temperature conditions,"
Obermeyer says.

These small, day-to-day fluctuations did not likely reflect long-term physiological trends. For example, lipid panels checked on cooler days
appeared to suggest a lower cardiovascular risk, leading to almost
10% fewer prescriptions for cholesterol-lowering drugs called statins
to patients tested on the coolest days compared to the warmest days,
even though these results probably did not reflect stable changes in cardiovascular risk.

Because the study wasn't an experiment, the researchers could not pinpoint
the exact mechanisms underlying the fluctuations in lab results. Possible explanations include blood volume, specific assay performance, specimen transport, or changes in lab equipment. "Whatever their cause, temperature produces undesirable variability in at least some tests, which in turn
leads to distortions in important medical decisions," Pope says.

One practical implication of the study is that laboratories could
statistically adjust for ambient temperature on the test day when
reporting lab results.

Doing so could reduce weather-related variability at a lower cost than
new laboratory assay technology or investments in temperature control
in transport vans. In practice, decisions on adjustment would need to
be at the discretion of the laboratory staff and the treating physician, potentially on a case-by- case basis.

According to the authors, the study may also have broader clinical implications. "The textbook way of thinking about medical research
is bench to bedside. First, we come up with a hypothesis, based on
theory, then we test it with data," Obermeyer says. "As more and
more big data comes online, like the massive dataset of lab tests we
used, we can flip that process on its head: discover fascinating new
patterns and then use bench science to get to the bottom of it. I think
this bedside-to-bench model is just as important as its better-known
cousin because it can open up totally new questions in human physiology." ========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Ziad Obermeyer, Devin Pope. Variation in common laboratory test
results
caused by ambient temperature. Med, 2021; 2 (12): 1314 DOI:
10.1016/ j.medj.2021.11.003 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211210113019.htm

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