(CNN) -- Staggering numbers of health care workers -- more than one in five -- have experienced anxiety, depression or post-traumatic stress disorder during the pandemic, new research has revealed.
Health care workers have been working for long hours under strenuous conditions. Because of this, Nathaniel Scherer, co-lead author of the systematic review and meta-analysis published Wednesday in PLOS One, said he was not surprised by the numbers.
"Previous evidence has shown that these experiences can lead to stress, fatigue and burnout, which can increase the risk of common mental disorders," said Scherer, a research assistant at the London School of Hygiene and Tropical Medicine.
Researchers analyzed 65 studies that together included over 97,000 people for the global study. Their analysis broke down the numbers by region and found health care workers in the Middle East had the highest rates of anxiety and depression, with 28.9% and 34.6% experiencing those mental health challenges, respectively.
"The Middle-East experienced a high number of patients with COVID-19, and it may be that this caseload put additional strain on healthcare professionals," Scherer said via email.
North America ranked the lowest, with 14.8% of health care workers experiencing anxiety and 18.7% experiencing depression.
However, only seven studies analyzed data from the Middle East and two from North America, so Scherer said it's important to be cautious when interpreting the results.
Researchers took the average of results from nine of the 65 studies to estimate that 21.5% of health care workers across all regions experienced moderate levels of PTSD.
But it isn't always easy for health care workers to reach out for help. CNN Chief Medical Correspondent Dr. Sanjay Gupta said last May it can be hard for people to recognize the psychological toll on frontline workers.
In his "Coronavirus: Fact vs. Fiction" podcast, Gupta said "... it's always struck me that even within the medical community, there is still a stigma about seeking therapy, seeking mental health support. Yet it's so important, maybe never more important, than it is right now."
As the pandemic progresses, Shekhar Saxena, professor of the practice of global mental health at the Harvard T.H. Chan School of Public Health, said it will be important to track these numbers over time and include data on burnout, suicide attempts and deaths, which weren't included in this study.
In addition to providing treatment and resources for health care workers, Scherer said research needs to be done on which aspects of the pandemic are causing the stresses in the first place.
"We could investigate the association between working hours and elevated symptoms as one example," he said.
Saxena, who was not involved in the study, said studying these associations can lead to "organization actions," or actions a workplace can take to create an environment that limits excessive stress.
Another part of the solution is to speak directly with health care workers to understand their struggles, he said.
The key is ensuring an approach that "values the perspective and input from healthcare professionals alongside that of expert mental health specialists," Scherer said in an email.
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