New Tool for Early Identification of COVID-19 Surges

Health systems could use data from routine clinical care to identify the onset of upcoming COVID-19 surges as many as 6 weeks before they occur, Kaiser Permanente researchers found in a study published July 26 in the journal BMJ Open.

Even though the impact on hospitals of COVID-19 cases has subsided in Northern California with successful vaccination campaigns, there are concerns that the virus and hospitalizations may surge again locally as they are elsewhere in the world, said lead author Vincent Liu, MD, MS, a research scientist with the Kaiser Permanente Division of Research.

“Over the course of 2020, COVID-19 surprised us at nearly every turn, making longer-term predictions of its impact on our patients, health system, and communities extremely challenging,” said Dr. Liu, who is also a practicing intensivist with The Permanente Medical Group and regional director of hospital advanced analytics for Kaiser Permanente in Northern California.

“At the same time, shorter-term predictions — looking only 1 to 3 weeks out — left little time to respond adequately,” he said. “By examining hundreds of millions of data points across our entire health system, we have now identified key leading indicators that forecast impending COVID-19 surges as much as 6 weeks before they hit our medical centers.”

The team tested dozens of different data elements from the electronic health record system and data used by Kaiser Permanente in Northern California to find any elements that might be indicative of an impending surge in COVID-19 admissions. To determine what data points might be leading indicators, they looked at seasonal surges of influenza as far back as 2015.

Ultimately, the investigators chose 10 indicators and determined how many weeks of lead time they could provide health system and community officials. While individual indicators could forecast an upcoming surge in the next 1 to 3 weeks, the combined CHOTS — the “COVID-19 HotSpotting Score” — significantly increased the lead time to as far as 6 weeks prior to a surge.

CHOTS includes 4 major variables — cough and cold calls, relevant subject headers from patient emails, positive COVID-19 test rates, and current COVID-19 hospital census — along with 6 minor variables, including COVID-19-related calls to the call center, both routine and urgent clinic visits for respiratory infections, clinic and urgent clinic COVID-19 visits, and respiratory virus tests ordered.

Public health officials and individual health systems could use the information to boost local testing, expand contact tracing, adjust policy measures, and prepare expanded hospital space and supplies for anticipated patients. The authors found early indicators of waning COVID-19 activity were also valuable because they could help identify when relief from the surge of COVID-19 was on the horizon.

“The development of CHOTS is an inspiring example of how Kaiser Permanente’s integrated care delivery system and robust research capabilities can come together to provide the greater community with vital public health tools,” said co-author Stephen Parodi, MD, national infectious disease leader for Kaiser Permanente. “What is even more impressive is that this work was carried out while our medical centers were caring for large numbers of COVID-19 patients. Our researchers worked alongside operational leaders to better prepare our management of future surges.”