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What do the new hospitalization metrics mean?

Almost every day we see metrics that describe how the COVID-19 pandemic affects our community, the nation, and the world. Metrics can be helpful tools to quickly share information. They can also mislead, misinform, and occasionally cause panic.

When we evaluate data, we ask ourselves some questions:

  • What question does the metric help answer?
  • How do we calculate the metric?
  • How do we collect the data?
  • Are the data complete and reliable?
  • When did we get the data?
  • What factors might influence our interpretation?
  • What’s the take home message?

Let’s apply the above questions to a real-world COVID-19 metric: the percentage of hospital beds occupied by day.

We recently shared a new section on the COVID-19 Pierce County Safe Start Metrics dashboard. The state health department uses Safe Start data to monitor each county’s progress toward re-opening. We added a Hospitalizations—Beds tab that includes two Safe Start metrics.

Hospital beds 1

What question does the metric help answer?

Many people—elected officials, public health and medical officials, the media, and the public—have expressed concern that a rapid rise in COVID-19 cases could overwhelm local hospitals and result in a shortage of hospital beds for severely ill patients. This happened in other parts of the country and nearly happened in Yakima County in late May. The question the data help to answer is How close are we to this happening in Pierce County? These metrics describe the capacity of local hospitals to treat patients in need.

How do we calculate the metric?

In both charts, the metric is the percentage of occupied beds. The top chart describes the daily percentage of beds occupied by COVID-19 patients. The bottom chart describes the percentage of beds all patients occupy, including those with COVID-19.

How do we collect the data?

Acute care hospitals in Pierce County report the data. The Washington State Department of Health (DOH) requires all hospitals report this information to the Washington Healthcare Emergency and Logistics Tracking Hub (WA HEALTH). The Washington State Hospital Association developed this database with support from DOH.

Are the data complete and reliable?

Since these are percentages and the total number of beds that might be occupied isn’t shown, we don’t know whether these metrics are based on complete information. We also don’t know if patients are Pierce County residents or not.

When did we get the data?

Hospitals reported the data within the past few weeks. The data were collected and reported differently prior to this month. We don’t have comparable data from June or before, so we don’t have a baseline to compare recent events to the past. We can’t determine whether recent events are part of a larger trend.

What factors might influence our interpretation?

Although these metrics seem straight-forward, several factors could make interpreting them challenging.

Bed occupancy is one way to measure hospital capacity. Patients also need staff, supplies, equipment, and room to maintain a safe distance from one another. Yakima County had plenty of beds but not enough staff to meet the need.

If Pierce County hospitals agree to accept patients from other counties (which they have), the percent of beds occupied could go up. The metrics don’t tell us how many local hospital beds have people from Pierce County in them.

Before the pandemic, at least half of hospital stays in Pierce County were related to elective procedures. When the pandemic hit, hospitals canceled or postponed most elective surgeries for a few months. In June, hospitals resumed scheduling these surgeries, but the timing varied from facility to facility. These changes caused the percentage of beds all patients occupy to vary for reasons other than COVID-19.

We don’t know what proportion of beds are patients requiring immediate hospitalization vs. patients who could have postponed an elective procedure. Local hospitals try to stay as full as possible without exceeding the 80% occupancy threshold for the Safe Start metric. That makes interpreting the bottom chart challenging.

What’s the take home message?

Even with these limitations, these metrics suggest that hospitals in Pierce County still have plenty of room to accommodate COVID-19 patients. Little evidence suggests a trend in bed occupancy one way or another. Most importantly, these metrics give us an opportunity to start a conversation with our local hospitals to better understand their data and their needs.

Bottom line

Metrics can be useful if you take time to understand what they mean. When evaluating metrics, make sure to ask the right questions. Our epidemiologists work hard to make sure our county has the most reliable and accurate local data—to help all of us understand how COVID-19 is affecting our community.

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