Our team has been doing a full review of outpatient / inpatient / transfer stats from our department's perspective for Jan-Mar 2012, which was a time period where we saw an epidemic of human metapneumovirus (hMPV) that overlapped an unusually severe season of RSV. We have issued several reports of our experience here in this blog.
The forecast, initially released by the Ascel Bio Black Canyon Infectious Disease Forecasting Station in Nov (i.e. 60 days before the onset of RSV and non-RSV activity), indicated we would see RSV activity precede non-RSV (i.e. human metapneumovirus, hMPV). We should have expected higher RSV activity than MPV in Jan.
What actually happened:
More MPV activity in Jan than RSV, with RSV exhibiting nearly zero activity (grossly unusual based on prior baselines, as indicated by the forecast). This tipped us off immediately we were seeing something not observed at least in the last 5 years. We were the first in the nation to publicly declare the possibility of a "bad" / unusual season of RSV/MPV; this was confirmed by multiple pediatric intensive care units in many other states.
Our department saw +180%, +213%, and +180% hospital admissions for the months of Jan, Feb, and Mar 2012, respectively, based on prior baselines. From the perspective of total pediatric admissions for Jan-Mar inclusive, we saw a difference of +238%.
From the perspective of transfers from inpatient care to an outside facility (i.e. due to level of acuity), we transferred +100%, +746%, and +150% for the months of Jan, Feb, and Mar 2012, respectively, based on prior baselines. The expected average transfer rate for Jan-Mar, inclusive, was 7%. What we saw in Jan-Mar 2012 was 13% (an increase in clinical acuity of 186%).
The unusually high clinical acuity triggered a change in clinical protocol based on report of bacterial coinfection (e.g. Haemophilus influenzae, among other)- we are still analyzing the data to see if there is an inference of transfer avoidance after implementing this protocol. It is notable that the number of transfers for Jan-Mar 2012 was +160% over the combined transfers for Jan-Mar 2009, 2010, and 2011, and +480% over the expected average annual Jan-Mar period.
1. The 2012 RSV / MPV season broke all available hospital records in terms of admission volume and clinical severity.
2. The forecast was accurate, and highlighted a subtle difference in the 2012 disease activity signature that empowered us to rapidly recognize unusual disease activity early in the season involving RSV and MPV. This then empowered us to alert colleagues nationwide about a change in RSV/MPV activity.