Inpatient capacity margin at children's hospitals during the fall 2009 H1N1 influenza pandemic

Marion R. Sills, MD, MPH,

Objectives• Objectives:

Compare occupancy—non-ICU and ICU—during the fall 2009 pandemic to baseline numbers

Measure how close each hospital came to threshold occupancy—non-ICU and ICU

Measure how much of an increase in ED admissions it would have taken to fill each hospital (and each ICU)

Background• March 2009: “swine flu” reported with 6% case

fatality rate in Mexico; Mexico City shut down• April 2009: public health emergency declared in US• April 2010: CDC estimate of

H1N1 case fatality rate in US: 0.02% (0.006% in children 0-17 years)

H1N1 case hospitalization rate: 0.45% (0.44% in children 0-17 years)

Background• Case hospitalization

and case fatality rates much less than prior pandemics

Background• Per-population hospitalization rate

comparable to recent seasonal flu years

Methods• Inpatient data from Pediatric Health Information

System (PHIS) database• 41 children’s hospitals

Methods

Data• All hospitalizations

Non-ICU bed-days ICU bed-days

• Known # active beds

• Historic occupancy data

• All ED visits for influenza-like-illness (23 hospitals)

Calculate

• Percent occupancy by day (non-ICU, ICU)

• ED ILI admission rate

Methods• Objective 1: Compare occupancy—non-ICU and ICU—

during the fall 2009 pandemic to baseline numbers• Same weeks (35-45) for 2008 (charted below)• Seasonal flu (weeks 4-11 of 2009) for 2008-09

Methods• Objective 2: Measure how close each hospital came

to threshold occupancy—non-ICU and ICU• 2 definitions of threshold occupancy:

Normative: 100% of all active beds occupied Relative: the own-hospital 95th percentile of occupancy

(2008)

Methods• Objective 2: Measure how close each hospital came

to threshold occupancy—non-ICU and ICU How best to express this?

• Proportion of days over threshold occupancy during pandemic period?

• Some component of duration: X weeks of Y% of days over threshold?

• Number of bed-days that could have been filled daily before threshold occupancy was reached?

• Number of additional patients that could have been accepted daily before threshold occupancy was reached?

Methods

Methods• Part of the story: many children’s hospitals are

already nearing or over threshold occupancy (2006 data)

Methods Objective 3: Measure how much of an increase in ED

admissions it would have taken to fill each hospital (and each ICU)

For each hospital, calculate actual ED-to-non-ICU and ED-to-ICU admit rate among all patients with ILI

Calculate how much higher this rate would have had to be to fill all beds

Select a bad flu year (pandemic flu year? recent seasonal flu year?) and re-do the modeling for Objective 2 to show how full hospitals would have been, and how many excess beds we would have needed (i.e., how many would have boarded in the ED)

Methods Objective 3: Measure how much of an increase in ED

admissions it would have taken to fill each hospital (and each ICU)

Assumptions: • All ED-to-hospital admissions with discharge

diagnosis of ILI had H1N1 influenza• All inpatients with influenza were admitted via that

hospital’s ED• ED-to-hospital admissions were distributed evenly

throughout the study period