NEDOCS: the emergency department overcrowding score (Weiss 2004)

NEDOCS (the National Emergency Department Overcrowding Study score) puts a number on how crowded an emergency department is at a given moment. It combines five snapshot measures: how full the ED is, how many patients are waiting for an inpatient bed, how many are on respirators and two waiting times. This NEDOCS calculator applies the Weiss 2004 formula and flags scores of 100 or more.

Not a medical device. Not a diagnosis or dosing recommendation.

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Emergency calculators
Weiss SJ et al. · 2004
The NEDOCS formula
Worked examples
Frequently asked questions

What is NEDOCS?

Weiss and colleagues built the score in academic medical centres to estimate the degree of overcrowding. It describes the department, not any one patient. The inputs are counts and hours taken at one point in time; Magent doesn't count beds, patients or wait times.

The NEDOCS formula

NEDOCS = -20
       + 85.8 × (ED patients ÷ ED beds)
       + 600 × (boarding patients ÷ hospital beds)
       + 13.4 × patients on respirators
       + 0.93 × longest admitted wait (hours)
       + 5.64 × last registration-to-bed time (hours)

rounded to 1 decimal; 100 or more is flagged overcrowded

Exact expression the calculator uses:

nedocs_score = -20 + 85.8 * (ed_patients / ed_beds) + 600 * (boarding_patients / hospital_beds) + 13.4 * respirators + 0.93 * admit_time_hours + 5.64 * reg_time_hours

Inputs

Input	Meaning	Range
`ed_patients`	All patients in the ED, including hallways	0 to 200
`ed_beds`	ED beds	1 to 300
`boarding_patients`	Patients in the ED waiting for an inpatient bed	0 to 200
`hospital_beds`	Hospital beds	1 to 3000
`respirators`	Patients on respirators in the ED	0 to 20
`admit_time_hours`	Hours since registration for the longest-waiting admitted patient	0 to 120
`reg_time_hours`	Hours from registration to bed for the last patient called from the waiting room	0 to 48

How the calculation works

Work out two ratios: ED patients over ED beds, and boarding patients over hospital beds.
Weight and add the five terms as in the formula, starting from -20.
Round to one decimal.
Flag overcrowded when the score is 100 or more.

The paper's scale runs from 0 to 200, but the calculator doesn't clamp the result, so very quiet or very busy snapshots can fall outside it. The paper's average academic ED had 50 beds and its average hospital 500 beds; the examples below use those sizes.

Worked examples

These use Magent's own expected values for the calculator. Each uses 50 ED beds and 500 hospital beds, with any input not mentioned at 0.

Example 1: two patients on respirators and nothing else

Both ratios are 0 and both times are 0.
13.4 × 2 − 20 = 6.8.
NEDOCS 6.8, not flagged.

Example 2: a full ED with 10 boarding and 2 on respirators

50 ÷ 50 = 1 and 10 ÷ 500 = 0.02.
85.8 × 1 + 600 × 0.02 + 13.4 × 2 − 20 = 104.6.
NEDOCS 104.6, flagged overcrowded.

Example 3: the same, with 5 and 7 hours of waiting

Start from Example 2 and add the two time terms.
85.8 × 1 + 600 × 0.02 + 13.4 × 2 + 0.93 × 5 + 5.64 × 7 − 20 = 148.73.
Rounded to one decimal, NEDOCS 148.7, flagged overcrowded.

History of NEDOCS

Weiss and colleagues published "Estimating the degree of emergency department overcrowding in academic medical centers: results of the National ED Overcrowding Study (NEDOCS)" in Academic Emergency Medicine in 2004. The calculator uses the paper's reduced five-variable model.

When it's used

When an ED wants to track crowding over a shift or a day with one consistent number.

Where it's used

Emergency department operations, hospital flow teams and research on crowding.

Who uses it

ED nurse leads, operations managers and researchers. The calculator does the weighting.

Limits of the calculation

It describes a department at a moment, not a patient.
The weights come from academic centres; other settings may differ.
The counts and times are taken as given.
A flag isn't an instruction to divert ambulances or change staffing.
The result isn't clamped to the paper's 0 to 200 scale.

Clinical decisions belong to a qualified clinician who knows the patient.

MEWS scores one patient's vital signs; NEDOCS scores the department.

Glossary

Boarding patient: someone admitted but still waiting in the ED for an inpatient bed.
Snapshot: counts taken at a single point in time.
Respirator: a mechanical ventilator.

Common mistakes

Using time since the admission order. The admit time runs from registration.
Leaving out hallway patients. The ED patient count includes everyone in the department.
Expecting a score between 0 and 200. The calculator doesn't clamp it.

Source

Weiss SJ, et al. Estimating the degree of emergency department overcrowding in academic medical centers: results of the National ED Overcrowding Study (NEDOCS). Acad Emerg Med. 2004;11(1):38-50. DOI: 10.1197/j.aem.2003.07.017. PMID: 14709427

Frequently asked questions

How is NEDOCS calculated?

Start at -20 and add 85.8 times the ED patient-to-bed ratio, 600 times the boarding-to-hospital-bed ratio, 13.4 per patient on a respirator, 0.93 per hour of the longest admitted wait and 5.64 per hour of the last registration-to-bed time.

What NEDOCS score means overcrowding?

The calculator flags 100 or more, the paper's overcrowding cutoff.

Is a score of exactly 100 overcrowded?

Yes. The calculator flags 100 or more, and Weiss 2004 gives 100 as the overcrowding cutoff.

Can NEDOCS be negative?

Yes. With every input at 0 the score is -20.