NEDOCS Calculator

The NEDOCS score adds up five weighted parts and subtracts 20²:

• -20 (base constant)
• 85.8 × (ED patients ÷ ED beds)
• 600 × (admitted patients still in ED ÷ total hospital beds)
• 13.4 × number of ED patients on ventilators
• 0.93 × longest boarding time in hours
• 5.64 × last bed time in hours

Both time values must be in hours before you multiply them.²

A score of 100 or less means the ED is not overcrowded.³ A score of 20 or less means the ED is not busy, and above 20 up to 60 is busy.³ Above 60 and up to 100 the ED is extremely busy but not yet overcrowded.³

Above 100 the ED is overcrowded.³ Care slows down before that point. In one study, patients stayed in the ED longer at each level from busy upward, and stays were already longer than usual at extremely busy.³

Yes, both can happen. The formula starts at -20, so a nearly empty ED with no boarders can give a small negative number.² This calculator shows the negative number with the Not Busy label.

The score also has no upper limit. Scores of 200, 300, or more are possible when boarding is heavy. Anything over 180 is called dangerously overcrowded.³

Last bed time is how long the most recent patient taken from the waiting room had waited before getting a treatment bed.⁶ It is a snapshot of the current waiting room delay.

It is not the average wait and not the longest wait of the day. You look at the last person roomed and ask how long they sat in the waiting room.

Boarding is when a patient has been admitted to the hospital but is still lying in an ED bed because no inpatient bed is ready.⁵ The patient is counted as an inpatient but takes up ED space and ED nursing time.

Boarders block new patients from getting rooms,⁶ and boarding is the most important cause of ED crowding.⁷

Each boarder counts twice. Boarders are part of the ED patient count, which adds 85.8 × (ED patients ÷ ED beds), and the boarding part adds 600 × (boarders ÷ total hospital beds).² In a 40-bed ED inside a 500-bed hospital, each extra patient adds about 2.1 points and each extra boarder adds about 3.3 points.

Example: 10 boarders in a 500-bed hospital add 12 points to the boarding part, while 30 boarders add 36 points. The weights come from the original study, which matched the score to how crowded ED staff rated their department.¹

One study measured it every 2 hours,³ and some hospitals check it on the same schedule as part of their crowding plans.

One score alone means little. The trend is what matters. Checking it often shows you when crowding is building so you can act before the ED is full.

NEDOCS itself does not name a score for diversion. Each level of the score calls for a hospital response that grows as crowding rises, and hospitals write their own full capacity protocols for each level, which can cover diversion.

Scores over 180 mean dangerously overcrowded.³ Moving boarders to inpatient hallways during crowding can reduce the need for ambulance diversion.⁶

It was built and tested in academic hospitals.¹ In one lower-volume community ED it rarely reached the overcrowded range, so small and rural EDs may find the standard bands fit them poorly.³

NEDOCS has not been validated in lower-volume EDs.³ In that study, stays still grew longer as the ED moved from busy to extremely busy, so the authors advised lower-volume EDs to start crowding alerts at extremely busy instead of waiting for overcrowded.³

Both measure ED crowding, but they use different inputs.

• NEDOCS uses bed counts, ventilators, boarders, and two wait times. It rewards hospitals that move admitted patients upstairs.
• EDWIN (Emergency Department Work Index) uses the number of patients at each triage level, the number of attending doctors on duty, and the number of treatment bays minus admitted patients in the ED.⁴ It focuses on how much work the staff is carrying.

NEDOCS is the more widely used of the two.³

Yes. The ED patient count includes everyone physically in the ED: patients in rooms, in hallway beds, in doubled-up rooms, and those still in the waiting room after being registered.⁶

The bed count includes every ED bed that can be used to serve patients, hallway beds, chairs and fast track included.⁶ The census can still be larger than the bed count, because it also counts the waiting room, and that pushes occupancy over 100%.

Steven J. Weiss and colleagues developed it during the National ED Overcrowding Study.¹ They published it in Academic Emergency Medicine in 2004.¹

The team compared many possible measures against how crowded ED staff actually said their department felt, then kept the five factors that matched best.¹

The most important cause is boarding, meaning admitted patients cannot leave the ED until an inpatient bed is free.⁷ Common reasons include:

• Full inpatient units and slow discharges
• Elective surgery patients competing for inpatient beds on weekdays
• Nurse staffing shortages that close otherwise open beds
• Long waits for lab results, imaging, or specialty consults
• Delays placing patients in nursing homes or rehab

More ED visits add to crowding too, but studies point to boarding as the bigger cause.⁷

Moving boarders out lowers two parts of the score at once, since each boarder counts in both the patient count and the boarding part.² Steps that work include:

• Full-capacity protocols that move boarders to inpatient hallways
• Smoothing elective surgery schedules across the week
• Using fast track or provider-in-triage for low-acuity patients
• Bed huddles several times a day with nursing and case management

Adding ED nurses can help too, along with cutting how long admitted patients wait in the ED.²

No. Occupancy rate is just patients divided by ED beds. It is one part of NEDOCS, not the whole thing.²

Two EDs can both be at 100% occupancy, but the one with 15 boarders and an 8-hour waiting room delay will have a far higher NEDOCS score. NEDOCS adds boarding, ventilators, and wait times to show the true pressure.

In its 2012 patient flow standard, The Joint Commission recommended that boarding last no more than 4 hours after the decision to admit, in the interest of patient safety.⁸ It is a guide for hospitals setting their own goals, not a national requirement.⁸ Many quality programs measure this directly.

Long boarding is linked to medical errors and to deaths in hospital.⁷ In one study, critically ill patients who waited more than six hours for an ICU bed had higher death rates and longer hospital stays.⁷ In one large study, deaths rose from 2.5% of patients who boarded less than 2 hours to 4.5% of those who boarded 12 hours or more.⁹