MDCalcLet’s face it. You’ve heard about the A-a gradient. And free water deficit. And even the APACHE-II score. But how useful are these in your daily practice? You don’t care that much if a patient has shunt physiology in the first case, nor exactly how much free water they’re lacking in the second. And in the third case, your clinical acumen is probably pretty good at predicting a sick patient’s mortality already. But what about the new medical scores of BISAP, EHMRG, and ORT?

We’ve been adding tons of equations since we launched our new MDCalc site — 20 and counting! — but we realized if you don’t know about what’s out there, you’ll never know to use it. Here are three that I find particularly useful in Emergency Medicine: 

Bedside Index for Severity in Acute Pancreatitis (BISAP) Score

Still using Ranson’s criteria? Always forgetting to add on that LDH to the sick patient with pancreatitis? You can stop. The BISAP was derived from 18,000 patients with acute pancreatitis in 2004-2005 (more recently than Ranson’s, developed in the 1970s [1]) and is at least as accurate as Ranson’s and other scoring mechanisms, yet requires fewer variables as well. This paper compared BISAP, Ranson’s, APACHE-II, and CTSI (a CT-based scoring system) and found BISAP to be as accurate as other scoring systems [2].

The BISAP score takes into account:

  • BUN>25 mg/dL
  • Impaired mental status
  • ≥2 SIRS criteria
  • Age>60
  • Presence of pleural effusion

Emergency Heart Failure Mortality Risk Grade (EHMRG)

I think clinical gestalt is frequently a good indicator of which patients presenting with heart failure exacerbation might be appropriate for ED discharge, but sometimes it’s nice to have an objective measure. Enter the EHMRG. The EHMRG was derived and validated in a Canadian population and uses vitals and a few common lab values to estimate 7-day mortality. This is exactly what we care about: Will this patient make it to their followup appointment with their primary care physician or cardiologist if I send them home? What’s even more exciting: it’s based on ED patients with heart failure – not clinic patients and not admitted patients.

There’s certainly some limitations and we’re still waiting for some external validation, but so far, this is the best study we have. With over 12,000 patients, it’s probably not too far off (with the exception of dialysis patients, who were excluded from the study). One other interesting fact — because of the calculations, it’s one of the rare scores we’ve come across that may give you a negative number. That’s correct — don’t panic — a negative score is allowed! [3]

The EHMRG score takes into account:

  • Age
  • Systolic blood pressure (initial)
  • Heart rate (initial)
  • Lowest oxygen saturation (initial)
  • Creatinine
  • Potassium
  • Transported by EMS
  • Troponin
  • Active cancer history
  • On outpatient metolazone 

Opioid Risk Tool (ORT) for Narcotic Abuse

With the alarming statistic that we’re now losing more lives to prescription drug abuse than motor vehicle collisions, it’s clear that the narcotic problem in the United States is worsening. The Opioid Risk Tool may help identify some of that abuse. With clinician gestalt not being fantastically sensitive for abuse [4], some patient risk factors might be helpful. The score was developed in patients newly visiting a chronic pain clinic — so certainly there’s going to be selection bias at work here. I’m not advocating to withhold narcotics from emergency patients with painful disease processes, but in emergency patients with chronic pain, this may help determine a course of action.  Prescription drug monitoring programs can be helpful and informative, too. Is this an exacerbation of chronic pain? Is this drug-seeking behavior? 

The ORT score factors in:

  • Gender
  • Age
  • History of preadolescent sexual abuse
  • History of depression
  • History of ADD, OCD, bipolar, or schizophrenia
  • Personal and family history of alcohol abuse
  • Personal and family history of illegal drug use
  • Personal and family history of prescription drug abuse

And one more thing on MDCalc… 

The Creatinine Clearance (Cockcroft-Gault Equation) got a facelift!

For years we’ve known that everyone’s favorite creatinine clearance calculator can be less than optimal – especially in patients who are under or over-weight, and especially in the morbidly obese. Pharmacists and nephrologists have proposed many different solutions — new equations, adjustment factors — all with varying degrees of success. Yet most people still use the tried and true Cockcroft-Gault. After discussing this with Dan Brown, a clinical pharmacist (and published author on this issue [5]), you can now optionally add in a patient’s height and get a range of creatinine clearances based on studied and validated adjustment factors, depending on the patient’s body mass index (BMI).

Hopefully we’ve given you some new ideas and ways to improve your practice. Please feel free to contact me or leave a comment if you have recommendations, suggestions, or any other ideas for MDCalc!


  1. Ranson JH, Rifkind KM, Roses DF, Fink SD, Eng K, Spencer FC. Prognostic signs  and the role of operative management in acute pancreatitis. Surg Gynecol Obstet. 1974 Jul;139(1):69-81. PubMed PMID: 4834279.
  2. Papachristou GI, Muddana V, Yadav D, O’Connell M, Sanders MK, Slivka A, Whitcomb DC. Comparison of BISAP, Ranson’s, APACHE-II, and CTSI scores in predicting organ failure, complications, and mortality in acute pancreatitis. Am J Gastroenterol. 2010 Feb;105(2):435-41. PMID: 19861954.
  3. Lee DS, Stitt A, Austin PC, Stukel TA, Schull MJ, Chong A, Newton GE, Lee JS, Tu JV. Prediction of heart failure mortality in emergent care: a cohort study. Ann Intern Med. 2012 Jun 5;156(11):767-75. PMID: 22665814.
  4. Weiner SG, Griggs CA, Mitchell PM, Langlois BK, Friedman FD, Moore RL, Lin SC, Nelson KP, Feldman JA. Clinician impression versus prescription drug monitoring program criteria in the assessment of drug-seeking behavior in the emergency department. Ann Emerg Med. 2013 Oct;62(4):281-9. PMID: 23849618.
  5. Brown DL, Masselink AJ, Lalla CD. Functional range of creatinine clearance for renal drug dosing: a practical solution to the controversy of which weight to use in the Cockcroft-Gault equation. Ann Pharmacother. 2013 Jul-Aug;47(7-8):1039-44. PMID: 23757387.
Graham Walker, MD
Emergency Physician, Kaiser San Francisco
Associate Professor of Emergency Medicine
University of California San Francisco (UCSF)
Creator and Developer of MDCalc and theNNT
Graham Walker, MD

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