December 19, 2017

SGA and ASPEN: Diagnosing Malnutrition

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Key criteria govern the search to determine whether a patient is malnourished.

EDITOR’S NOTE: The following is a summary of a transcript of Pamela Charney speaking during a recent edition of Talk-Ten-Tuesdays.

Right now folks are looking at the American Society for Parental and Enteral Nutrition (ASPEN) consensus criteria for diagnosing malnutrition. Those criteria rely heavily on something called the Subjective Global Assessment.

The Subjective Global Assessment (SGA) was first published in 1982 by Drs. Baker and Detsky in the New England Journal of Medicine. What they realized is that a lot of the information that is included in the history and physical (H&P) could be used to diagnose malnutrition, and this could be done without relying on expensive lab tests and the identification of symptoms that don’t really indicate the presence of the condition. They wanted to find criteria that directly related to nutritional status.

So SGA was born in 1982, and since then it’s been validated many, many times. What I’d like to do today is go over some of the criteria that were used in the SGA.

First, SGA consists of five criteria from the medical and surgical history and another set of criteria focusing on physical ability. So this is where it diverges from the ASPEN criteria.

ASPEN relies heavily on hand grip strength, as measured by a hand grip strength dynamometer. However, that particular test has never been validated to be an indicator of nutritional status. It’s used in the fields of occupational therapy and physical therapy.

So the SGA begins with a look at the history. It begins with a look at the weight change, because we know that malnutrition happens when nutrient intake doesn’t meet nutrient requirements over some period of time.

More specifically, this involves a look at both an acute and chronic level of weight change. Has the patient has lost weight over the past six months, and if so, how much? It also centers on weight change in the past two weeks.

So these are questions that can be answered relatively quickly during the patient’s history. The next criteria involve something that physicians are sometimes a little bit nervous about checking, and this is where a registered dietician (RD) can come into play. All the physician has to ask is this: “have you been eating the same as you normally eat?”

As with weight change, the intent is to determine whether there has been any notable shift. Was the patient able to eat a solid diet? Was the patient relegated to a liquid diet? Is the patient eating at all? If there was a change, there should be a referral to the RD to follow up with that.

The next criteria from the history are gastrointestinal symptoms that persist for greater than two weeks. This helps us get past those folks who simply have a very acute, limited experience of diarrhea or vomiting. Here we are looking for symptoms such as nausea, vomiting, diarrhea, or anorexia: gastrointestinal (GI) symptoms that keep someone from eating normally.

The next criteria are functional capacity. When I was in the Army, we used to ask, “can you still walk to the mailbox?” “Are you able to get (this was before we had remote controls) up and change the channel on your TV?” So this looks at if the person is able to perform activities of daily living without assistance. It looks at whether there is some dysfunction, and then, again, how for long. “Are you able to walk or are you not able to walk?”

Again, this takes into account some chronic or acute illness that may impact nutritional status.

Finally, the SGA involves a physical exam to probe for subcutaneous fat loss, muscle wasting, edema, and ascites. Finally, all this information is put together so the clinical can make a subjective assessment of whether the patient is well-nourished or has some degree of malnutrition. If this is done as part of the history and physical and there is something that indicates malnutrition, a referral to the RD should be made.

So that is basically the criteria involved in the SGA and how it correlates with the ASPEN consensus criteria.
Pamela Charney, PhD, RD

Pamela Charney is a clinical informaticist and a U.S. Army veteran. She is also a registered dietitian and has more than 25 years of experience in nutrition support, critical care, management, and nutrition informatics. She is the co-editor of the popular Pocket Guides to Nutrition Assessment, Enteral Nutrition, and Parenteral Nutrition. She is a recognized expert in nutrition assessment and the nutrition care process.

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