Subjective Global Assessment (SGA)

The Subjective Global Assessment (SGA) is a clinician-administered method for classifying nutritional status from history and physical examination rather than from laboratory values. It combines features of recent weight change, dietary intake, gastrointestinal symptoms, functional capacity, and a focused physical exam into an overall rating of well-nourished, moderately malnourished, or severely malnourished.

Definition

SGA is a structured clinical rating of nutritional status, derived from a patient's history (weight change, intake, symptoms, function, disease stress) and physical examination (loss of subcutaneous fat, muscle wasting, oedema), that yields a global category rather than a numeric score.

Scope

The entry describes the structure and rationale of SGA, the clinical features it integrates, and its place as a reference standard against which newer screening tools are often compared. It treats SGA as a methodological topic in nutritional assessment, not as clinical instruction.

Key concepts

• Clinical (subjective) judgement of nutritional status
• Weight change history
• Dietary intake change
• Gastrointestinal symptoms
• Functional capacity
• Physical signs: subcutaneous fat loss, muscle wasting, oedema
• Global rating (A, B, C)
• Patient-Generated SGA (PG-SGA) adaptation

Mechanisms

SGA works by having a trained rater integrate several history items - the amount and pattern of weight loss, change in dietary intake, persistent gastrointestinal symptoms, functional impairment, and the metabolic demand of the underlying disease - with a physical examination for loss of fat stores, muscle wasting, and fluid signs. Rather than summing points, the rater forms an overall clinical impression and assigns one of three categories. Detsky and colleagues showed that experienced raters could apply this judgement with acceptable reproducibility, which underpins its continued use as a comparison standard.

Clinical relevance

SGA is widely used as a reference method for nutritional status in research and is one of the assessment approaches recognized within the GLIM diagnostic framework. As a reference topic it explains how a structured clinical judgement of nutrition is formed; it is descriptive and does not provide individualized diagnostic cut-offs or treatment guidance.

Epidemiology

SGA has been applied and studied across hospital inpatients, surgical patients, oncology, dialysis, and other populations, and is frequently used as the comparator when the validity of quicker screening tools is examined. The Patient-Generated SGA extends it for oncology by adding patient-completed sections.

History

SGA grew directly out of Baker and colleagues' 1982 demonstration that clinical judgement could classify nutritional status reproducibly. Detsky and co-workers formalized the method in 1987, defining the history and examination features and the three-category rating. Ottery later adapted it as the Patient-Generated SGA for oncology, and the 2019 GLIM consensus situated SGA-type assessment within a harmonized approach to diagnosing malnutrition.

Debates

Is SGA's subjectivity a strength or a limitation?

Its reliance on clinical judgement allows integration of many cues but depends on rater training and experience, raising questions about reproducibility between assessors compared with fixed-score tools.

Key figures

• Allan Detsky
• Khursheed Jeejeebhoy
• John Baker
• Faith Ottery

Seminal works

• baker-1982
• detsky-1987

Frequently asked questions

How does SGA differ from a scored screening tool?

SGA produces an overall clinical category (A, B, or C) from integrated history and examination findings rather than a summed numeric score, so it depends on the rater's structured judgement.

What is the Patient-Generated SGA?

It is an adaptation of SGA for oncology, described by Ottery, that adds patient-completed sections on weight, intake, symptoms, and function to the clinician's assessment.