How to calculate SGA score? A comprehensive guide to the Patient-Generated Subjective Global Assessment

October 6, 2025 •

3 min read

According to the Canadian Malnutrition Task Force, malnutrition affects nearly half of hospitalized patients, making accurate nutrition assessment essential. Learning how to calculate SGA score using the Patient-Generated Subjective Global Assessment (PG-SGA) is a reliable method for clinicians to identify and address malnutrition risks.

Quick Summary

The Patient-Generated Subjective Global Assessment (PG-SGA) is a validated, scored tool for determining nutritional status, particularly in clinical settings. Its score, derived from a patient-completed history and a professional physical assessment, helps classify malnutrition severity and guides intervention planning.

Key Points

Two-Part Assessment: The PG-SGA calculation involves both patient-reported history (Boxes 1-4) and a professional physical assessment (Worksheets).
Weight Loss Scoring: Box 1 scores weight changes over 1 and 6 months, with an extra point for recent loss, indicating risk.
Comprehensive Symptom Evaluation: Box 3 provides an additive score for various nutrition-impacting symptoms like nausea, vomiting, or diarrhea.
Metabolic Stress and Disease: The professional assessment considers metabolic demand from illness and factors like fever or steroid use.
Physical Exam: A clinician evaluates body composition, including fat and muscle loss, and fluid status to provide objective input.
Score-Based Triage: The final numerical score categorizes malnutrition severity (well-nourished to severely malnourished) and guides intervention triage.

What is the Subjective Global Assessment (SGA)?

The Subjective Global Assessment (SGA) is a clinical tool used by healthcare professionals to evaluate a patient's nutritional status. Originally a categorical system, it evolved into the Patient-Generated Subjective Global Assessment (PG-SGA), which incorporates a scoring system for a more precise measure of malnutrition risk, especially relevant in oncology and other patient groups. The PG-SGA considers both patient-reported details (weight changes, diet, symptoms) and a professional's physical assessment. This method provides a more comprehensive view than objective measures alone.

The PG-SGA: A Two-Part Calculation Process

The PG-SGA score is calculated in two parts: the patient completes Boxes 1-4, and a healthcare professional completes Worksheets 2-4. The final score is the sum of points from all sections.

Part 1: Patient-Generated Components (Boxes 1-4)

The patient or caregiver provides information by completing these sections:

Box 1: Weight Loss
- Scores involuntary weight loss over 1 and 6 months, assigning higher points for greater percentage loss. An additional point is given for further weight loss in the past two weeks.
Box 2: Food Intake
- Assesses changes in food intake over the past month. A significant decrease or shift to only liquids results in more points, with scores varying slightly by version. The highest score checked applies.
Box 3: Nutrition Impact Symptoms
- Lists symptoms like anorexia, nausea, vomiting, or diarrhea that affect food intake. The scores for all checked relevant symptoms are added.
Box 4: Activity and Function
- Evaluates how nutritional status impacts daily activity, from no impairment to being bedridden. The highest point value for the selected category is used.

Part 2: Professional Assessment (Worksheets)

A healthcare professional assesses the patient using objective criteria:

Worksheet 2: Disease and Age
- Considers the metabolic demands of the patient's condition and factors like age over 65, adding points for conditions such as cancer, AIDS, or trauma.
Worksheet 3: Metabolic Stress
- An additive score based on the degree of metabolic stress from factors like fever or corticosteroid use; higher doses or longer use result in more points.
Worksheet 4: Physical Examination
- Focuses on evaluating fat stores (triceps, lower ribs, orbital pads), muscle wasting (temples, clavicles, shoulders, interosseous muscles), and fluid status (ankle/sacral edema, ascites). Muscle wasting is a more significant indicator than fat loss. The results are rated on a scale of 0 to 3.

How to Compile and Interpret the Final SGA Score

The total PG-SGA score is the sum of points from all sections and helps guide nutritional intervention. The score ranges are interpreted as follows:

PG-SGA Score Categories


Score Range	Nutritional Status Category	Triage Plan (Based on Triage Score)
0–1 points	Well-nourished	No intervention required at this time; reassess regularly.
2–3 points	Mildly Malnourished	Patient education recommended, with potential pharmacological interventions.
4–8 points	Moderately Malnourished	Intervention by a dietitian is required.
≥9 points	Severely Malnourished	Critical need for immediate and aggressive nutrient or symptom management.

Using the SGA for Nutritional Triage

After calculating the SGA score, it's used to prioritize nutritional care. A higher score indicates a greater risk of malnutrition and the need for more intensive intervention. The PG-SGA also helps identify specific issues (like nutrition-impacting symptoms from Box 3) to tailor interventions, such as medication for nausea. Its effectiveness has been proven in various patient populations, highlighting its value in clinical practice.

Conclusion

Mastering how to calculate SGA score using the PG-SGA is vital for healthcare professionals. This tool provides a thorough assessment of nutritional status through both patient input and professional evaluation. The resulting score not only quantifies malnutrition risk but also directs and prioritizes nutritional interventions, contributing to improved patient outcomes and care quality. Implementing tools like the PG-SGA is fundamental to effective nutrition diet practice.

For additional information and resources on the PG-SGA, the Canadian Malnutrition Task Force website offers valuable materials here.

Frequently Asked Questions

The original SGA was a categorical assessment (A, B, C), while the Patient-Generated Subjective Global Assessment (PG-SGA) is a more detailed, scored version. The PG-SGA includes patient-reported information and provides a numerical score to guide intervention.

Weight loss is scored in Box 1 based on the percentage of involuntary weight loss over 1 and 6 months. For example, a 10% or greater loss in one month earns 4 points. An extra point is added if recent weight loss occurred in the last two weeks.

Nutrition impact symptoms, scored in Box 3 of the PG-SGA, are factors like poor appetite, nausea, vomiting, or diarrhea that interfere with a patient's food intake, absorption, or utilization. The scores for each symptom are added together.

A trained healthcare professional, such as a dietitian, nurse, or physician, performs the physical examination part of the PG-SGA. This is a subjective evaluation of body composition, including fat loss, muscle wasting, and fluid accumulation.

A total PG-SGA score of 9 or higher indicates severe malnutrition. This signals a critical need for prompt and aggressive nutrition intervention, often involving specialized support.

The PG-SGA has been validated in many populations, including cancer patients, but modifications may be required for specific groups like pediatric patients. Clinicians should ensure they are using the appropriate version for their patient group.

Several organizations provide access to the PG-SGA form and resources. The Canadian Malnutrition Task Force (CMTF) and Pt-Global offer downloadable forms and educational materials.

Yes, the Subjective Global Assessment, and especially the Patient-Generated Scored version, is a highly validated tool for assessing nutritional status. It has been shown to reliably predict clinical outcomes related to malnutrition across various patient groups.