The Nutrition Risk Screening 2002 (NRS 2002) tool evaluates an individual's nutritional risk by considering four critical input factors: initial screening criteria, nutritional impairment, severity of disease, and age. Each factor's response corresponds to a predefined score that contributes to the overall risk assessment, guiding the necessary nutritional interventions.

Here's how the scoring works:

- **Initial Screening**: All options under this category result in a score of 10, whether the criterion is a body mass index under 20.5 kg/m², recent weight loss, reduced dietary intake, or being in an intensive care unit.

- **Nutritional Impairment**:
  - "None" scores 0.
  - "Weight loss > 5% in 3 months or food intake < 50-75% of normal in the past week" scores 1.
  - "Weight loss > 5% in 2 months or body mass index 18.5-20.5 kg/m² with impaired general condition or food intake 25-60% of normal in the past week" scores 2.
  - "Weight loss > 5% in 1 month or > 15% in 3 months, or body mass index < 18.5 kg/m² with impaired general condition or food intake 0-25% of normal in the past week" scores 3.

- **Severity of Disease**:
  - "Normal nutritional requirement" scores 0.
  - "Conditions like hip fracture, chronic illnesses with potential acute complications, chronic dialysis, diabetes, or cancer" score 1.
  - "Major abdominal surgery, stroke, severe pneumonia, hematologic malignancy" score 2.
  - "Head injury, bone marrow transplant, or intensive care unit patient with APACHE > 10" score 3.

- **Age**:
  - "< 70 years" scores 0.
  - ">= 70 years" scores 1.

The total score is calculated by summing the scores from each category. This cumulative score corresponds to specific nutritional risk categories with different interpretations and recommendations.

Interpretation of Scores:
- Scores up to 7 indicate a "Low risk."
- Scores of 10, 20, 30, and 40 suggest "Low risk" with a recommendation for weekly re-screening.
- Scores of 11, 21, 31, and 41 represent "Low risk" with weekly re-screening advised.
- Scores of 12, 22, 32, and 42 continue to denote "Low risk" prompting weekly review.
- Scores of 13, 23, 33, and 43 keep the individual in the "Low risk" category with a need for weekly assessment.
- Scores of 14, 24, 34, and 44 indicate the individual is "At risk," necessitating a tailored nutritional care plan involving food, oral supplements, tube feeding, or parenteral nutrition as suitable.
- Scores of 15, 25, 35, and 45 represent "High risk," prompting the initiation of an early nutritional care plan.
- Scores of 16, 26, 36, and 46 suggest "High risk," warranting immediate nutritional intervention.
- Scores of 17, 27, 37, and 47 indicate "High risk," requiring prompt implementation of a nutritional care plan.

The Nutrition Risk Screening 2002 (NRS 2002) is a clinical calculator used to assess the risk of malnutrition in hospitalized adult patients. It is particularly useful in identifying patients who may benefit from nutritional intervention, thereby improving their clinical outcomes and reducing hospital stay. The NRS 2002 takes into account factors such as age, body mass index, weight loss, dietary intake, and severity of disease. It is not recommended for use in children, pregnant women, or patients with certain conditions such as edema or ascites, which can affect weight and therefore skew the results.