The Yamaguchi diagnostic criteria for adult-onset Still's disease calculator evaluates whether a patient meets the diagnostic criteria based on user inputs regarding major and minor clinical signs.

The input consists of two sets of criteria: major criteria and minor criteria.

Major Criteria Options:
- Fever > 39 degrees C, lasting >= 1 week
- Arthralgia or arthritis, lasting >= 2 weeks
- Typical rash (a nonpruritic macular or maculopapular rash with a salmon-colored appearance, usually seen over the trunk or extremities during febrile episodes)
- Leukocytosis > 10,000/mm³, with > 80% polymorphonuclear cells

Minor Criteria Options:
- Sore throat
- Recent development of significant lymphadenopathy
- Hepatomegaly or splenomegaly
- Abnormal liver function tests (particularly aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase elevations)
- Negative tests for antinuclear antibody and rheumatoid factor

The calculator processes the input by checking the combination of selected criteria. A diagnosis of adult-onset Still's disease is indicated if:

1. There are at least 2 major criteria present, combined with at least 2 minor criteria.
2. The specific combinations of major criteria other than two may also satisfy the diagnostic requirement if they align with Yamaguchi's outlined criteria.

However, if these conditions are not met, the diagnostic criteria are not satisfied. If no selections are made, the result prompts the user to make a selection.

Here is a detailed breakdown of how the criteria are evaluated:

1. If Fever and Arthralgia/arthritis are both selected, then the presence of any combination of three minor criteria is checked.
2. If Fever and Rash are both selected, then the presence of any combination of three minor criteria is checked.
3. If Fever and Leukocytosis are both selected, then the presence of any combination of three minor criteria is checked.
4. If Arthralgia/arthritis and Rash are both selected, then the presence of any combination of three minor criteria is checked.
5. If Arthralgia/arthritis and Leukocytosis are both selected, then the presence of any combination of three minor criteria is checked.
6. If Rash and Leukocytosis are both selected, then the presence of any combination of three minor criteria is checked.
7. If combinations of three major criteria with two minor criteria are met as provided in specific patterns, this satisfies the criteria.
8. If all four major criteria are met, even one minor criterion, or any combination of two or more minor criteria, confirms the diagnosis.

The output is a straightforward result that informs whether the diagnostic criteria are met or not based on these rules and combinations.

The Yamaguchi diagnostic criteria is a clinical calculator used for the diagnosis of adult-onset Still's disease (AOSD). This scoring system applies to adult patients presenting with symptoms suggestive of AOSD, a rare systemic inflammatory disorder characterized by high spiking fevers, arthritis or arthralgia, and a distinctive salmon-colored rash.

The clinical utility of the Yamaguchi diagnostic criteria lies in its ability to help clinicians differentiate AOSD from other conditions with similar presentations, such as infections, malignancies, and other rheumatic diseases. It includes both major and minor criteria, with the diagnosis of AOSD being made if the patient meets at least 5 criteria, including at least 2 major ones.

Exclusion criteria for the use of this calculator include the presence of infections, malignancies, and other rheumatic diseases that could explain the patient's symptoms. It's important to note that the Yamaguchi diagnostic criteria is not definitive, and a high index of clinical suspicion is still required for the diagnosis of AOSD.