The diagnostic tool for fibromyalgia helps determine if a person meets the criteria for a diagnosis by evaluating specific conditions. Here's how it works:

- The tool considers the Widespread Pain Index (WPI) and Symptom Severity (SS) scale scores in two scenarios:
  - WPI of 7 or more and an SS score of 5 or more.
  - WPI between 3 and 6 and an SS score of 9 or more.
  
- It also considers whether the symptoms have persisted at a similar level for at least three months.
  
- Additionally, it verifies that no other disorder explains the pain.

To determine if the diagnostic criteria are met, the tool checks the following conditions:

- The first condition is met if WPI is 7 or more, SS score is 5 or more, symptoms have persisted for three months, and no other disorder explains the pain.

- The second condition is met if WPI is between 3 and 6, SS score is 9 or more, symptoms have persisted for three months, and no other disorder explains the pain.

If either of these conditions is satisfied, the tool concludes that the diagnostic criteria for fibromyalgia are met. Otherwise, it concludes that they are not met. This approach systematically uses established measurements to assess whether a fibromyalgia diagnosis is justified based on pain index, severity, duration, and exclusion of other disorders.

The calculator in question is the Diagnostic Criteria for Fibromyalgia, developed by the American College of Rheumatology (ACR). This scoring system is used specifically for patients suspected of having fibromyalgia, a chronic condition characterized by widespread pain, fatigue, and cognitive difficulties. 

The clinical utility of this calculator is to aid in the diagnosis of fibromyalgia. It takes into account factors such as the number of painful areas in the body, the severity of symptoms like fatigue, waking unrefreshed, and cognitive symptoms, and the duration of these symptoms. 

The ACR diagnostic criteria for fibromyalgia are not meant to be used in patients with another disorder that would explain the pain, such as lupus or rheumatoid arthritis. Therefore, these conditions would be considered exclusion criteria for its use.

Diagnostic criteria for fibromyalgia