Cdai (Clinical Disease Activity Index) Calculator

The CDAI Calculator is a tool used to calculate the Clinical Disease Activity Index (CDAI) score, which is a measure of disease activity in patients with rheumatoid arthritis (RA). It takes into account the number of tender and swollen joints, as well as the assessments provided by both the patient and the physician regarding the overall disease activity.

By calculating the CDAI, the tool helps clinicians assess how active the disease is and make necessary treatment adjustments. Patients can also use the CDAI Calculator to monitor their disease activity over time and discuss their progress with their healthcare providers.

Formula for Calculating CDAI

The CDAI is calculated using a formula that incorporates four key factors:

CDAI = (Tender Joint Count) + (Swollen Joint Count) + (Patient Global Assessment) + (Physician Global Assessment)

Where:

• Tender Joint Count: The number of joints that the patient reports as tender, typically assessed from a 28-joint examination.
• Swollen Joint Count: The number of joints that are observed to be swollen, also based on a 28-joint examination.
• Patient Global Assessment: A self-reported score by the patient regarding their perceived disease activity, rated on a scale from 0 to 10.
• Physician Global Assessment: A score provided by the physician based on their assessment of the disease activity, also rated on a scale from 0 to 10.

Each of these factors contributes to the overall disease activity score, which helps in determining the appropriate course of treatment and management.

CDAI Score Interpretation

Once the CDAI score is calculated, it can be interpreted to assess the severity of the disease. The CDAI score is categorized into four disease activity levels:

• Remission: CDAI ≤ 2.8
  • Indicates minimal or no disease activity. This suggests that the patient’s disease is under control or in remission.
• Low Disease Activity: 2.8 < CDAI ≤ 10
  • Indicates mild disease activity, where symptoms are present but not severe.
• Moderate Disease Activity: 10 < CDAI ≤ 22
  • Indicates moderate disease activity, with more noticeable symptoms and some functional impairment.
• High Disease Activity: CDAI > 22
  • Indicates severe disease activity, with significant symptoms and potential for joint damage or other complications.

This classification helps doctors determine whether the current treatment plan is effective or needs adjustment.

General Terms Table

Here are some key terms associated with the CDAI calculation:

Term	Definition
Tender Joint Count	The number of joints that the patient reports as painful or tender, typically from a 28-joint assessment.
Swollen Joint Count	The number of joints that are swollen, as identified by a physician during a clinical exam.
Patient Global Assessment	The patient’s self-assessment of their overall disease activity, rated from 0 (no activity) to 10 (worst possible activity).
Physician Global Assessment	The physician’s assessment of the overall disease activity, also rated from 0 to 10.
CDAI Score	The total score derived from the above components, used to classify the disease activity.

Example of Using the CDAI Calculator

Let’s consider an example to illustrate how the CDAI Calculator works.

Example:

• Tender Joint Count: 5 (out of 28 joints)
• Swollen Joint Count: 4 (out of 28 joints)
• Patient Global Assessment: 6 (on a scale of 0 to 10)
• Physician Global Assessment: 5 (on a scale of 0 to 10)

Now, using the formula:

CDAI = (Tender Joint Count) + (Swollen Joint Count) + (Patient Global Assessment) + (Physician Global Assessment)

CDAI = 5 + 4 + 6 + 5 = 20

In this case, the patient’s CDAI score is 20, indicating moderate disease activity. This suggests that the disease is not under control and may require further treatment adjustments.

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