das28 calculator

What is DAS28?

DAS28 stands for Disease Activity Score using 28 joints. It is one of the most widely used tools for assessing disease activity in rheumatoid arthritis (RA). Clinicians use it to monitor response to treatment, support treat-to-target strategies, and decide whether to continue, intensify, or modify therapy.

The score combines four dimensions into one number:

• Tender joint count out of 28 joints (TJC28)
• Swollen joint count out of 28 joints (SJC28)
• A laboratory inflammation marker (ESR or CRP)
• Patient global assessment of health (usually 0-100 mm visual analog scale)

How to interpret DAS28 results

After calculating, classify disease activity using these conventional cutoffs:

• Remission: < 2.6
• Low disease activity: 2.6 to 3.2
• Moderate disease activity: > 3.2 to 5.1
• High disease activity: > 5.1

In many treatment plans, the goal is remission or at least low disease activity. Repeated scores over time are often more useful than a single isolated value.

Input guide for this calculator

1) Tender Joint Count (TJC28)

Count joints that are painful on pressure or movement among the standard 28-joint set. Valid range in this calculator is 0 to 28.

2) Swollen Joint Count (SJC28)

Count joints with objective swelling among the same 28 joints. This should also be entered as a value from 0 to 28.

3) ESR or CRP

Select your preferred method:

• DAS28-ESR: enter ESR in mm/hour (must be greater than 0 for logarithmic calculation).
• DAS28-CRP: enter CRP in mg/L (0 or greater).

These methods are related but not perfectly interchangeable. For longitudinal follow-up, stick to one method consistently when possible.

4) Global Health (GH) / Patient Global Assessment

Enter a patient-reported score from 0 to 100 mm, where higher values indicate worse perceived health or disease impact.

Why DAS28 matters in rheumatoid arthritis management

Modern RA care emphasizes objective monitoring. DAS28 helps bridge clinical examination, laboratory data, and patient experience. It is frequently used in outpatient rheumatology clinics, research studies, and quality improvement programs.

Common uses include:

• Baseline disease activity assessment at diagnosis or treatment initiation
• Follow-up monitoring every few weeks to months
• Evaluating effectiveness of DMARDs and biologic agents
• Documenting eligibility or response criteria in certain protocols

Practical example

Suppose a patient has TJC28 = 8, SJC28 = 6, ESR = 30 mm/h, and GH = 55. The DAS28-ESR result will generally fall in the moderate activity range. If repeated after treatment escalation and the score drops near 3.0, that suggests a meaningful improvement toward low disease activity.

Limitations to keep in mind

• DAS28 evaluates only 28 joints and may miss activity in feet/ankles in some patients.
• Inflammatory markers can be influenced by non-RA conditions (infection, age, comorbid inflammation).
• Patient global assessment can be affected by fibromyalgia, mood, or chronic pain independent of synovitis.
• No calculator replaces full clinical evaluation by a qualified professional.