The validated composite disease activity score for psoriatic arthritis. A simple linear sum of five components: tender joint count (68 joints), swollen joint count (66 joints), patient pain VAS, patient global VAS, and serum CRP. Used as the primary endpoint in most recent PsA biologic trials.
Original Development
Schoels M, Alasti F, Smolen JS, Aletaha D
Ann Rheum Dis, 2016
1
Joint Counts (68 Tender / 66 Swollen)
Tender Joint Count (TJC)
/ 68
Swollen Joint Count (SJC)
/ 66
DAPSA uses 68-joint tender count and 66-joint swollen count (excluding hip joints from the swollen count). This is broader than the DAS28 count. Both peripheral and axial joints should be assessed, but the standard DAPSA joint count focuses on peripheral joints.
2
Patient Pain VAS
How would you describe your overall pain due to PsA? (Past week)
5
Patient rates arthritis-related pain on a 0-10 scale. 0 = No pain, 10 = Most severe pain imaginable.
0 (No pain)10 (Worst pain)
3
Patient Global Assessment
How active was your PsA overall? (Past week, patient global)
5
Patient rates overall disease activity. 0 = Not active, 10 = Very active.
0 (Not active)10 (Very active)
4
C-Reactive Protein (CRP)
CRP Value
mg/L
DAPSA uses CRP in mg/L. Enter the actual CRP value. If CRP is within the normal range or undetectable, enter 0.
📋 What This Calculator Does
DAPSA is a simple additive score designed specifically for psoriatic arthritis, combining five components without logarithmic transformations or complex weighting. DAPSA = TJC68 + SJC66 + patient pain VAS (0-10) + patient global VAS (0-10) + CRP (mg/L).
DAPSA has become the preferred composite disease activity measure in PsA trials because it is specific to PsA (unlike DAS28, which was developed for RA), is transparent and easy to audit, and has been endorsed by GRAPPA (Group for Research and Assessment of Psoriasis and PsA).
📊 Interpreting the Score
DAPSA Score
Activity State
Clinical Meaning
0 to 4
Remission
Treat-to-target goal. No meaningful articular disease activity.
4.1 to 14
Low Disease Activity
Acceptable alternative target. Low articular burden.
14.1 to 28
Moderate Activity
Consider therapy optimization. Most biologic eligibility criteria fall here.
> 28
High Activity
Active disease requiring escalation. Review DMARD adequacy.
DAPSA MCID: 3.5 points. Minimal clinically important improvement defined in the derivation cohort. Important limitation: DAPSA does not capture skin, enthesitis, dactylitis, or axial disease activity. It measures articular PsA activity only.
💡 Pearls and Pitfalls
✓
DAPSA is specific to articular PsA. Unlike DAS28 (developed for RA and adapted for PsA), DAPSA was designed from the ground up for PsA using a 68/66 joint count that better reflects PsA's articular distribution. Most recent Phase 3 PsA trials (including ixekizumab, secukinumab, and upadacitinib studies) have used DAPSA as a primary or major secondary endpoint.
✓
DAPSA remission ≤ 4 is stringent. The DAPSA remission threshold requires near-complete absence of tender and swollen joints, minimal patient-reported symptoms, and near-normal CRP. This is a high bar and roughly comparable to DAS28 remission in stringency.
⚠
DAPSA does not capture the full disease burden of PsA. DAPSA is an articular score only. It does not score skin (PASI), enthesitis, dactylitis, or axial disease. A patient with excellent DAPSA may still have significant active skin disease or enthesitis. Always assess the full PsA disease spectrum alongside DAPSA.
⚠
Use 68/66 joint count, not the 28-joint count. DAPSA was validated with TJC68 and SJC66. Substituting a 28-joint count produces a systematically lower and differently calibrated score. Some clinical settings use a modified cDAPSA (without CRP) or DAPSA with 28-joint counts, but these are not the validated standard.
🔬 Evidence
DAPSA was originally derived by Schoels and colleagues and was first described in the context of the SESAME (Simplified Psoriatic Arthritis Disease Activity Measure and Evaluation) project. The formal validation and cutoff establishment was published by Schoels, Alasti, Smolen, and Aletaha in Annals of the Rheumatic Diseases in 2016, using data from two PsA cohorts. Validation demonstrated strong discriminative ability and correlation with physician global assessment.
View References▾
1
Schoels MM, Alasti F, Smolen JS, Aletaha D.Evaluation of newly proposed remission cut-points for disease activity score in 28 joints (DAS28) in psoriatic arthritis and proposal of novel psoriatic arthritis-specific activity cut-points. Ann Rheum Dis. 2016;75(10):1811-1815.
2
Gossec L, Smolen JS, Ramiro S, et al.European League Against Rheumatism (EULAR) recommendations for the management of psoriatic arthritis with pharmacological therapies: 2015 update. Ann Rheum Dis. 2016;75(3):499-510. Endorses DAPSA.
For clinical decision support only. DAPSA measures articular disease activity only. Skin, enthesitis, dactylitis, and axial disease require separate assessment. Results should be interpreted by a qualified clinician in full clinical context.