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Delve into the significance of PsA outcome measures

Measuring disease activity: Composite vs individual domain measures

Disease outcome measures in PsA

Assessment of patients with PsA requires consideration of all disease domains, as well as the impact on pain, function, quality of life, and structural damage. Comorbidities and related conditions should be considered for their impact on management approaches.1

Several different measures of disease activity in PsA have been developed, including composite and domain-specific assessments2-4:

  • Routine use of disease activity measures in clinical practice needs to be implemented to help more patients achieve personalized disease outcome goals1,3
  • ~90% of clinicians agree that there is a need for a continuous composite measure for routine practice3

Composite disease outcome measures

Composite measures allow for the estimation of overall disease activity and disease burden across several disease domains and often include factors that are important to both clinicians and patients3,5:

  • Domain severity (arthritis, enthesitis, dactylitis, axial disease, and psoriasis)
  • Patient assessments of pain and fatigue
  • Physical functioning assessments
  • Health-related quality of life scores

Many different composite outcome measures are available, and their use in clinical practice often depends on clinician and patient preference, time available, and ease of use.2

Routine use of DAPSA and the MDA index is recommended by GRAPPA and OMERACT, and PsAID-12 (a patient-reported measure) is commonly used in clinical practice to understand the impact of PsA from the patient perspective.5,6,*

*Examples of commonly used disease measures and not an exhaustive list of all available measures.

Disease Activity Index for Psoriatic Arthritis (DAPSA)

DAPSA is a GRAPPA and OMERACT guideline–recommended, validated composite measure that consists of five items: SJC66, TJC68, PtGA VAS, patient pain VAS, CRP.6-8,*

*If CRP is not included, it is called the clinical or cDAPSA (4 items).2

Considerations
  • Quick and easy to administer and calculate during the clinic visit2
  • Can measure both current disease activity and treatment response2
  • Useful to assess polyarticular peripheral arthritis2

CRP=C-reactive protein; PtGA=patient global assessment; SJC=swollen joint count; TJC=tender joint count; VAS=visual analog scale.

Minimal Disease Activity (MDA) Index

MDA index is a GRAPPA and OMERACT guideline–recommended, validated composite measure that consists of seven items: SJC66, TJC68, patient global assessment (PtGA) VAS, patient pain VAS, enthesitis, function (HAQ), skin (PASI or BSA).6,9,10

Considerations
  • Simple and easy to administer; paper or electronic applications available2,6
  • MDA (and VLDA) criteria are useful measures of good disease control; a continuous measure of disease activity2
  • Valid in polyarticular and oligoarticular disease2

BSA=body surface area; HAQ=Health Assessment Questionnaire; PASI=Psoriasis Area Severity Index; PtGA=patient global assessment; SJC=swollen joint count; TJC=tender joint count; VLDA=very low disease activity.

Psoriatic Arthritis Impact of Disease (PsAID)-12

PsAID-12 is a composite measure to specifically assess the impact of PsA from the patient’s perspective.11 It includes 12 physical and psychological domains: pain, fatigue, skin, work and/or leisure activities, function, discomfort, sleep, coping, anxiety, embarrassment, social life, and depression, all assessed by patients on NRS.11

Considerations
  • The 12-item scale was developed for clinical practice; it is a quick, self-administered questionnaire on paper or electronic format available from EULAR2
  • Correlates well with MDA/VLDA6,11,12

EULAR=European Alliance of Associations for Rheumatology; MDA=minimal disease activity; NRS=numerical rating scale; VLDA=very low disease activity.

Additional disease outcome measures in PsA

PsA is a highly heterogeneous disease and, as a result, a large array of disease outcome measures have been developed and validated to define and monitor it.2,14 These include physician- and patient-administered measures, composite and single-domain measures for each of the disease domains, and measures for quality of life and ability to carry out activities of daily living.2,14 In addition to those measures summarized above, other commonly used measures are included (but are not limited to) those listed in this link. View additional measures.

Individual domain-specific disease outcome measures

Use of individual domain-specific measures allows for accurate assessment of disease activity in each domain3

  • These measures can be useful to supplement composite measures, particularly where one or two disease manifestations present with severe symptoms, and a composite measure may “dilute” the impact seen in individual domains3
  • They can provide an assessment of often overlooked symptoms, such as fatigue, which can have an important impact on a patient’s life13

Many domain-specific measures have been developed and their use in clinical practice depends on several factors, such as individual patient needs, time available, and ease of use.2

For example, there are specific measures available for nail psoriasis (NAPSI), dactylitis (LDI), enthesitis (LEI and the SPARCC index), and psoriasis (PASI).14,*

*Examples of commonly used disease measures and not an exhaustive list of all available measures.

Nail Psoriasis Severity Index (NAPSI)

NAPSI is a tool to assess severity of nail psoriasis on the nail bed and nail matrix.14 Evaluations include: onycholysis; splinter hemorrhages; hyperkeratosis; oil-drop dyschromia (for nail bed); and pitting, leukonychia, crumbling, and red spots in the lunula (for nail matrix).14

Considerations
  • A simple, numeric, reproducible, objective tool14
  • A shorter, modified version, mNAPSI, is available14,15
  • Evidence of nail psoriasis can be a surrogate marker for DIP arthritis16

DIP=distal interphalangeal.

Leeds Dactylitis Index (LDI)

LDI measures the severity of dactylitis by assessing the circumference of swollen digits at the base of the finger and tenderness of affected fingers (and toes).14

Considerations
  • Total administration takes <10 minutes, with no discomfort to the patient14

Leeds Enthesitis Index (LEI)

LEI measures the presence or absence of tenderness in 6 entheseal sites, developed specifically for use in PsA.14

Considerations
  • Takes ~30 seconds to complete, with minimal burden to the patient14
  • Routine assessments of entheses with LEI can define enthesitis, a key indicator of disease activity in patients with PsA18

Spondyloarthritis Research Consortium of Canada (SPARCC)

SPARCC measures the presence or absence of tenderness in 16 entheseal sites.14

Considerations
  • Takes ~2–5 minutes to complete, with minimal burden to the patient14
  • Routine assessments of entheses with SPARCC can define enthesitis, a key indicator of disease activity in patients with PsA18

Psoriasis Area and Severity Index (PASI)

PASI assesses psoriasis lesion burden based on BSA involvement and degree of severity of erythema, induration, and desquamation, for 4 body areas (head, upper and lower extremities, and trunk).14

Considerations
  • Not typically used in patients with <3% BSA lesional involvement14
  • BSA calculators can be used for scoring14
  • Can be performed adequately by trained rheumatologists14
  • Extensively studied and validated measure of psoriasis severity2,14

BSA=body surface area

Additional disease outcome measures in PsA

PsA is a highly heterogeneous disease and, as a result, a large array of disease outcome measures have been developed and validated to define and monitor it.2,14 These include physician- and patient-administered measures, composite and single-domain measures for each of the disease domains, and measures for quality of life and ability to carry out activities of daily living.2,14 In addition to those measures summarized above, other commonly used measures are included (but are not limited to) those listed in this link. View additional measures.

Where do we go from here?

Routine implementation of more stringent measures of PsA disease activity is needed to bring clarity to the complexity of PsA disease management and to help raise the bar in helping more patients achieve optimal disease outcome goals.6,20

How may a deeper understanding of cytokines help with assessing disease activity?

Understanding the pathologic processes leading to PsA is important to understanding its heterogeneous nature.

Gaze upon the Gallery of Cytokines

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