Patient_Reported_Outcome_Measures_in_Rheumatic_Diseases

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spectrum and, together with PsA, it is the best studied subtype so far. Patients with
pSpA who fulfi ll the classifi cation criteria for SpA but do not have psoriasis, IBD,
or a preceding infection are classifi ed as undifferentiated pSpA.
AxSpA can be classifi ed according to the Assessment of Spondyloarthritis
International Society (ASAS) classifi cation criteria [ 3 , 4 ]. Thus, patients with struc-
tural changes in conventional radiographs of the sacroiliac joints (classifi ed as
established AS) and patients who do not have such changes (classifi ed as non-
radiographic axSpA [nr-axSpA]) are covered by this concept, which is based on the
idea of a disease continuum. Nevertheless patients do show a similar disease burden
independent of a particular stage [ 5 ]. The disease spectrum of pSpA [ 4 ] is partly
overlapping with the concept of PsA, which also can be well classifi ed according to
the Classifi cation of Psoriatic Arthritis (CASPAR) criteria [ 6 ]. Patients with PsA
have peripheral arthritis, skin psoriasis, dactylitis, and enthesitis as predominant
features, but they also may have axial features and/or other extra-articular features
of SpA [ 6 ]. PsA is usually associated with skin psoriasis (sometimes also with nail
lesions), but those changes do not occur in all patients.
Patient reported outcomes (PROs) are at the core of assessing disease status and/or
treatment response with patient assessments of global health, pain, stiffness, physical
function, and decreased health-related quality of life (HRQoL). The majority of estab-
lished questionnaires used for axSpA have been developed based on evaluation of
patients with established AS. AS is the showcase of axSpA and has been known for
decades, but some PROs have also been tested in the whole group of axSpA patients.
For patients with PsA, some of the measures of the clinical domains have been suc-
cessfully adapted from measures used in the assessment of rheumatoid arthritis or AS
or even psoriasis. To capture all patient-perceived consequences of SpA across the
disease spectrum, major efforts have been made to develop valid and reliable question-
naires assessing PROs such as pain, stiffness, fatigue, and QoL in patients with SpA.
Here we review the PROs used for patients with SpA, separately for axSpA and
PsA. No validated instrument is currently available for patients with pSpA, but
some work has been done to establish such an instrument [ 7 ].
In the present chapter, we discuss the most widely used and/or best-validated
questionnaires including the psychometric information available for these question-
naires. Furthermore, we discuss the measures that are of relevance for clinical
practice. The selection of questionnaires was limited to those related to musculo-
skeletal manifestations. Thus, questionnaires focusing on gastrointestinal, cutaneous,
or eye manifestations are not reviewed in this chapter.

Table 5.1 The different
spondyloarthritis subtypes

Predominantly axial SpA Predominantly peripheral SpA

Non-radiographic SpA Psoriatic arthritis

Radiographic axial SpA

(Ankylosing Spondylitis)

Reactive arthritis

Arthritis associated with

infl ammatory bowel disease

Undifferentiated pSpA

SpA spondyloarthritis

U. Kiltz et al.