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aspects as pain, emotional functions, sleep, sexual functions, mobility, self-care,
and participation in the community life. The items can be summed up to give a total
score ranging from 0 to 17, with a lower score indicating a better and a higher score
indicating an inferior health status. Preliminary validity has been confi rmed in a
fi eld test in four English-speaking countries. The ASAS HI has been translated so
far into 15 languages and the psychometric properties of the ASAS HI and its trans-
lations are tested in a large ongoing trial worldwide [ 42 ]. It is important to empha-
size that the ASAS HI is a health index and not a HRQoL instrument. Health is
thereby operationalized through the ICF concept of functioning. With the ASAS HI,
the occurrence of problems is captured in different categories of functioning and are
not depending on the subjective experience of the patients, which is a prerequisite
of a HRQoL instrument.
Psoriatic Arthritis
Clinical Picture of PsA
Psoriatic arthritis (PsA) is a heterogeneous disease, which includes varying levels of
peripheral joint involvement and skin manifestations. Musculoskeletal involvement is
characterized by synovitis, enthesitis, dactylitis, and spondylitis. The manifestation
can present as an asymmetric oligoarthritis, a polyarthritis as an axial manifestation
[ 43 ]. Therefore, the key clinical features of PsA that should be assessed in order to
determine disease severity and effect of treatment include peripheral arthritis, skin and
nail psoriasis, axial disease, enthesitis, and dactylitis. The impact of PsA is wide-reach-
ing, and both physical and mental aspects of quality of life can be modifi ed by this
disease. Thus, the measurement of the patient’s status rests in part on the assessment of
patient reported outcomes, i.e., questionnaires to assess different aspects of life.
Here, we will review different patient-reported questionnaires that are either
specifi c to PsA, or generic, and which are used to assess people with PsA.
Assessment of Patients with PsA
The Core Set : Several years ago, the international group Outcome Measures in
Rheumatology (OMERACT) and the Group for Research and Assessment of
Psoriasis and Psoriatic Arthritis (GRAPPA) decided through consensus on a Core
Set of variables to be collected in clinical trials of PsA [ 44 ]. These experts have
proposed six core domains ( inner circle ) to be measured in clinical trials and obser-
vational studies of PsA: peripheral joint activity, skin activity, pain, patient global
assessment (PGA), physical function, and HRQoL (Fig. 5.1 ) [ 44 ]. The “outer circle”
corresponds to domains that are not necessary to assess in PsA trials or domains that
are still under evaluation.
U. Kiltz et al.