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PRO in Axial SpA
Instruments currently available for the assessment of patients with axSpA focus
predominantly on specifi c aspects of health—such as pain, disease activity, and
physical function—and measure specifi c concepts such as physical function and
HRQoL. All measures were designed for use in AS, but they can also be used in
other SpA conditions according to the presence or absence of axial symptoms.
Single Measures for Assessing Symptoms (Pain, Stiffness, Fatigue)
In patients with axial involvement, the degree of both night pain and spinal pain during
the day is measured by using either a visual analogue scale (VAS) or a numerical rating
scale (NRS). In general, the use of an NRS is preferred by patients and doctors. Morning
stiffness in the spine is usually assessed for aspects, duration, and severity. In addition to
the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) result, a value over
4 on a pain scale from 0 to 10 is usually considered as refl ecting “active” disease. Pain
and stiffness have a considerable infl uence on HRQoL in AS patients. Overall, 83 % of
patients report problems related to pain, and for 1/3 of them this aspect is considered very
important [ 11 ]. Women are 2–3 times more likely to have high levels of pain than men.
Patients with AS report signifi cantly more back pain than patients with RA (44 vs. 25 mm
on VAS pain), while pain in peripheral joints is comparable in the two groups [ 12 ].
Fatigue has been described as a major issue in AS, with up to 65 % of the patients
reporting this symptom [ 13 ]. The scores on the fatigue question of the BASDAI have
been shown to be signifi cantly associated with scores on several dimensions of the
36-question Short Form Health Survey (SF-36) and with the AS-specifi c Quality of
Life (ASQoL) instrument, suggesting that HRQoL is infl uenced by the degree of fatigue
[ 14 ]. Fatigue is most often assessed by using item 1 of the disease-specifi c question-
naire for assessing disease activity in AS patients: the BASDAI (see next section).
The degree of fatigue has also been assessed in controlled trials by using the functional
assessment of chronic illness Therapy-Fatigue subscale (FACIT- fatigue) [ 15 ].
Disease Activity
BASDAI
BASDAI is a fully patient-reported measure. It is simple to use since it comprises
only six questions (see Appendix 1 ) [ 16 ]:
- Fatigue
- Axial involvement
- Peripheral articular involvement
U. Kiltz et al.