The research
team identified that no gold standard was available for measuring
disease activity in AS. The authors acknowledged research, from the
Royal National Hospital for the Rheumatic diseases, that identified
fatigue as a major component of AS. It was therefore suggested that
this should be incorporated into measures of disease activity. The
BASDAI was subsequently developed. As with the functional index, the
research team included major input from patients with AS, to enhance
clinical relevance and disease specifity.
Like
the BASFI, the BASDAI consists of 10cm visual analog scales used to
answer 6 questions pertaining to the 5 major symptoms of AS:
-
Fatigue
- Spinal pain
- Joint pain / swelling
- Areas of localized tenderness
- Morning stiffness.
To give
each symptom equal weighting, the mean of the two scores relating
to morning stiffness is taken. The resulting 0 to 50 score is divided
by 5 to give a final 0 – 10 BASDAI score (refer
to page).
When
clinically tested, results showed:
- 1)
BASDAI to be a quick and simple index (taking between 30 secs and
2 mins to complete)
- BASDAI
demonstrated statistically significant (p<0.001) reliability.
- The
individual symptoms and the index as a whole demonstrated good score
distribution, using 95% of the scale.
-
Following a 3 week physiotherapy course, the BASDAI showed a significant
(p=0.009) 16.4% score improvement, therefore demonstrating a sensitivity
to change.
(Garrett et al, 1994)
By
comparison, a previous disease activity index did demonstrate greater
sensitivity to change (22.8% improvement being shown) (Garrett et
al, 1994). However, the authors recognised that the previous index
had a bias towards pain and included a scale measuring patient’s
sense of well being. It is felt that the BASDAI is superior in terms
of symptoms considered and their weighting. This may be due to the
input from patients with AS when the index was developed. The BASDAI
was also found to be superior in all aspects to the Newcastle Enthesis
index (Garrett et al, 1994).
Calin
et al (1999) have further assessed the validity of the BASDAI. With
a sample size of 473, a double-blind, placebo-controlled study of
6 weeks duration was conducted. Subjects were divided into two groups.
One group received a placebo. The other group received an active
NSAID. Disease activity was assessed with the BASDAI and by analysing
a wide range of individual symptom components. The authors concluded
that BASDAI has excellent content validity.
The
BASFI and BASDAI have also been translated into Swedish for use
in Sweden. Cronstedt et al (1999) and Waldner et al (1999) have
assessed the Swedish version of these two indices. In agreement
with the studies at Bath, the Swedish versions of the BASFI and
BASDAI proved to be reliable, valid, and sensitive to change following
a course of inpatient therapy.
To
conclude, the BASDAI is user friendly, highly reliable, reflects
the entire spectrum of the disease, and is sensitive to clinical
changes (Garrett et al, 1994).
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