radiological outcome in ankylosing spondylitis - Rheumatology

374 BRITISH JOURNAL OF RHEUMATOLOGY VOL. 35 NO. 4
FIG. 1.—Radiographic scoring system (see the text for details).
performed in the previous 12 months. All corners of
each vertebra between the lower border of T12 and the
upper border of SI are examined and scored 1 for
erosion, squaring or sclerosis, 2 for syndesmophyte
formation, and 3 for total bony bridging, giving a
maximum possible score of 72 (see Fig. 1). In ~ 10%
of films, the upper sacrum is poorly shown on the
lateral lumbar spine view and a lateral sacral film is
needed in order not to compromise the analysis.
Following a period of training, the available X-rays
from the original study and all the latest X-rays were
scored independently by a rheumatologjst and a
radiologist, but for the purpose of this study we
subsequently examined each X-ray jointly to agree on
the final score. The effective radiation dose of a lateral
lumbar spine X-ray taken at 80 kVp is 0.205 mSv.
Forty-two patients had had quantitative sacroiliac
scintigraphy using 450 mBq Tc-99m-labelled methylose
diphosphonate (MDP) in a previous study to assess the
role of isotope scanning in the management of AS [11].
Ratios were calculated, including sacroiliac: soft tissue
(SIJ:ST) and sacrum:ST.
Statistical analyses were performed with the Number
Cruncher Statistical System 5.01. Spearman's cor-
relation was used to investigate the relationship of
SASSS with other variables.
RESULTS
We have defined initial results as time (t) = 0 and the
latest results as t = 1.
Five patients failed to attend the whole study and
three more were reclassified as diffuse idiopathic
skeletal hyperostosis, so 53 patients with definite AS
were fully assessed. The median age of patients at
follow-up was 47.5 yr (range 32-66) and the median
duration of history was 20 yr (range 9-48). The median
study follow-up time was 9 yr.
Thirty-two patients had definite syndesmophytes and
21 had no sign of syndesmophytes.
Change in SASSS over time
The median total spine score at / = 0 was 5.5 (range
0-52); 9 yr later the median score was 28.5 (range 0-72)
(P < 0.0001).
Figure 2 shows the interindividual variation in
change in spine score, and in particular shows that
while in some patients there is little change, others
show considerable progression of radiological changes
during the study period. By choosing an arbitrary value
of 12 to separate the patients into slow and fast
progressors, we were unable to demonstrate any
variable that could predict outcome.
Change in spine score was not significantly related to
clinic attendance, length of history, age of patient or
age at diagnosis.
Relationship between SASSS and clinical measurements
SASSS was significantly correlated with chest
expansion, occiput-wall distance, finger-floor distance,
72 -
TIME
FK}. 2.—Change in Stoke AS Spine Score in patients with AS
over 9 yr.
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