Problem elicitation to assess patient priorities in ankylosing spondylitis & fibromyalgia (FM)

OBJECTIVE. To elicit patient priorities as outcome measures in
ankylosing spondylitis (AS) and fibromyalgia (FM); to relate
these measures to other outcomes; to assess construct validity
and sensitivity to change of the problem elicitation technique
(PET) questionnaire.

METHODS. One hundred thirty-four patients
with AS were randomly allocated to weekly sessions of group
physical therapy or daily exercises at home, whereas 73
patients with FM were randomized into one of 3 groups (low
impact fitness, biofeedback, controls). The PET questionnaire
was applied by trained interviewers at baseline and at 6 (FM)
and 9 (AS) month followup. A PET score was calculated at each
assessment. Construct validity of the PET was assessed by
correlation and multiple regression of baseline values with
other disease outcomes (pain, stiffness, patient's global
assessment, Sickness Impact Profile (SIP), Health Assessment
Questionnaire (HAQ), Arthritis Impact Measurement Scale
(AIMS), patient utilities). Sensitivity to change of PET was
assessed against changes in these outcomes and by comparing
the efficiency of the PET with other outcomes.

Patients with FM identified more problems (mean 6.8) than
patients with AS (mean 4.4). Moreover, more patients with AS
than with FM were unable to identify any problem at baseline
(10% compared to 1%). The PET score improved from 14.9 to 11.3
(p = 0.0001) in patients with AS but did not change from 21.8
to 21.1 (p = 0.24) in patients with FM. Construct validity
testing of the PET score showed statistically significant (p <
0.05) correlations with AIMS, utilities, SIP, HAQ, pain,
stiffness, and patient's global health in both groups of
patients (r varying from 0.22 to 0.66). By multiple regression
pain explained 29% of the variance in PET scores among
patients with AS. In FM patient global assessment accounted
for 39% of total variance of PET scores, whereas pain
explained another 15%. Changes in PET scores correlated
significantly (p < 0.05) with changes in AIMS, utilities,
pain, stiffness, and patient global health in both AS and FM
(r varying from 0.22 to 0.51). Some 6% of the variance in
changes in PET scores was explained by changes in pain in
patients with AS and 35% by changes in pain and subjective
health in patients with FM. Assessment of sensitivity to
change revealed that efficiency of the PET score was 0.6 in
patients with AS and 0.09 in those with FM. Compared to other
outcomes this was reasonable in patients with AS but low in
those with FM.

CONCLUSION. Obtaining patient priorities was
generally feasible. In both groups of patients construct
validity of the PET questionnaire was satisfactory. The PET
was much more sensitive to change in patients with AS than in
patients with FM.

Bakker C, van der Linden S, van Santen-Hoeufft M, Bolwijn P, Hidding

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