Upper limb activity over time in complex regional pain syndrome type 1 as objectively measured with an upper limb-activity monitor: An explorative multiple case study

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DOI: 10.1016/j.ejpain.2005.01.005 · Source: PubMed
Abstract
An upper limb-activity monitor (ULAM) has been developed to determine activity limitations in complex regional pain syndrome type 1 (CRPS1). The ULAM is based on 24h ambulatory monitoring of body segment accelerations and enables valid and objective quantification of mobility and upper limb activity in transversal studies. To explore upper limb activity over time in acute upper limb CRPS1 as measured with the ULAM in a longitudinal study, and to compare this to time courses of other outcome measures for activity limitations and impairments. Four subjects were measured four times during a treatment protocol. Several ULAM outcome measures related to upper limb usage and mobility, three questionnaires (RASQ, DASH, RAND36), and six impairment outcome indicators (VAS-momentary pain, VAS-pain resulting from effort, volume, temperature, active range of motion, strength) were used. Objectively measured upper limb activity frequently improved; improvements of >5% were found for 63% of the ULAM outcome measures at final assessment. The ULAM outcome measures had a time course more similar to the body-part and CRPS1 specific questionnaire RASQ than the other questionnaires. The time course of impaired temperature was most often in accordance with the ULAM, and both VAS scores showed least accordance. Clear changes in upper limb activity over time were frequently found as objectively measured with the ULAM, and relationships among the time courses of the ULAM and other outcome measures were largely explainable. The ULAM can validly assess upper limb activity over time in CRPS1, but between-measurement variability needs careful consideration.
Upper limb activity over time in complex regional pain syndrome
type 1 as objectively measured with an upper limb-activity
monitor: An explorative multiple case study
Fabie
¨
nne C. Schasfoort
a,
*
, Johannes B.J. Bussmann
a
, H. John Krijnen
b
, Henk J. Stam
a
a
Department of Rehabilitation Medicine, Erasmus MC, University Medical Center Rotterdam, P.O. Box 1738, 3000DR Rotterdam, The Netherlands
b
Department of Anesthesiology, Pain Clinic, Ikazia Hospital, Rotterdam, The Netherlands
Received 31 August 2004; accepted 17 January 2005
Available online 26 February 2005
Abstract
Background: An upper limb-activity monitor (ULAM) has been developed to determine activity limitations in complex regional
pain syndrome type 1 (CRPS1). The ULAM is based on 24 h ambulatory monitoring of body segment accelerations and enables
valid and objective quantification of mobility and upper limb activity in transversal studies.
Aims: To explore upper limb activity over time in acute upper limb CRPS1 as measured with the ULAM in a longitudinal study,
and to compare this to time courses of other outcome measures for activity limitations and impairments.
Methods: Four subjects were measured four times during a treatment protocol. Several ULAM outcome measures related to upper
limb usage and mobility, three questionnaires (RASQ, DASH, RAND36), and six impairment outcome indicators (VAS-momen-
tary pain, VAS-pain resulting from effort, volume, temperature, active range of motion, strength) were used.
Results: Objectively measured upper limb activity frequently improved; improvements of >5% were found for 63% of the ULAM
outcome measures at final assessment. The ULAM outcome measures had a time course more similar to the body-part and CRPS1
specific questionnaire RASQ than the other questionnaires. The time course of impaired temperature was most often in accordance
with the ULAM, and both VAS scores showed least accordance.
Conclusions: Clear changes in upper limb activity over time were frequently found as objectively measured with the ULAM, and
relationships among the time courses of the ULAM and other outcome measures were largely explainable. The ULAM can validly
assess upper limb activity over time in CRPS1, but between-measurement variability needs careful consideration.
2005 Published by Elsevier Ltd on behalf of European Federation of Chapters of the International Association for the study of
Pain.
Keywords: Ambulatory accelerometry; Complex regional pain syndrome 1; Upper limb activity; Impairments; Activity limitations
1. Introduction
Complex regional pain syndrome type 1 (CRPS1)
encompasses various impairments (Atkins et al., 1989;
Schwartzman and Kerrigan, 1990) and usually leads to
limitations of everyday activities and functioning. Until
recently, most CRPS1 research concentrated on impair-
ments, and when activity limitations were quantified
merely scales and questionnaires were used (Schasfoort
et al., 2000). This lack of instruments to objectively mea-
sure activity limitations, together with the recently
stressed importance of objective outcome measures for
CRPS1 (Stanton-Hicks et al., 1998), and developments
in ambulatory accelerometry (Bussmann et al., 2001)
formed the basis of the upper limb-activity monitor
1090-3801/$32 2005 Published by Elsevier Ltd on behalf of European Federation of Chapters of the International Association for the study of
Pain.
doi:10.1016/j.ejpain.2005.01.005
*
Corresponding author. Tel.: +31 10 4087588; fax: +31 10 4633843.
E-mail address: f.schasfoort@erasmusmc.nl (F.C. Schasfoort).
www.EuropeanJournalPain.com
European Journal of Pain 10 (2006) 31–39
(ULAM). The device is based on long-term ambulatory
monitoring of signals from body-fixed acceleration sen-
sors and allows detailed objective quantification of
mobility-related activities and upper limb activity during
everyday life (Schasfoor t et al., 2002). The ULAM is an
extension of a validated activity monitor (AM) (Tulen
et al., 1997; Bussmann et al., 1998a,b,c; van den Berg-
Emons et al., 2000) and consists of sensors on forearms,
thighs and trunk, connected to a waist-worn recorder
(Fig. 1).
In chronic upper limb CRPS1 patients, the ULAM
detected limited intensity, percentage and proportion
of upper limb activity when compared to healthy sub-
jects (Schasfoort et al., 2003), impai red grip strength
and active range of mo tion of wrist and digits explained
most variability in activity limitations as measured with
the ULAM (Schasfoort et al., 2004), and a study of rela-
tionships between ULAM and questionnaires demon-
strated that the device offers an alternative but
important insight into everyday functioning (Schasfoort
et al., 2005). In short, the ULAM has proven feasibility,
validity and relevance in transversal group studies in
chronic upper limb CRPS1.
Usage of the ULAM has not yet been explore d longi-
tudinally on either the individual patient or the group
level, however. It is unknown whether the ULAM can
detect changes in upper limb activity over time, or
how changes as measured with the ULAM are related
to changes over time as measured with other instru-
ments (assuming that if functioning changes over time,
this is reflected in both ULAM and other instruments).
The ULAMs feasibility to detect changes is important
for CRPS1 research and practice because it enables
objective monitoring of treatment effects on everyday
functioning in future (intervention) studies. Therefore,
the research questions were:
What is the time course of upper limb activity as
objectively measured with the ULAM in acute upper
limb CRPS1?
Is the time course of upper limb activity as measured
with the ULAM related to the time courses of other
instruments and outcome measures at the activity
and impairment levels?
Which practical and methodological issues have to be
dealt with before the ULAM can be validly used in
future longitudinal (intervention) studies?
2. Materials and methods
2.1. Design, subjects and treatment regimen
Because changes are more likely in acute than in
chronic CRPS1, subjects having upper limb CRPS1
for less than 10 weeks were recruited from the pain clinic
(H.J.K.) for this explorative study. CRPS1 was diag-
nosed according to VeldmanÕs criteria (Veldman et al.,
1993) that are similar to those of the IASP (Stanton-
Hicks et al., 1995; Bruehl et al., 1999).
Four subjects with fractures as causative event volun-
teered. Subject A was a 48-year old man with non-dom-
inant side CRPS1 who worked with the police detective
force, was divorce d and lived with his two children. Sub-
ject B was a 5 8-year old man with non-dominant side
CRPS1, worke d as a mechanic, was married and lived
with his wife and child. Subject C was a 71-year old wo-
man wi th non-dominant side CRPS1, was married and
lived with husband. Subject D was a 52-year old man
with dominant side CRPS1, worked as a night watch-
man, was married and lived with his wife and two
children.
Since there still is no well-accepted evidence based
treatment algorithm for CRPS1 (Stanton-Hicks et al.,
1998; Goris, 2001; Ribbers and Stam, 2001), and treat-
ment efficacy to reduce impairments and/or activit y
limitations has scarcely been demonstrated with meth-
odologically sound studies (Perez et al., 2001; Oerlemans
Fig. 1. A subject wearing the ULAM in her home environment.
Several body-fixed piezo-resistive acceleration sensors (ADXL202, size
1 · 1 · 0.5 cm, Analog Devices, Breda, the Netherlands) are connected
to a waist-worn recorder (Temec Instruments BV, Kerkrade, The
Netherlands).
32 F.C. Schasfoort et al. / European Journal of Pain 10 (2006) 31–39
et al., 2000b; Schasfoort et al., 2000), we used a reason-
ably standardized treatment regimen that aimed at
improving impairments and everyday functioning.
Treatment parameters included radical scavenger vita-
min C, capillary vasodilator ketanserin, large vessel
vasodilator verapamil, aerobe metabolism stimulator
and radical scavenger carnitine, guanethinide iontof ore-
sis, carnitine infusion, physical therapy exercises and
connective tissue massage, and manual therapy with a
segmental approach aimed at improving functioning.
The subjects were assessed four times at roughly the
same points during their treatment, with at least two
weeks between measurements; t
0
within two days after
first visit to the pain clinic, t
1
just before a series of ion-
toforesis and infusion, t
2
just after a series of iontofo-
resis and infusion, and t
3
at least four weeks after t
2
.
Due to hospital logistics, however, subject D had two
series of iontoforesis and infusion between t
0
–t
1
and
t
2
–t
3
.
2.2. Instruments and outcome measures
The ULAM objectively determined whether or not
the upper limbs are active when a subject is performing
one of these mobility-related activities: lying, sitting,
standing, walking, cycling and general movement
(Schasfoort et al., 2002). The measurement technique
and automated signal analysis with ÔfeatureÕ signals de-
rived from raw acceleration signals ha ve been described
extensively (Bussmann et al., 1998a,b,c; van den Berg-
Emons et al., 2000, 2001a,b; Bussmann et al., 2001;
Schasfoort et al., 2002). The following ULAM outcome
measures, with lower scores indicating more limited
activity, were used (Schasfoort et al., 2003; Schasfoort
et al., 2004):
%dyn: the percentage of the measurement period that
dynamic mobility-related activities (i.e., the body
motions walking, cycling and general non-cyclic
activity) were performed;
intsit and intstand: the mean intensity of upper limb
activity of the involved side while subjects were sitting
and standing, expressed in scaled g (9.81 ms
2
);
%sit and %stand: the percentage of the time that the
involved uppe r limb was active while subjects were
sitting and standing.
Because there was no Ôgold standardÕ for objective
measurement of activity limitations over time and
changes were not guaranteed, the time courses of the
ULAM outcome measures were compared to the
courses of questionnaire outcome measures. We used
three questionnaires that also aim at limitations of
everyday functioning, but wi th other measuring tech-
niques and different operationalizations of the concept
functioning than the ULAM (Schasfoort et al., 2005).
It was assumed that if functioning changed over time,
this had to be reflected to a lesser or greater extent in
both ULAM and questionnaires, depending on the
strength of the conceptual relationships between the
instruments and similarities regarding instrument char-
acteristics. The following questio nnaires were used:
RAND36 health survey: the RAND36 (VanderZee et
al., 1996) is a generic questi onnaire that has been
used in CRPS1 research (Geertzen et al., 1998a,b).
Although, it was most responsive of five generic ques-
tionnaires (Beaton et al., 1997), it was less responsive
for upper limb disorders (Amadio et al., 1996)
because of ceiling- and floor-effects;
Radboud skills questionnaire: the Radboud skills
questionnaire (RASQ) is a reliable body-part specific
questionnaire (Oerlemans et al., 2000a) especially
developed for upper limb CRPS1 that compares the
current effort certain activities cost to pre-CRPS1
(Oerlemans et al., 2000b). Its responsiveness has not
been studied specifically;
Disabilities of arm shoulder and hand questionnaire:
the disabilities of arm shoulder and hand question-
naire (DASH) function and symptom score is a
30-item body-part specific questionnaire that mainly
measures limitations of everyday activity in upper
limb disorders (Hudak et al., 1996; Davi s et al.,
1999; Veehof et al., 2002) but also contains some
impairment items. Responsiveness was sufficient after
carpal tunnel release (Gay et al., 2003).
Time courses of six impairment outcome indicators,
that have been described as a responsive multi-compo-
nent score for (acute) upper limb CRPS1 (Oerlemans
et al., 1998; Oerlemans et al., 2000b), were also explored:
Vi sual analogue scale-effort: pain intensity resulting
from effort measured with a visual analogue scale
(VAS);
VAS-moment: momentary pain intensit y measured
with a VAS;
Volume: the difference in volumetric measurement s
(edema, atrophy) between both hands in relation to
the volume of the non-involved side measured with
a fluid overflow volumeter (Volumeters Unlimited,
Idywild, USA);
Temperature: temperature of the dorsal side of the
involved hand relative to the non-involved side mea-
sured with an infrared thermometer (Braun Pro 3000
Type 6014, Kronberg, Germany);
Active range of motion: maximum active range of
motion (AROM) within pain threshold of the wrist
and two most impaired fingers of the involved hand
relative to the non-involved side measured with a
goniometer;
F.C. Schasfoort et al. / European Journal of Pain 10 (2006) 31–39 33
Strength: four point grip strength of the involved
hand relative to the non-involved side measured
with a portable hand-held dynamometer (Microfet,
Hoggan Health Industries Inc., Draper, USA).
Impairment outcome indicator scores were converted
to a range of 1–10 with a sco re of 1 to be interpreted as
absence of that impairment and 10 as severely impaired.
For more information we refer to other studies (Oerle-
mans et al., 1998; Schasfoort et al., 2004).
2.3. Protocol
Assessments were in the subjectsÕ home environment.
Informed consent was signed, the ULAM was fitted and
information regarding treatment obtained. The subjects
were instructed to continue everyday activities while
wearing the ULAM for 24 h, except for swimming,
bathing or showering. After removal, the questionnaire
and impairment scores were obtained and subjects were
asked about ULAM wearing comfort and possible influ-
ences of wearing it on their behavior. Furthermore, we
asked whether the wearing period was representative
for other weekdays, and a gross overview of activities
performed was noted to support data interpretation.
The exact ULAM measurement technique and out put
parameters were not explained until final assessment.
All subjects agreed with this protocol, which was ap-
proved by the local medical ethical committees.
2.4. Data analysis
The absolute values of the ULAM outcome measures
were analyzed at assessments t
0
–t
3
to determine the time
course of objectively measured upper limb activity. Sub-
sequently, changes in the absolute values of all outcome
measures at t
1
,t
2
and t
3
compared to baseline (t
0
) were
normalized to visualize courses in time: the maximum
absolute change compared to baseline (either for time
interval t
1
–t
0
,t
2
–t
0
or t
3
–t
0
, either positive or negative,
either for subject A, B, C or D) was set at +100% (or
100% in case of a negative change).
These normalized change scores were shown in bar
graphs for both the individual subjects and the group
(n = 4). A from a clinical viewpoint Ôideal patternÕ for
time courses of an outcome measure would be that the
normalized time interval for t
3
–t
0
showed the highest
percentage, whereas the t
2
–t
0
and t
1
–t
0
intervals both
showed, respectively, lower percentages. Such a pattern
means that the more time had passed, the more a sub-
jectÕs functioning had improved (irrespective of whether
positive changes were due to treatment or natural
recovery).
These bar graphs displays differences between sub-
jects with respect to both magnitude and direction of
changes over time for each of the outcome measures
(because only one interval for one subject was set at
100%). It has to be noticed, however, that these bar
graphs only display differences between outcome mea-
sures with respect to direction of changes over time
and not magnitude (i.e., due to the normalization
method, the absolute value of the 100% normalized
change score of one outcome measure could theoreti-
cally be smaller than the absolut e value of a 10% nor-
malized change score of another outcome measure).
To compare time courses we calculated how often
changes over time between consecutive follow-up assess-
ments (t
1
–t
0
,t
2
–t
1
and t
3
–t
2
) as measured with the
ULAM were in the same direction as changes over time
as measured with the other outcome measures. For each
combination of two outcome measures twelve delta
pairs (4 assessments, so 3 deltas for each of the 4 sub-
jects) were analyzed. The higher the number of changes
in the same direction for two outcome measures (either
positive or negative), the more similar the time courses
for these outcome measures. This simple approach for
data analysis was in our opinion appropriate consider-
ing the relatively new ULAM measurement technique,
the low number of subjects, the explorative character
of the study, and the research questions.
3. Results
The subjects did not report any problems wearing the
ULAM although they had to get used to it for a few
minutes each time it was fitted. Five of the 12 measur e-
ment days were not representative according to the pa-
tientÕs own opinion (Table 1). This was due to unusual
overactivity such as organizing a barbeque party or unu-
sual inactivity such as going to a lecture, taking an unex-
pected day off from work, or hot humid weather.
3.1. Time course of objectively measured upper limb
activity
For subject A, all ULAM outcome measures demon-
strated improvements at the end of the 3-months mea-
surement period compared to baseline; intsit +24%,
%sit +28%, intstand +25%, %stand +7% (Table 1). At
final assessment, subject A was worki ng full-time and
started jogging again. Subject BÕs upper limb activity
as measured with the ULAM had hardly changed at
the end of his 3-month measurement period compared
to baseline (intsit +7%, %sit 2%, intstand +4%,
%stand +1%). It has to be noted that his treatment
was complicated with a delayed start and premature
ending of physical therapy in addition to an uninten-
tional too small initial dose of medication. For subject
C, each ULAM upper limb outcome measure indicated
improved functi oning between t
0
and t
1
, and was rela-
tively stable at t
2
and t
3
. At the end of the 4-month
34 F.C. Schasfoort et al. / European Journal of Pain 10 (2006) 31–39
period, all ULAM outcome measures indicated im-
proved functioning; intsit +158%, %sit +123%, intstand
+25%, %stand +2%. Subject DÕs upper limb activity
during sitting had hardly changed compared to baseline
(intsit +1%, %sit 4%), whereas the ULAM outcome
measures during standi ng indicated improved function-
ing despite unfavorable unrepresentativeness (intstand
+32%, %stand +9%). Improvements of >5% between
baseline and final assessments were found for the major-
ity of ULAM upper limb outcome measures (10/16,
63%) in these four subjects with acute upper limb
CRPS1.
3.2. Time courses of normalized change scores
The normalized change score patterns were Ôclinically
idealÕ only for few outcome measures (Fig. 2, see also
Section 2); actually primarily for the ULAM outcome
measure intstand, the RASQ, and the impairment out-
come indicator AROM. Questionnaires more often dis-
played a clinically ideal pattern than the ULAM that, in
turn, more often displayed such a pattern than the
impairment outcome indicators. Not one Ôclinically
idealÕ pattern was found for subject B; his normalized
change scores were divergent from the other subjects.
For subjects A, C and D, the majority of questionnaire
and impairment outcome measures displayed their max-
imum normalized positive change for the t
3
–t
0
time
interval, which was not true for the ULAM outcome
measures. Outcome measures that displayed a negative
normalized change or did not or hardly change during
two or more of the time intervals were mainly at the
impairment level, and mainly for subject B. The ULAM
outcome measure %dyn appeared dissimilar to the other
ULAM outcome measures.
3.3. Time courses of the ULAM outcome measures in
relation to other outcome measures
Calculations of how often changes over time between
consecutive assessments (t
1
–t
0
,t
2
–t
1
and t
3
–t
2
) were in
the same direction (Table 2) showed that the time
courses of ULAM outcome measures were most often
in the same direction with the RASQ. The time course
of the ULAM outcome measures intstand was overall
best related to the time courses of both the questionnaire
and impairment outcome measures (with a maximum
score of 12 changes in the same direction with the
RASQ).
4. Discussion
Despite actually unchanged functioning in sub ject B
and the sometimes very short (i.e., two weeks) time
intervals between assessments, objectively measured
improvements of >5% between baseline and final assess-
ments were found for the majority of ULAM uppe r limb
Table 1
Overview of absolute values for the ULAM outcome measures, the questionnaire outcome measures and the impairment outcome indicators of the
four individual subjects
Subject A Subject B Subject C Subject D
t
0
t
1
t
2
t
3
t
0
t
1
t
2
t
3
t
0
t
1
t
2
t
3
t
þ
0
t
1
t
2
t
3
ULAM activity outcome measures
The higher the score, the better the functioning
%dyn 9, 8 10, 1 11, 8 10, 6 11, 8 16, 6 10, 3 11, 8 7, 0 6, 8 7, 0 9, 4 19, 5 12, 3 17, 4 13, 8
intsit 2, 8 4, 0 4, 1 3, 5 3, 4 2, 8 3, 7 3, 6 1, 9 5, 1 5, 2 4, 9 2, 4 1, 9 2, 6 2, 4
%sit 27, 6 40, 4 35, 3 35, 2 37, 1 31, 0 39, 1 36, 4 20, 3 51, 4 45, 4 45, 1 23, 0 19, 5 26, 6 22, 2
intstand 6, 3 7, 1 7, 6 7, 9 8, 0 8, 3 9, 7 8, 3 9, 1 10, 7 11, 0 11, 3 6, 8 8, 4 8, 7 9, 0
%stand 53, 7 56, 1 55, 9 57, 4 73, 8 73, 6 78, 5 74, 7 79, 0 82, 4 77, 9 80, 2 68, 3 81, 9 76, 6 74, 4
Questionnaire activity outcome measures
The lower the score, the better the functioning
RASQ (1–5) 2, 5 1, 8 1, 3 1, 2 2, 8 2, 7 2, 3 2, 4 3, 8 2, 7 2, 3 2, 0 2, 9 2, 4 2, 1 1, 6
DASH (0–100) 41 44 24 15 42 39 50 41 67 56 50 50 57 50 41 34
The higher the score, the better the functioning
RAND36 (0–100) 62 68 71 79 61 51 59 61 33 40 56 49 69 65 62 70
Impairment indicator outcome measures
The lower the score, the better the functioning
VAS effort (1–10) 2 3 1 1 2 5 5 4 4 4 4 3 7 3 4 2
VAS moment (1–10) 1 1 1 1 1 2 5 4 3 2 3 3 2 2 2 1
Volume (1–10) 5 4 4 4 1 1 1 1 6 4 1 2 5 3 1 1
Temperature (1–10) 2 5 3 4 2 3 5 3 4 2 1 3 4 1 1 2
AROM (1–10) 7 7 6 5 3 2 2 2 8 6 6 5 6 3 2 2
Strength (1–10) 6 4 3 3 6 4 4 5 7 7 5 5 6 4 5 4
T
n
unrepresentative ÔinactiveÕ ULAM 24 h, T
þ
n
unrepresentative ÔoveractiveÕ 24 h ULAM.
F.C. Schasfoort et al. / European Journal of Pain 10 (2006) 31–39 35
outcome measures. Because we had no idea as to how
limited the subjects would be or how fast changes over
time would occur, the small time frames were considered
appropriate for the current longitudinal study, however.
The divergent time course of %dyn was anticipated con-
sidering the population studied; the subjects had an
upper limb disorder and were not limited with respect
to mobility. This was also found in chronic upper limb
CRPS1 (Schasfoort et al., 2003). The present 11–12
%dyn did not differ from healthy subjects (Bussmann
Subject A
-100
-80
-60
-40
-20
0
20
40
60
80
100
%dyn
intsit
%sit
intstand
%stand
RASQ
DASH
RAND36
VASeffort
VASmoment
volume
temperature
AROM
strength
normalized change scores
t1-t0
t2-t0
t3-t0
Subject B
-100
-80
-60
-40
-20
0
20
40
60
80
100
%dyn
intsit
%sit
intstand
%stand
RASQ
DASH
RAND36
VASeffort
VASmoment
volume
temperature
AROM
strength
normalized change scores
t1-t0
t2-t0
t3-t0
Subject C
-100
-80
-60
-40
-20
0
20
40
60
80
100
%dyn
intsit
%sit
intstand
%stand
RASQ
DASH
RAND36
VASeffort
VASmoment
volume
temperature
AROM
strength
normalized change scores
t1-t0
t2-t0
t3-t0
Subject D
-100
-80
-60
-40
-20
0
20
40
60
80
100
%dyn
intsit
%sit
intstand
%stand
RASQ
DASH
RAND36
VASeffort
VASmoment
volume
temperature
AROM
strength
normalized change scores
t1-t0
t2-t0
t3-t0
Group n=4
-100
-80
-60
-40
-20
0
20
40
60
80
100
%dyn
intsit
%sit
intstand
%stand
RASQ
DASH
RAND36
VASeffort
VASmoment
volume
temperature
AROM
strength
normalized change scores
t1-t0
t2-t0
t3-t0
Fig. 2. Overview of normalized change scores of all outcome measures for time intervals t
1
–t
0
,t
2
–t
0
and t
3
–t
0
, for the individual subjects and the
average score of these subjects as a small group. The maximum absolute change compared to baseline (either for time interval t
1
–t
0
,t
2
–t
0
or t
3
–t
0
,
either positive or negative, either for subject A, B, C or D) was set at +100% (or 100% in case of a negative change).
36 F.C. Schasfoort et al. / European Journal of Pain 10 (2006) 31–39
et al., 1998a,b,c; van den Berg-Emons et al., 2000,
2001a,b; Bussmann et al., 2001; Schasfoort et al.,
2003). Although, these four subjects showed more lim-
ited upper limb activity than 30 subjects with chronic
CRPS1 previously measured with the ULAM (Schas-
foort et al., 2003, 2004, 2005), this should not be inter-
preted as a confirmation of the supposition that
functioning is generally more limited in acute than in
chronic CRPS1. CRPS1 is a syndrome and varies enor-
mously between subjects with respect to type and mag-
nitude of impairments and activity limitations, as well
as the duration of these consequences.
The finding that the body-part specific RASQ had a
time course more similar to the ULAM than the
RAND36 and DASH was probably due to more simi-
larities with respect to operationalization of functioning
and other instrument characteristics, as also found in
our transversal studies in chronic CRPS1 (Schasfoort
et al., 2005). Changes over time measured with impair-
ment outcome indicators were less well related to
changes as measured with the ULAM than the question-
naires were. This was not surprising because impair-
ments are operationalizations of functioning at a
different level than ULAM an d questionnaires (i.e.,
body impairments versus a personÕs activity). Among
the impairments, the time courses of volume, tempera-
ture, AROM and strength were more frequently in con-
cert with the ULAM than the VAS pain scores, which
may be explained by widely varying pain levels during
the day in acute CRPS1 (Oerlemans et al., 1998). It
has to be noticed that the present VAS scores were not
high; the subjects may not have been representative for
acute CRPS1 with respect to pain intensity.
With respect to the third research question it ap-
peared that between-measurement variability is an
important methodological issue of ULAM measure-
ments. Variability between measurements can be result-
ing from several factors. First, everyoneÕs level of
everyday physical activity will vary, even within Ôregular
daysÕ, and thus the level of upper limb activity in CRPS
patients will also vary. The intra-individual biological
variability of upper limb activity as measured with the
ULAM could not yet be investigated because we have
only performed 24-h measurements. Between-day vari-
ability for %dyn has been studied in 48-h measurements
with the ULAMs older sibling AM (van den Berg-
Emons et al., 2001a,b), however, and appeared to be
1.1% and 1.3% in two different patient groups and
0.8% in healthy subjects. Some between-day variability
for ULAM data will not be problematic as long as it
is relatively small compared to actual changes. Intra-
and inter-individual between-day variability have to be
studied for both patients and healthy subjects to deter-
mine to which degree changed upper limb activity as
measured with the ULAM falls under biological vari-
ability and above which threshold changed upper limb
activity can be considered as clinically relevant. This is-
sue is important to de termine the optimal number of
monitoring days and the required sample size for future
studies, and is also related to anticipated treatment effi-
cacy and the time period between assessments in future
longitudinal studies. Of course, the current data do not
allow us to make statements on treatment efficacy.
Second, besides random fluctuation within a probably
limited range, some days may clearly be different from
ÔregularÕ days. This unrepresentati veness due to unusual
overactivity or inactivity was reflected in the ULAM
data. Because questionnaires measure a perceived aver-
age score over the last few days whereas the ULAM mea-
sured what subjects actually did during a specific 24-h
period, such unrepresentativeness was logically not (or
less) reflected in the questionnaire scores. Concerning
possible negative effects of unrepresentativeness of the
measurement day on validity, it will stay important to
ask a patient about this matter. Possibly, measurement
days that are not representative should not be included
in the analysis in future studies. Increasing the number
of measurement days will also address this issue.
Third, the instrument itself can be a source of within-
measurement variability. The ULAM upper limb out-
come measures are rather rough; it detects upper limb
activity but as a consequence of the measurement tech-
nique does not yet allow valid measur ement of every as-
pect of upper limb usage (Schasfoort et al., 2002). Due
to our experiences and data from previous studies, how-
ever, we think that this latter point is less important than
Table 2
The time courses of the five ULAM outcome measures in relation to the time courses of the questionnaire and impairment outcome measures
RAND 36 RASQ DASH Sum VAS effort VAS moment Volume Temperature AROM Strength Sum
%dyn 5 6 6 17 3 2 3 6 4 4 22
intsit 8 7 4 19 2 2 5 7 3 4 23
%sit 6 5 2 13 1 3 4 5 2 2 17
intstand 7 12 8 27 4 2 5 4 7 7 29
%stand 6 7 3 16 4 3 3 4 4 4 22
Sum 32 37 23 14 12 20 26 20 21
It was calculated how often changes over time between asessments (t
1
–t
0
,t
2
–t
1
and t
3
–t
2
) as measured with the ULAM outcome measure were in the
same direction as changes over time as measured with the other outcome measures (maximum per pair of outcome measures is 12).
F.C. Schasfoort et al. / European Journal of Pain 10 (2006) 31–39 37
the issue of between-day variability in everyday physical
activity.
In conclusion, clear changes in upper limb activity
over time were frequently found as objectively measured
with the ULAM. The relationships between the time
courses of the ULAM outcome measures and the time
courses of other outcome measures for activity limita-
tions and impairments appeared logical and for a great
deal explainable. These results, in our opinion, demon-
strate that the current ULAM has potential to objec-
tively and validly assess changes in upper limb activity
over time in future longitudinal (treatment efficacy)
studies in upper limb CRPS1. It has to be realized, how-
ever, that between-measurement variability in upper
limb activity is a factor that needs careful consideration
during data analysis, and especially during analyses at
the individual patient level.
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    • "These include psychological and social evaluation: Inventory for Social Support (ISS) [60], Pain Catastrophizing Scale Dutch Version (PCS-DV) [61– 63], RAND-36646566 , the Hospital Anxiety and Depression Scale (HADS) [67, 68] and the Tampa Scale for Kinesiophobia (TSK) [69, 70]. Physical activity: the Disabilities of Arm Shoulder and Hand Questionnaire (DASH) [42, 71, 72] when the upper extremity is affected, and the Walking Ability Questionnaire when the lower extremity is affected737475. Economic evaluations: The cost analysis is performed from a societal viewpoint in collaboration with the Institute for Medical Technology Assessment of Erasmus University Rotterdam. "
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    • "The controversy in the discrimination of a strong sympathetic reaction from CRPS has been discussed323334 44]. Feldman et al. in 1993 [41] defined the diagnosis of CRPS if four of the following five criteria are found: @BULLET inexplicable, diffuse pain @BULLET change of the skin complexion @BULLET diffuse oedema @BULLET abnormal skin temperature @BULLET limited activity of the affected extremity [2, 29, 30]. After a review of the literature, the diagnostic investigations for CRPS include laboratory exams [40] , conventional X-rays of the affected extremity, TG, MRI [31], ischaemia tests [7] and bone scans [14, 19, 20, 25, 37]. "
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    • "The device is based on ambulatory accelerometry and enables objective determination of activity in different postures (lying, sitting and standing) and motions (walking and general movement) during everyday functions . It is increasingly used in research involving a variety of patient groups, including acute [36] and chronic [37,38] CRPS patients. The signal analysis and output were described previously [34,35,39]. "
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