Transcript The Leeds Dactylitis Index An objective outcome measure

The Reliability of Pressurestat for Measuring Plantar Foot Pressures in Rheumatoid Arthritis
Jill Firth1, Philip Helliwell2, Debbie Turner3, Wendy Smith3 and James Woodburn4
1Academic Unit of Musculoskeletal Nursing, University of Leeds, 2Academic Unit of Musculoskeletal Disease, University of Leeds, 3Department of Podiatry, University of Huddersfield,4 HealthQWest, Glasgow Caledonian University , UK
1 Background
3 Methods
• Plantar pressure measurements have been used to
measure foot function and as a screening tool to establish
risk for tissue injury in the 'at risk' foot.
• 10 RA patients were recruited. Simultaneous barefoot
plantar pressure measurements were recorded from the
PressurestatTM footprint mat (Footlogic, Inc, New York,
USA) and the EMED-ST (Novel, GmbH, Munich,
Germany) systems using a first-step approach.
• One disadvantage of plantar pressure measurements is
that they are often dependent on costly specialist
equipment and therefore data collection is often limited to
specific sites.
• PressurestatTM is a semi-quantitative foot pressure
measurement system that is relatively cheap and easy to
use and therefore has the potential to be used in routine
clinical practice.
• Some reliability work has been undertaken in the area of
the identification of high plantar pressures in the diabetic
foot, but the reliability of this pressure measurement
system in the rheumatoid foot has not been established.
Table 1 Inter-observer kappa values at 1st and 2nd reading
Observer 1
Observer 2
Observer 3
Observer 4
0.45 / 0.59
0.26 / 0.38
0.37 / 0.49
0.27 / 0.30
0.43 / 0.47
Observer 2
• The foot was divided into six regions for analysis: distal
medial and lateral, middle medial and lateral and proximal
medial and lateral.
Observer 4
• Four independent examiners quantified the peak
pressure in each of the regions on the PressurestatTM
using the calibration card provided on two separate
occasions at least one week apart.
Figure 2 – Background Noise
0.38 / 0.21
• The absolute peak pressure values in each mask region
were determined from the EMED-ST platform by masking
in the same manner using a real size plantar pressure
printout.
2 Aims
• To establish the inter and intra–rater reliability of
PressurestatTM to measure plantar foot pressures in
patients with rheumatoid arthritis (RA).
Figure 1 – PressurestatTM
4 Results
• The raw PressurestatTM readings consistently exceeded
those obtained by the EMED-ST system, whether the
average (the mean of the range given by PressurestatTM)
or maximum values were used (median differences
266kPa and 370 kPa for mean and maximum readings).
• Correcting the PressurestatTM scores for 'background
noise' (not suggested by manufacturer) inverted and
improved these figures (median differences: -100kPa and
-55kPa for mean and maximum).
• Inter-observer kappa values are given in the Table (first
and second readings). This represents fair to moderate
agreement, with the level of improvement improving with
the second readings.
• Intra-observer kappa values were 0.57, 0.51, 0.33 and
0.43 for observers 1-4 respectively. This represents fair
to moderate intra-observer agreement.
• Agreement varied by region assessed. For the forefoot
observers had 62% complete agreement, for the mid-foot
45%, and the rearfoot 51%.
5 Conclusions
• Pressure data obtained with the Pressurestat TM system in patients
with rheumatoid arthritis is imprecise.
• This study has shown fair to moderate intra- and inter- observer
agreement when reading the PressurestatTM prints, with some
evidence of a learning effect.
Acknowledgements
Jill Firth is funded by a Smith & Nephew Foundation Doctoral
Scholarship