Physiological Profile Assessment (PPA)
The Physiological Profile Assessment (PPA) is used by the Physiotherapist in the Falls Clinic to determine possible causes of postural instability and falls. The PPA QuickScreen© is also available for use by therapists within the community.
Targeted interventions are known to be more effective in reducing falls. The PPA involves measurement of risk factors which allows for specific recommendations to be made. It can be carried out at the same time as the physiotherapy specialist assessment and negates the need to perform lower limb strength testing, lower limb sensation (proprioception/sensation/reflexes), and clinical balance measures (Berg/TUSS/180º turn).
Criteria to prompt completion of a PPA
- One or more falls and a Timed Up and Go of 15 seconds or over.
PPA conceptual model
- Physiological, rather than disease-oriented
- Involves direct assessment of sensorimotor abilities
- Assumes that disease processes will manifest in impaired performances in one or more tests.
FallScreen© is a falls risk calculator and has two forms: a short form and a long form. The short form is designed as a screening instrument suitable for General Practice surgeries, acute hospitals, and long-term care institutions, and is used within the Falls Clinics of Lambeth and Southwark. It takes only 15 minutes to administer and contains five items: a single assessment of vision, peripheral sensation, lower limb strength, reaction time and body sway.
The PPA was developed by Dr Stephen Lord at the Prince of Wales Medical Research Institute in Sydney, Australia. For more information, please visit his website at: www.powmri.edu.au/fbrg/
The physiological assessments
- Visual function is measured using a dual contrast visual acuity chart, the "Melbourne Edge Test", and a device for measuring depth perception
- Lower limb sensation is assessed with tests of proprioception, touch sensitivity and vibration sense
- The strength of three muscle groups in both legs is measured: the knee flexors and extensors and ankle dorsiflexors
- Simple reaction time is assessed using movement of the finger as the response, and choice reaction time is assessed using a step as the response
- Body sway on a firm and compliant (foam rubber) surface with eyes open is assessed using a swaymeter that measures displacements of the body at the level of the waist.
These assessments are simple, "low-tech", and readily accepted by older subjects. All have high external validity and test-retest reliability and are described in detail in our published papers (1-7). When combined in multivariate discriminant analyses, we have found that these tests can predict those at risk of falling with 75% accuracy in both community and institutional settings.
Short form tests
Edge contrast sensitivity is assessed using the Melbourne Edge Test. This test presents 20 circular patches containing edges with reducing contrast. Correct identification of the orientation of the edges on the patches provides a measure of contrast sensitivity in decibel units, where dB=-10log10 contrast.
Proprioception is assessed by asking seated subjects with eyes closed to align the lower limbs on either side a 60cm by 60cm by 1cm thick clear acrylic sheet inscribed with a protractor. Any difference in matching the great toes is measured in degrees.
Lower limb strength
The strength of three leg muscle groups (knee flexors and extensors and ankle dorsiflexors) is measured while subjects are seated. In each test, there are three trials and the greatest force is recorded.
Reaction time is assessed using a light as the stimulus and depression of a switch (by either the finger or the foot) as the response. Reaction time is measured in milliseconds.
Sway is measured using a swaymeter that measures displacements of the body at waist level. The device consists of a 40cm long rod with a vertically mounted pen at its end. The rod is attached to subjects by a firm belt and extends posteriorly. As subjects attempt to stand as still as possible, the pen records the sway of subjects on a sheet of millimetre graph paper fastened to the top of an adjustable height table. Testing is performed with the eyes open and closed on a piece of medium density foam rubber (15 cm thick). Total sway (number of square millimetre squares traversed by the pen) in the 30 second periods is recorded for the four tests.