The purpose of this paper and instructional session is to provide a brief review of the levels of evidence, briefly review the current state of evidence in the field of wheelchair seating and mobility, present methods for locating evidence and assessing the level of the evidence. The majority of the session will demonstrate how this evidence can be used to strengthen a practitioner’s request to third party payers for funding.

Evidence based practice has fully emerged in all fields of healthcare including rehabilitation. It is the responsibility of all practitioners to be knowledgeable of evidence, be able to assess the level and quality of evidence, and appropriately apply evidence in their daily practices (Holm, 2000).

Evidence has been classified in a hierarchy (Gray, 1997; Holm, 2000; Moore et al., 1995). These levels can be summarized as follows:

• Level I - systematic reviews or meta-analysis of well-designed studies
• Level II – one or more well-designed study using randomization
• Level III – a well designed study but without randomization
• Level IV – well designed non-experimental study from more than one facility or research group
• Level V - subjective opinions of well known respected authorities based on clinical experience, case studies, or expert committee reports (also known as expert opinions)

There have only been one or two attempts at critically and systematically reviewing the research associated with wheelchair seating and mobility. Reid (2000) presented a work in progress critical analysis of research related to seating in the adult population. No findings were discussed however an outline for a methodology for the systematic analysis was presented. Roxborough (1995) conducted a systematic review of the efficacy and effectiveness of adaptive seating for children with cerebral palsy and found that additional research related to seating is needed to further demonstrate the outcome of these interventions.

One party’s case and evidence should be "more convincing" than the other side as well as meeting necessary legal burdens of proof. Most funding sources also offer procedures for appealing denials that follow proceedings similar to and including court procedures.

The purpose of this paper and presentation is not to provide detailed information on how to critique research or assess the quality of evidence but rather to provide strategies in using evidence to justify the interventions. There are several resources available on Evidence Based Practice one can refer to (Gray, 1997; Holm, 2000; Moore et al., 1995; Sacket et al., 1997). The Journal of the American Medical Association also has a series on using the literature, which is worth reading (Barratt et al., 1999; Guyatt et al., 1993; Guyatt et al., 1994; Jaeschke et al., 1994a; Jaeschke et al., 1994b; Lijmer et al., 1999; Oxman et al., 1993; Reid et al., 1995). There are however a few key questions a practitioner can ask themselves when reading articles whether in the peer-reviewed scientific literature, books, or trade magazines.

• Are the results of the study valid?
• Does the information appear to be valid?
• If the information is not based on research, is what is being stated coming from an expert or authoritarian source?
• Do the results or information being presented apply to the client the practitioner is working with?
• Would this evidence help justify a practitioner’s case in a letter of necessity or hearing as compared to opposing evidence or opinions?
• Are the results or information being presented within the practitioner’s clinical and professional intuitive approach to treating the situation?
• Does the author disclose financial interest in and support and for the research?

Specific examples of current peer-reviewed literature available to justify wheelchair seating and mobility interventions will include ultra-lightweight manual wheelchairs, powered mobility, pressure reducing seat cushions and the clinical application of pressure mapping, as well as tilt in space and recline seating.

There is debate as to the effectiveness of costly pressure reducing cushions as compared to lower cost foam type cushions. There have been a few recent randomized clinical trials conducted on the efficacy of pressure reducing cushions in the reduction of pressure sores in the seated surfaces as compared to foam type cushions. Conine et al. (1994) studied a population of 163 elderly people using wheelchairs in nursing homes to compare the effectiveness of Jay cushions to standard slabs of foam. The results showed there was significant difference between the two groups with only 25% of the Jay group developing pressure sores as compared to 41% of the foam group during a three-month observation period. Geyer et al. (2001) conducted a similar pilot study of 32 nursing home residents who use wheelchairs. Segmented foam cushions were compared to pressure reducing cushions over a twelve-month observation. Results showed that 59% of the foam group developed pressure ulcers as compared to 40% of the pressure-reducing group. Although the results did not show a statistical difference between the groups because of low power and sample size, the results are clinically significant and the research protocol has shown feasibility for a larger multi-site trial.

Combined with clinical judgment, pressure-mapping information however has been shown to have some predictive ability to determine risk for the development of pressure sores and may be included in the justification. Brienza et al. (2001) found that in their study of the efficacy pressure reducing cushions for high-risk elderly people who use wheelchairs that people with higher interface pressure measurements had higher associated incidences of sitting-acquired pressure ulcers. Conine et al. (1994) conducted a similar study to look at the effectiveness of Jay cushions for the prevention of pressure sores in a large sample of elderly wheelchair users and found a significantly higher incidence of pressure sore development in people with high peak pressure measurements as compared to those with lower peak pressures.

Expert opinion related to the clinical use of pressure mapping devices also exists in the non-peer-reviewed literature. Shapcott & Levy (1999) and Lipka (1997) describe pressure mapping as being clinically useful for comparing cushion effectiveness, confirming clinical intuition, assessing and justifying the pressure relieving benefits of tilt in space or recline, providing bio-feedback to users pressure relieving effectiveness, and making seating adjustments.

It is well accepted clinically that tilt in space seat frames and reclining backs whether used separately or in combination have physiological and functional benefits and disadvantages. A reclining back has been assigned a Common Procedure Code (HCPCS Code) by the Centers for Medicare and Medicaid Services (CMS formerly HCFA) in the United States and has clinical indicators (some of which are actually contraindicated) and therefore well accepted by most funding sources. Tilt in space however does not have a HCPCS code and therefore less understood and often questioned or denied by funding sources. Some funding sources will deny a tilt system in exchange for a reclining back although there are very significant differences between the two interventions.

Tilt in space alone is beneficial to provide postural stability and comfort, reduce pressure and shear, and allow for gravity assisted repositioning and realignment however can impede function and promote primitive reflexes. Recline alone can reduce pressure in the buttocks and allow for a recumbent position however can cause people to slide out of the seat and increase shear. Combination tilt and recline systems also have similar advantages and disadvantages. Sprigle & Sposato (1997) prepared a comprehensive review article of the evidence that exists in the literature. The following are extrapolations from their article based on the research they reviewed.

Hobson (1992) studied the effects of various seated positions and found greatest reduction in pressures and shear forces with a 50-degree forward lean however this posture is not feasible for people who lack the trunk control to assume it. Pressure alone was reduced significantly with 120 degrees of recline however caused significant shear which would result in a person sliding out of the chair. Twenty degrees of tilt was significant in reducing shear and perhaps more tilt would reduce shear forces further. A combination of tilt and recline could further reduce pressure and shear. Gilsdorf et al. (1990) studied the effects of recline and found it to increase shear in the seat. They also found that transitioning to an upright position increased shear and therefore a likelihood of the person sliding out of the chair. Nachemson (1975) found decreased inter-vertebral disc pressure by reclining the back from 80 to 130 degrees leading to increased comfort however stability was further improved with 6 degrees of seat tilt to counteract the tendency to slide out of the seat when reclined. Pope (1985) found that people who sat in wheelchairs with a semi-reclined back had a tendency to assume a posterior pelvic tilt, kyphotic spine, and flexion of the neck to assume a visual orientation level with the environment. This provides good evidence to consider tilt with recline if recline is being recommended and that recline alone can cause significant shear and the potential for people to slide out of the chair. Tilt therefore is preferred over the use of recline when it comes to reducing pressure and shear as well as for maintaining or adjusting postural alignment or stability.

Nwaobi (1987) looked at the functional effects of tilt in space in children with Cerebral Palsy and found decreased upper extremity function in a tilted position. Results suggest the need for adjustable tilt as being tilted back may assist in pressure relief and postural readjustment however it is not a functional position to be continuously maintained and people need to tilt more upright in order to engage in activities. Using videofluroscopic imaging Hardwick et al. have provided some clinical examples as to the benefits of assuming various positions to assist with swallowing and digestion. Sitting upright assist with swallowing however tilting and repositioning where necessary for relaxation to facilitate stomach emptying and other digestive functions. Schunkewitz et al. (1989) studied the effects of tilt and recline on lower extremity edema and found some improvements in venous stasis in a small sample of three people with spinal cord injuries. The lack of sympathetic muscle tone and dependent position of the lower extremities put people with lower extremity paralysis at risk for deep venous thromboses and edema. Sprigle and Sposato (1997) further discuss the benefit of tilt and recline to address the issues of orthostatic hypotension. The availability of tilt and recline wheelchairs can present opportunities to get people out of bed and actively involved in rehabilitation activities sooner.

There also exist a significant amount of expert opinion related to the indications and contraindications for tilt and recline systems. Kreutz (1997), Lange (200a; 2000b), Pfaff (1993), & Ross (1996) have all written similar articles with the same conclusions about tilt and recline systems similar to what can be found in the more scientific literature.

From this extensive review practitioners can include a significant amount of evidence when recommending tilt in space and recline as well as combination systems. The evidence can also be used to refute a funding source’s decision to approve a reclining back over a tilt in space system.

The following are examples of summary paragraphs demonstrating how evidence can be incorporated into reports and letters of medical necessity. These excerpts can easily be modified to a specific case situation.

Based on our assessment of Ms. G., who is a 35 years old with a 5-year history of L5 paraplegia, we recommend she be provided with an ultra-lightweight manual wheelchair. Her current high-strength lightweight wheelchair is in poor repair and causes her pain in her wrists when she propels long distances. She had an opportunity to try various brands of ultra-lightweight wheelchairs and found the SuperLite to be most effective for her. She also tried powered mobility but is not ready to make this lifestyle change. The ultra-lightweight wheelchair is necessary as it is available with an adjustable rear axle position. Boninger et al. (2000) concluded in their research on axle position and median nerve injuries that providing people with wheelchairs that have an adjustable rear axle position as well as properly fitting the person to the wheelchair can improve propulsion biomechanics and therefore likely reduce injury. Other research (DiGiovine et al,. 2000) showed a significant difference in perceived rider comfort, with the ultra-lightweight wheelchairs being more comfortable than the lightweight wheelchairs therefore potentially reducing low back pain and abandonment of the technology. Ultra-lightweight wheelchairs were also found to be more durable. Using cost and durability data Cooper et al. (1999) found they averaged 673 cycles per dollar cost as compared to 210 cycles per dollar for high-strength wheelchairs and 78 cycles per dollar for standard wheelchairs.

Based on our assessment of Ms. L., who is 64 years old and presents with Type II Diabetes, Peripheral Neuropathy, and Obesity, we recommended she be provided with a powered wheelchair. She is unable to effectively propel any type of manual wheelchair due to her obesity and peripheral neuropathy. Ambulating with assistive devices is not in her medical best interest due to foot ulcers and the risk for amputations. She is also unsafe with ambulation and has fallen frequently in the past placing her at significant risk for fractures and other injuries. She therefore currently has no means of mobility and is bound to a chair in her home. It has been reported in the peer-reviewed literature that powered mobility can provide people who are unable to ambulate or propel manual wheelchairs with the basis for occupational performance including the ability to conduct activities of daily living, fulfill role responsibilities, and participate in the community (Buning, Angelo, & Schmeler, 2001; Evans, 2000; Mills-Tappan & McDonald, 1994). Medically, a powered mobility device replaces impaired upper and lower extremity function in the same manner that prosthetic devices replace missing extremities or other vital organs.

Based on our assessment of Ms. O., who is 82 years old and presents with dementia and general deconditioning following a recent hip fracture, it is recommended that she be provided with a pressure-reducing cushion that also provides postural stability. Based on the trial of several brands and the use of pressure mapping, it was found that the Floam cushion is the most appropriate intervention. This cushion can be modified to accommodate her pelvic obliquity, requires little maintenance, and will allow her to slide forward for transfers. She demonstrated safe and evenly distributed pressure readings on this cushion. It is reported in the literature that elderly people who sit in wheelchairs have a high prevalence of pressure sores and that the use of pressure reducing cushions can reduce this potential. The same studies have also shown that high peak pressures observed on pressure mapping devices are reasonably sensitive in predicting risk for pressure sores (Brienza et al., 2001; Conine et al.,1994; Geyer et al., 2001).

Based on our findings of Mr. T., who is 26 years old and has Muscular Dystrophy with severe proximal muscle weakness and collapsing deformities of the spine, it is recommended that he be provided with power wheelchair with power tilt in space seating system. This system will allow him to independently readjust his posture for repositioning and pressure relief. This is intended to reduce the potential for further spinal deformities, which can lead to compromised vital organ capacity, reduce the potential for pressure sores, and provide comfort. A reclining back is contraindicated as it will increase shear forces in the buttock region and cause him to slide forward in the seat and out of postural alignment compromising his ability to function. It is well documented in the literature that reclining backs can lead to higher shear forces (Hobson, 1992; Nachemson, 1975; Pope, 1985). It is further documented in the literature that tilt in space is effective in redistributing pressure and providing postural realignment (Sprigle & Sposato, 1997).