Physical capacity in rehabilitation of persons with spinal cord injury

• Janneke Haisma, MD (Researcher)
• Henk Stam, MD, PhD (Project leader)
• Lucas van der Woude, PhD (Project leader)
• Hans Bussmann, PhD (Project leader)
• Annet Dallmeijer, PhD
• Michael Bergen, PhD
• Tebbe Sluis, MD

On April 23, 2008, Janneke Haisma defended her dissertation entitled:Physical capacity and complications during and after inpatient rehabilitation for spinal cord injury.

Summary

Neurological deficit following a spinal cord injury (SCI) results in a low physical capacity and a high risk of medical complications. The low physical capacity makes activities of daily living (ADLs) more strenuous, and could make patients dependent on the assistance of others for seemingly straightforward activities. Most patients with SCI are wheelchair-bound, which interferes with accessibility. This, together with the constant threat of complications, the strain of ADLs and the physical dependence, might discourage participation in work or social activities. We hypothesized that the following sequence of events occurs: a low physical capacity and complications make activities strenuous, this reduces activity and social participation, the resultant inactive lifestyle further reduces physical capacity, and exposes the patient to more complica­tions, which in turn reduce activity, and so on.

By analyzing changes in physical capacity and the occurrence of complications, their respective determinants and risk factors, and their interactions with physical independence and functional status, this thesis aimed to provide knowledge to help prevent this proposed sequence of events, and to help improve rehabilitation for SCI. The thesis was based on prospective data collected in the Umbrella project, which is part of the eight rehabilitation research programs of The Netherlands Orga­nization of Research and Development (Zon-Mw): 'Physical strain, work capacity and mechanisms of restoration of mobility in the rehabilitation of persons with a spinal cord injury'. Research assistants in eight Dutch rehabilitation centres, with a specialized SCI unit collected data on 225 patients with SCI, who were wheelchair­-bound at initial rehabilitation.

The introductory Chapter 1 describes SCI and its possible consequences. Physical capacity and medical complications are positioned in the International Classification of Functioning, Disability and Health (ICF) model of health. This model shows how physical capacity and complications could interact with other aspects of function­ing. Chapter 1 provides a description of the Umbrella project and concludes with an outline of this thesis. Physical capacity is defined as the joint ability of muscles and respiratory and cardiovascular systems to attain a peak level of activity. Both the separate functions of these systems, and their combined functions, inform us about the level of physical capacity. This means that in addition to components of physical capacity, such as muscle strength and respiratory function, the endurance capacity (peak oxygen uptake and peak power output) is investigated.

In order to address the complexity of defining or quantifying physical capacity, Chapter 2 provides a literature review, which summarizes the reported level of physical capacity, and critically evaluates how physical capacity was measured fol­lowing SCI. Based on topic-related criteria and methodological criteria, we selected 52 articles for the review. Overall, the reported level of physical capacity was low, and because those with a tetraplegia and women were underrepresented in the study samples, the actual level of physical capacity may be even less promising fol­lowing SCI. Variation in results between the publications was caused by differences in the study population and in research protocols, e.g. the chosen mode of exercise or measuring device. Chapter 2 provides suggestions as to which components of physical capacity should be determined, and the appropriate methods to be used. As long as one takes into consideration the effect of differences in populations and protocols, the descriptive data reported in Chapter 2 can be used as reference material in rehabilitation and training.

Low physical capacity following SCI has been described in Chapter 2. However, we assume that during initial rehabilitation strength or endurance training will improve physical capacity. After discharge, when the environment may not be fully adapted to the patient's needs, a decline in activity may negatively influence physical capacity. To gain insight into these influences Chapter 3 used the prospective data to describe changes in physical capacity over time, how these changes interact with age, gender and level and completeness of the lesion, and how changes in compo­nents of physical capacity interact with one another. All the investigated components of physical capacity improved significantly during inpatient rehabilitation. The peak oxygen uptake and the peak power output, for example, improved by 24% and 41%, respectively. Not all components continued to improve during the year after discharge, and the overall level of physical capacity remained relatively low. In anticipation of a potential decline in physical capacity in association with an expected level of relative inactivity after discharge, we recommend the structural registration and evaluation of physical capacity at follow-up visits. Women, the elderly and those with a tetraplegia had a lower physical capacity. Over time, gender-related differences and the negative association with age became larger, whereas the nega­tive association with a tetraplegia became smaller after discharge. In order to allow patients to develop their maximal potential of physical capacity, we recommended a further exploration of the reasons behind the differences in recovery between subpopulations. The separate components of physical capacity were in fact related. However, whether training of one component actually improves the other needs to be established in future intervention studies. At the start of rehabilitation, patients, relatives and clinicians need to be informed about the expected prognosis, which will help to set realistic rehabilitation targets.

In Chapter 3 we established changes over time as well as several associations, which allow us to estimate prognoses for different populations. However, these results were based on combinations of cross-sectional and longitudinal associations. Furthermore, they included differences between subpopulations that can be taken into account but, however, cannot be changed. Therefore, the aim of Chapter 4 was to use the prospective data to make prognostic models, which also included some modifiable potential predictors. Muscle strength and peak power output were relatively well predicted, with explained variances ranging between 42% and 84%. Not surprisingly, most variation in outcome (51% to 82%) was explained by prior physical capacity, but (although their contribution was modest) former education and employment, stabilization of the spine, smoking, and body mass index were significant predictors of physical capacity at follow-up. When we compared the predicted outcome with the observed outcome in the same study sample, the accuracy of the models was limited. Therefore, we suggested that the models be used to estimate prognosis only in combination with clinical expertise and knowledge of the individual patient.

Impairment and disability may not only be caused by the neurological deficit following SCI, but can also arise from complications. A complication is defined as a condition that follows the SCI in time, and for which the risk is increased after SCI. Chapter 5 describes changes in the occurrence of complications during and after inpatient rehabilitation, as well as risk factors of these complications. Most patients reported pain or showed spasticity at physical examination. There were no significant changes in the occurrence of complications and, therefore, complications remained a threat even during the year after injury, when urinary tract infections and pressure sores, for example, affected 49% and 36% of the study population, respec­tively. Those with a tetraplegia, a complete lesion or a traumatic lesion were at risk of several complications. Additionally, increases in age or in body mass index were significant risk factors. During rehabilitation and at regular follow-up visits clinicians need to systematically address and investigate the presence of complications.

Initial spinal cord rehabilitation programs include the treatment or prevention of complications, and the enhancement of physical capacity. Changes in physical capacity have been described in Chapter 3, but an exploration of the effect of reha­bilitation programs on the recovery of physical capacity was considered additionally meaningful. Unfortunately, we could not determine the effect of the contents and intensity of training programs. However, we assumed that the duration of active rehabilitation, during which the patient participated in functional, strength and endur­ance training in the wheelchair, would correlate with the given hours of therapy. Therefore, in Chapter 6 we investigated the complex interactions between the level of physical capacity on the one hand, and the duration of phases of rehabilitation and the occurrence of complications on the other. Results showed that the duration of active rehabilitation, bed rest and the occurrence of complications after discharge were negatively associated with the level of physical capacity. Furthermore, duration of active rehabilitation and spasticity were negatively associated with the recovery of physical capacity over time. Future studies need to systematically investigate the effect of rehabilitation programs on the level of physical capacity.

Besides insight into physical capacity, the expected level of physical independence or functional status provides important and meaningful information for patients, relatives and clinicians. We hypothesized that patients require a basic level of physi­cal capacity and no hindrance from complications before they can be active and involved. Therefore, Chapter 7 describes changes in physical independence over time. Furthermore, we determined the value of physical capacity and complications in predicting physical independence and functional status one year after discharge. The level of physical independence improved during inpatient rehabilitation and remained unchanged thereafter, whereas the likelihood of independence contin­ued to improve. In addition to discharge dependency status and completeness of the lesion, physical capacity and the absence of complications at discharge were positively associated with physical independence and functional status at follow-up. These interactions suggest that not only functional training, but also the training of physical capacity and the treatment or prevention of complications could contribute to functional prognosis, but future intervention studies need to establish these pro­posed effects.

Finally, Chapter 8 discusses the main findings of the studies, how these fit into the ICF model, and whether they correspond with the aforementioned sequence of events following SCI. We also addressed considerations related to the multi-centre prospective study and discussed issues applying specifically to the outcome mea­sures and analyses in this thesis. We aimed to translate the findings of this thesis into meaningful clinical messages, and have provided suggestions for future research.

You can read more information about the progress of this project in the newsletters: Newsletter 2005 and Newsletter 2007

Publications from this thesis

• Physical capacity in wheelchair-dependent persons with a spinal cord injury: a critical review of the literature. Haisma JA, van der Woude LH, Stam HJ, Bergen MP, Sluis TA, Bussmann JB. Spinal Cord. 44(11): 642-652, 2006.
• Changes in physical capacity during and after inpatient rehabilitation in subjects with a spinal cord injury. Haisma JA, Bussmann JB, Stam HJ, Sluis TA, Bergen MP, Dallmeijer AJ, de Groot S, van der Woude LH. Arch Phys Med Rehabil, 87(6): 741-8, 2006.
• Prognostic models for physical capacity at discharge and 1 year postdischarge from rehabilitation in persons with spinal cord injury. Haisma JA, van der Woude LH, Stam HJ, Bergen MP, Sluis TA, de Groot S, Dallmeijer AJ, Bussmann JB. Arch Phys Med Rehabil 88(12): 1694-703, 2007.
• Complications following spinal cord injury: occurrence and risk factors in a longitudinal study during and after inpatient rehabilitation. Haisma JA, van der Woude LH, Stam HJ, Bergen MP, Sluis TA, Post MW, Bussmann JB. J Rehabil Med. 39(5):393-8, 2007.
• Physical fitness in people with a spinal cord injury: the association with complications and duration of rehabilitation. Haisma JA, Bussmann JB, Stam HJ, Sluis TA, Bergen MP, Post MW, Dallmeijer AJ, van der Woude LH. Clin. Rehabil. 21(10): 932-40, 2007.
• Functional independence and health-related functional status following a spinal cord injury: a prospective study on the association with physical capacity and complications. Haisma JA, Bussmann JB, Stam HJ, Bergen MP, Sluis TA, Van den Berg-Emons HJ, Post MW, Van der Woude LH. J Rehabil Med. 40(10): 812-8, 2008.