Since 1950, the life expectancy of individuals with spinal cord injury (SCI) has increased considerably and the mean survival rate after trauma frequently exceeds 30 yr. 1 This asset has been particularly attributed to the improvements in acute care management. Early death from medical complications after SCI, such as respiratory insufficiency, renal failure, or septicemia, has decreased greatly and many people can expect an excellent quality-of-life for several decades if they can avoid secondary complications. Although improvements in acute and subacute rehabilitation have minimized the occurrence of many SCI-related complications, much has to be learned regarding the prevention and management of long-term secondary impairments. It is well known that SCI is likely to modify the functioning of several biological systems (urinary, cutaneous, respiratory, cardiovascular, and musculoskeletal) and that secondary impairments, if they are not managed properly, may have deleterious impacts on the person’s social participation and quality of life.
Urinary tract infection (UTI) is reportedly the most prevalent secondary impairment after SCI. Although its prevalence has been evaluated between 28% and 38%, depending on the duration of the injury, 2 the annual incidence has been estimated at 20 per 100 person-years. 3 Likewise, 80% of individuals with SCI will present at least one episode of UTI over a period of 15 yrs after SCI. Although several definitions are attributed to this phenomenon thereby rendering it difficult to determine its frequency, spasticity is also highly prevalent. High levels of spasticity are generally reached early after SCI (within 1 yr) and then tend to decrease in subsequent years. 4–6 However, some studies have observed that, after 10 yrs postinjury, 35% of individuals with SCI present spasticity severe enough to necessitate medication, 4 and that 40% of the individuals consider their level of spasticity to be a serious problem. 7 Pressure sores have a variable prevalence rate (23%–32%), depending on the severity of the lesion, 3, 5 and they tend to increase with the duration of injury. 5 Several secondary impairments such as autonomic dysreflexia, respiratory complications, joint overuse, and deep venous thrombosis were also reported, but less frequently. 2, 4, 5, 7
It is difficult to compare the occurrence of secondary impairments among individuals with SCI who live in different countries. Prevalence might vary according to the methodologies used for data collection, the socio-political, economic, and sanitary levels of the country where the subjects are living, and the environmental aspect of these countries. Consequently, several reasons justify the design of a prevalence study in Quebec. First, some characteristics of the healthcare system in Quebec, such as universal access and regional differences in care levels, are important. For example, given the vast territory of the Province, many individuals with SCI live in rural regions or in small cities where specialized facilities and well trained staff are not available. Second, the winter climatic conditions that last during 5 to 6 mo tend to reduce greatly the mobility of individuals with disabilities. Variations in the economical status are also a factor that may affect the living conditions of the persons. These factors may increase the prevalence of secondary impairments among individuals with SCI. Estimation of the prevalence of the main secondary complications in long-standing SCI is a prerequisite to resource allocations and the development of specialized care aiming at providing an adequate care management to most individuals across Quebec territory.
The main purpose of this study was to estimate the prevalence of secondary impairments among individuals with SCI in Quebec and to examine the relationships between the prevalence of secondary impairments, the outcome measure, and some independent variables (i.e., severity and duration of the injury, perceived health status and personal income).
A total of 2200 medical files were reviewed at The Rehabilitation Institute of Quebec City and The Montreal Rehabilitation Institute to identify the target population of our study. Medical and sociodemographic information were collected for all individuals who had sustained a traumatic SCI between January 1, 1970, and December 31, 1993 (n = 1771). All nontraumatic injuries were excluded. From this population, a random sampling procedure was applied to recruit an initial sample of about 1000 subjects from whom a response rate of 50% was expected. Authorization was granted by the Commission d’accès à l’information du Québec to obtain the subjects’ current address from the Quebec Health Insurance Plan, a governmental agency that administers the public healthcare system. An initial contact by mail was carried out with 976 potential subjects. The letter described the nature of the study and invited each individual to participate. Thereafter, a questionnaire comprising a set of subsections was mailed to the potential participants of the study. To enhance the amount of responses, we mailed a reminder 2 wk after sending the questionnaire. Three weeks later, a second reminder was mailed, followed by a phone call to all nonrespondents who could be reached.
The questionnaire included an informed consent form and 14 subsections, such as sociodemographic, medical, psychosocial, and environmental information. For the purpose of this study, the medical section was thoroughly analyzed. This section included questions regarding the type and level of injury, and the presence of various secondary impairments (Table 1).
For each potential impairment, a general question was first asked: “Over the last 12 months, have you developed (or suffered of) the following health problem?” Then, specific questions were asked to determine the frequency and evolution of each secondary impairment over this period and the type of medical management (none, medication, hospitalization, others) that has been required. Information was also gathered on the number of medical consultations and the duration of hospitalizations over the last 12 mo before the study. The current perceived health status was rated subjectively from excellent to very bad on a 5-point Likert scale. The research team conducted first a validation process to verify that the questionnaire included all of the necessary information to estimate the prevalence of secondary impairments. Rehabilitation professionals and individuals with SCI performed the second step of the validation process, which involved a review of the questionnaire to ensure that proper and understandable wording was used.
The prevalence of secondary impairments among individuals with SCI was determined using descriptive statistics. Prevalence was also determined for the severity of injury; e.g., the level (tetraplegia or paraplegia) and completeness of injury. To detect a significant difference in the prevalence of secondary impairments between these groups of individuals, χ2 tests of independence were performed.
Further analyses were conducted to assess the relationship between perceived health status and the prevalence of secondary impairments to account for the severity of injury. Given that the occurrence of secondary impairments might be related to the duration of injury, frequency distributions of impairments were established for four subgroups of individuals according to the specific duration of injury (2–7 yr; 8–13 yr; 14–19 yr; and 20–26 yr). Similar groupings were performed with personal income (<$10,000; $10,000–$19,999; $20,000–$39,999; ≥$40,000). Again, χ2 tests of independence were used to detect significant differences between the occurrence of secondary impairments and each of these variables. Finally, to verify a potential combined effect of age and the duration of injury, data were analyzed for a subgroup of individuals for whom age and the duration of injury equaled or exceeded 50 and 20 yr, respectively.
Among the 976 potential subjects contacted by mail, 482 returned the questionnaire with complete data, thus providing a 49% participation rate. A comparison between the current sample and the base population (Table 2) demonstrated that chronologic age and age at the time of injury were slightly lower in the sample as a result of the participation of a lower proportion of individuals aged >60 yr in the study (sample 11.6%vs. population 16.2%). This lower representation of older individuals might limit the generalized results that were applied to this age group.
Information on the subjects’ personal income confirmed that a substantial proportion of individuals with SCI are unable to earn substantial wages and that some of these persons live under the lower income threshold (Table 2), which was fixed to about $15,000 for a person living alone. 8 This situation has a potential influence on various aspects of their life-style; ultimately, it may exacerbate the occurrence of secondary impairments.
Prevalence of Secondary Impairments.
Information on secondary impairments among individuals with SCI in the year preceding the study is presented in Table 3. Regardless of the level and the severity of the lesion, the highest prevalence rates were observed for the following impairments: UTI, spasticity, hypotension, autonomic dysreflexia, and pressure sores. When significant differences appeared with the severity of the lesion, a greater prevalence of secondary impairments were observed in individuals with tetraplegia (spasticity, hypotension, autonomic dysreflexia) and in those with a complete lesion (UTI, autonomic dysreflexia, pressure sores, and shoulder overuse).
A substantial number of individuals reported the presence of upper limb overuse symptoms, particularly related to the shoulder region. Although not always statistically significant, overuse symptoms of the wrist and elbow appeared slightly more frequent among individuals with complete paraplegia. Shoulder overuse symptoms seem to affect significantly more individuals with complete lesion, but are frequent among individuals with incomplete tetraplegia.
Prevalence and Causes of Hospitalizations.
Within 12 mo before this study, 25% of individuals reported hospitalization; of these persons, 16% were hospitalized for ≤2 wk and 9% for >2 wk (Table 4). Among individuals who reported hospitalization, UTI was the most frequent cause, followed by pressure sores and pain.
Prevalence of Secondary Impairments in Relation with Perceived Health Status.
Despite a high prevalence of certain secondary impairments, it was interesting to observe that about two-thirds of the participants perceived their health status as excellent (11%) or good (54%), whereas others perceived it as fair (27%) and only a few individuals perceived it as poor (8%). No relationship was observed between the perceived health status and the level of injury.
Figures 1 and 2 present the prevalence of secondary impairments associated with perceived health status among individuals with tetraplegia and paraplegia, respectively. Despite an absence of statistically significant results in individuals with tetraplegia, there were some tendencies toward an increased prevalence of impairments and a decrease in perceived health status, particularly for autonomic dysreflexia and hypotension. Furthermore, in all of the cases, the higher prevalence was observed in individuals who perceived their health status as poor. Among individuals with paraplegia, the prevalence of UTI and pressure sores showed a clear relationship with perceived health status. The significant relationships observed for autonomic dysreflexia and hypotension are not clear and might be explained by the variation in the level of injury (high or low thoracic and lumbar lesion) that influences the occurrence of these impairments.
Prevalence of Secondary Impairments in Relation with Duration of Injury.
Among individuals with complete tetraplegia, a higher prevalence was observed during the first years postinjury for several secondary impairments (Fig. 3), and particularly for autonomic dysreflexia and hypotension. Fortunately, the prevalence decreased within subsequent years postinjury for spasticity, autonomic dysreflexia, and hypotension. The prevalence of pressure sores also seems to decrease with the duration of injury, but not significantly. Likewise, UTI and shoulder overuse showed a definite pattern, but this is not conclusive because of a lack of statistical significance.
Among the individuals with complete paraplegia (Fig. 4), particular patterns of secondary impairment evolution in relationship to the duration of injury were observed. The prevalence of autonomic dysreflexia, pressures sores, and shoulder overuse increased in the years after the initial period postinjury (2–7 yr), and finally decreased after 15 to 20 yr postinjury. Because of the lack of significance, one should be cautious in interpreting these results. Finally, the prevalence of spasticity decreased over time, whereas shoulder symptoms of overuse increased significantly up to 14 to 19 yr postinjury and then showed an unexpected decrease.
For individuals with incomplete lesions, no statistically significant differences were observed between the prevalence of secondary impairments and the duration of injury (resulting from small sample sizes), except for shoulder overuse in individuals with incomplete paraplegia, which showed a considerable and significant increase (10%–40%) in prevalence after 20 yr postinjury.
Finally, analyses were performed with a subgroup of individuals aged >50 yr with a duration of injury exceeding 20 yr (Fig. 5). Because only 41 individuals met these two criteria, results were combined for individuals with tetraplegia and paraplegia. It seems that UTI, hypotension, and shoulder overuse were reported more frequently by this subsample of older individuals, whereas spasticity, autonomic dysreflexia, and pressure sores seemed to occur less frequently within that same group. However, only shoulder overuse presented a statistically significant difference between the two groups. We observed that spasticity showed a tendency toward a statistically significant difference.
Prevalence of Secondary Impairments in Relationship with Personal Income.
Globally, personal income was related only to a few specific secondary impairments and general indicators of health. Two patterns of association were observed based on a difference between one specific group and three others (Fig. 6). First, the individuals with the highest income showed the lowest prevalence of hypotension (15%) compared with the individuals of the three other categories of incomes (31%–35%). The rate of hospitalization showed a similar pattern but without statistical significance because of a small number of subjects in some categories. However, a significant association was observed when the lowest and the highest groups of income were compared. Twice as many individuals with the lowest income (<$10,000) were hospitalized compared with those who had the highest income (≥40,000) (28%vs. 14%;P = 0.04).
Second, the subjects’ perception of their health status differed significantly with the level of personal incomes. More than 45% of individuals with the lowest income perceived their health as poor or fair, whereas this proportion reached approximately 30% in the individuals who had higher incomes. The prevalence of pressure sores showed a similar pattern of difference but did not reach the level of statistical significance. However, significant difference (P = 0.03) was observed when the prevalence of pressure sores in individuals with the lowest outcome (36%) was compared with that of the individuals of the three other categories of incomes grouped together (25%).
This population-based study was conducted to establish the prevalence of secondary impairments among individuals with long-standing SCI and to determine whether secondary impairments might be associated with personal determinants (severity of injury, perceived health status, duration of injury, income). The main findings of this study are: (1) the observation of a very high prevalence of UTI symptoms among the subjects, (2) the presence of shoulder symptoms of overuse in about 25% of individuals, and (3) the significant association between the occurrence of secondary impairments, perceived health status, and personal income.
Overall, the study results are consistent with those reported by previous studies that assessed secondary impairments among individuals with SCI. Some differences might be attributed to the use of various designs and data collection methods to establish the prevalence of secondary impairments; e.g., medical examination, 2 in-person interviews, 7, 9 and telephone interviews. 5 Furthermore, this study reported prevalence data over a period of 12 mo, whereas other studies were based on incidence data. These methodologic considerations do not totally explain the high prevalence of UTI in our study. The reported rate (56%) of UTI is surprisingly high compared with other reports that have established prevalence rates between 30% and 40%. 2 The difference might be explained as follows: (1) The information requested from the participants covered all symptoms of UTI, and not only the symptoms that required medical management. Likewise, some individuals regularly have symptoms of UTI that are not confirmed by bacteriuria ,which is usually reported in the literature as the criterion for UTI. (2) The period covered by the study (the previous 12 mo) is likely to increase the prevalence compared with a fixed moment in time (e.g., at the time of a medical examination) where the symptoms may not be present. However, it remains possible that UTI was highly prevalent in the study. We may hypothesize that the educational programs aiming at preventing UTI or the available management of UTI are not adequate to decrease this complication to a level comparable with that reported by SCI-specialized centers offering a regular follow-up visit.
Influence of Level and Severity of Injury.
The prevalence of several secondary impairments was higher among individuals with a complete lesion and particularly those with tetraplegia. As reported in the literature about the relationship between secondary impairments and the severity of injury, spasticity occurred more frequently among individuals with a cervical injury, whereas UTI and pressure sores were observed more frequently among individuals with a complete lesion. 4, 9 It is not surprising that, over a 1-yr period, individuals with tetraplegia reported frequent symptoms related to hypotension. In some individuals, quick changes in body position or the accomplishment of a strain activity may produce decreased blood pressure as a result of an inability to avoid blood pooling in the lower limbs.
In this study, upper limb symptoms of overuse (mostly at the shoulder) seemed more frequent among individuals with a complete lesion. This observation is probably the result of the use of a manual wheelchair for locomotion, mostly in individuals with paraplegia. Moreover, the impact of frequent transfers without assistance among those individuals might explain the higher prevalence of elbow and wrist overuse symptoms. Individuals with an incomplete lesion but without functional movements are also prone to develop overuse symptoms. When these overuse symptoms cannot be treated adequately, a chronic condition may develop, and these individuals may face two immediate consequences of their functional independence, namely, social participation and quality-of-life. Therefore, even after rehabilitation, there is an important need to provide access to educational programs on injury prevention based on the use of adequate transfer techniques and assistive devices. Moreover, at the time of their discharge from rehabilitation, these individuals should be convinced that overuse symptoms must be reported and that early management must be undertaken to avoid a deleterious chronic condition.
Secondary Impairments and Perceived Health Status.
Although a substantial number of individuals with SCI had a positive perception of their health, a higher prevalence of secondary impairments were reported by those who perceived their health as fair or poor. Perceived health status has been used in this study to determine whether one’s perception of health was directly related to the occurrence of secondary impairments. The association tended to be verified for almost all secondary impairments among individuals with tetraplegia, but only for UTI and pressure sores among individuals with paraplegia, thus suggesting that the impact of secondary impairments on the general perception of health might be more critical among individuals with tetraplegia.
Secondary Impairments and Duration of Injury.
Given that the survival of individuals with SCI has considerably increased, it is essential to assess the influence of the duration of injury on the development of secondary impairments. The prevalence of these complications is likely to increase with the duration of injury. 2 Studies have suggested that pressure sores , muscle and joint problems, and UTI 2, 3, 5, 9 increase with time, whereas spasticity and autonomic dysreflexia decrease. 5, 9
This study also showed that the reduction of the prevalence of impairments was related to the central nervous system over time (spasticity, autonomic dysreflexia, hypotension) but only in individuals with complete tetraplegia. However, the only other significant association with the duration of injury was the variation in the occurrence of shoulder symptoms of overuse in individuals with paraplegia where the prevalence drastically decreased after 20 yr postinjury. The latter result should be reviewed carefully since it might suggest the presence of a serious problem, depending on the explanation of the phenomenon. First, we may hypothesize that shoulder overuse is less prevalent after 20 yr because of the use of more efficient strategies for mobility and functional independence which come with the experience of living with SCI. Conversely, we may also hypothesize that this decrease in shoulder symptoms is the result of a necessary reduction in mobility and function because of excessive pain or discomfort (causal effect) that limit the occurrence of the symptoms. If corroborated, this situation would definitely impact on the possibility of an optimal social participation and quality-of-life for these individuals with SCI.
The evolution of other secondary impairments are variable between subgroups of individuals, suggesting that the level and severity of lesion are determining factors in the evolution of secondary impairments over time. Actually, there are a few definite patterns of the occurrences of secondary impairments over time, at least for the period of observation (2–26 yr postinjury). More definite trends might be observed after 30 to 35 yr postinjury. Moreover, the small number of individuals within each category limits the statistical power and may explain the observed variability. The cross-sectional aspect of the study is also limiting for the association with the duration of injury. Evolution over time is based on individuals with different postinjury periods and several factors such as changes in medical and rehabilitation practices, as well as improved prevention over time, might interfere with the real effect of time on the occurrence of secondary impairments. Consequently, a longitudinal design is required for the determination of the real impact of aging on secondary impairments.
Secondary Impairments and Personal Income.
As previously described, 10 many individuals with SCI face the problem of earning a decent income. A low socioeconomic level can limit one’s adjustment to disability 1 and life satisfaction. 11 Some dimensions of the life-style, such as poor nutrition habits and cigarette smoking, may also affect health; these habits are more likely to be developed in individuals with a low income. It is not surprising that the individuals with the lowest income showed the highest prevalence of pressure sore and hospitalization. In the same sense, the highest percentage of individuals who perceived their health as poor or fair (45%) was found in this category of income. Consequently, even in a country with a well developed social security system, poverty seems to be associated with a poor health status and the development of secondary impairments among persons with SCI.
This first description of the prevalence of secondary impairments is likely to be a real portrait of the situation of individuals with SCI in Quebec. Very few exclusion criteria were used and with a 49% participation rate of the potential sample, no important difference in the sociodemographic and SCI characteristics were observed between the studied sample and the base population. The only statistically significant difference was approximately 2 yr of difference in chronologic age and age at the time of injury as a result of a lower recruitment in individuals aged >60 yr.
The comparison of our sample with other cohorts of individuals with SCI, particularly in the United States, showed some similarities and differences. Compared with the cohort studied in the Model Systems, 12 age at the time of injury (Model System = 30.7) and gender (male = 81%) are similar in the study results. Although the proportions of individuals with complete tetraplegia and incomplete paraplegia are similar, there is an important difference in incomplete tetraplegia (U.S. Model Systems, 31%; Quebec, 20%) and complete paraplegia (U.S. Model Systems, 27%; Quebec, 38%), which might be explained by differences in the causes of injury. The variations in the proportion of SCI attributable to motor vehicle accidents (45% and 58%, respectively) and acts of violence (17% and 4%, respectively) may partially explain this situation. A difference in the etiology and, consequently, in the severity of injury may also explain some variations in the prevalence of secondary impairments.
The presence of missing values in several questions might have introduced an information bias. Given the hypothesis that missing answers were caused by the absence of the secondary impairments, an overestimation of prevalence would be present in the results. Information bias might also be present because of the self-report methodology. Precisely, UTI prevalence might have been biased because an accurate documentation of UTI is based on laboratory testing. It is, thus, possible that some individuals might have been affected by UTI without being aware of it. Furthermore, the assessment of spasticity might have been underreported as well, when some individuals had their spasticity adequately controlled by medication.
Finally, a number of confounding factors have been taken into consideration in the analyses, including the duration of injury, the level and severity of lesion. However, it should be interesting to consider the assessment of secondary impairment prevalence in relationship to sociodemographic characteristics, intensity, and duration of medical care to provide a more detailed portrait of SCI in Quebec.
This study comprises a first exploration of secondary impairments in a Quebec population-based sample of individuals with SCI. The results showed that a substantial proportion of individuals with SCI still present a high prevalence of secondary impairments many years after rehabilitation. Although some physiologic modifications are likely to increase as a result of the aging process, the high proportion of specific secondary impairments suggests that appropriate preventive education or medical follow-up has not been sufficiently developed. There is an important need to determine the specific impact of these impairments on social participation and quality-of-life for these persons with SCI. In the context of a large territory with a low density of population, specific training for general practitioners in rehabilitation medicine, as well as services such as tele-medicine, are required to maintain an adequate follow-up for individuals with SCI.