Relationship between secondary health conditions and life satisfaction in persons with spinal cord injury: study across twenty-one countries

This study was part of the cross-sectional InSCI community survey.

The InSCI survey was conducted in twenty-one participating countries simultaneously between January 2017 and May 2019 [23, 24]. Due to the absence of a central registry of persons with SCI in many countries, the study allowed for different types of sampling frames, ranging from convenience sampling to defined random samples based on available patient databases. The InSCI study protocol therefore allowed each country to define its sampling design process for the recruitment of participants. Different response modes, including paper and pencil, online questionnaire, telephone or personal interviews, were provided to participants (see Table 1). The study adhered with the national laws and conformed to the Declaration of Helsinki with regulatory approvals obtained from the relevant Institutional Review Boards or Ethical Committees for all countries. Each national study group was responsible for ensuring this compliance. Informed consent was sought from each participant in accordance with national regulations, either in form of written consent; completion of questionnaire (considered as implicit consent); oral consent–recorded; waiver of consent; or consent provided electronically.

A total of 12,591 persons with traumatic or non-traumatic SCI, aged 18 years or older, living in the community, and able to respond to one of the available language versions of the questionnaire were included in the InSCI study. Based on a power analysis, a minimal number of 200 participants per country were recruited [23]. The authors of the present study were granted access to this study sample by the InSCI Study Center at the Swiss Paraplegic Research in Nottwil, Switzerland. For the current analysis, 1530 participants from Switzerland were excluded due to the use of a different response scale for the SHCs (range 1–4) in Switzerland (in distinction to a scale range from 1 to 5 used in all other countries) and a further 562 participants were excluded because they had more than 3 missing values on the SHCs measure. This left a total number of 10,499 participants with SCI representing the following twenty-one countries: Australia, Brazil, China, France, Germany, Greece, Indonesia, Italy, Japan, Lithuania, Malaysia, Morocco, Netherlands, Norway, Poland, Romania, South Africa, South Korea, Spain, Thailand, and the USA. A prior analysis by the authors revealed some differences between those who were included (N = 10,499) and those excluded (N = 562) in relation to level of SCI (paraplegia: 61.9% vs 56.8%; p = 0.022; Cramer’s V = 0.022), years’ post-injury (mean = 12.2 years, SD = 11.4 vs mean = 15.7 years, SD = 13.7; p < 0.001; Cohen’s d = 0.308), and age (mean = 50.1 years, SD = 15.0 vs mean = 57.2 years, SD = 16.5; p < 0.001; Cohen’s d = 0.473). Whereas, there were no differences between these groups for etiology of SCI (p = 0.620), gender (p = 0.168), and severity of SCI (p = 0.502). However, it should be noted that comparison of such large samples are likely to show some differences. The details of these analysis have been included as online-only supplementary file (Supplementary Table).

Participants completed a 125-item self-report questionnaire covering socio-demographic and lesion characteristics, together with questions on activities and participation, environmental and personal factors, health service utilization, and an appraisal of their health and well-being.

To assess the impact of SHCs, a selection of 14 items from the SCI-Secondary Conditions Scale (SCI-SCS) was used [25]. The SCI-SCS has been shown to demonstrate acceptable reliability and validity as a measure in the SCI population [26]. The 14 items concern: sleep problems, bowel dysfunction, urinary tract infections, bladder dysfunction, sexual dysfunction, contractures, spasticity, pressure sores/ulcers, respiratory problems, injury caused by loss of sensation, circulatory problems, autonomic dysreflexia, postural hypotension, and pain. Responses were provided on a 5-point Likert scale ranging from 1 = no problem to 5 = extreme problem. The SCI-SCS response options were modified for the InSCI questionnaire based on advice from the International Scientific Advisory Committee for the study, as it was felt that the original scoring system, incorporating concepts of both severity and frequency of a health condition (i.e., significant or chronic, moderate or occasional, mild or infrequent, and no problem), would make the results more difficult to interpret. Regarding the number of items: two items were omitted, ‘diabetes’ because that is a more remote consequence of SCI and ‘heterotopic ossification’ because of unknown reasons. The two pain items (‘chronic pain’ and ‘joint and muscle pain’) were considered conceptually overlapping items and merged into one pain item. Finally, one item ‘sleep’ was added.

All participants with more than 3 missing answers on SHCs measure were excluded from this study and the SHCs index was therefore calculated as the mean of at least 11 out of 14 items. A higher SHCs index indicates a higher rate of health problems (range 1–5). The 14 items were accompanied by an additional question asking if the participant had received treatment for the SHCs (with option of ‘yes/no’ answer). The variable ‘Treatment index’ was calculated as sum of all responses ‘yes’ to 14 specific health problems, that is, total score of all SHCs that were treated (range 0–14).

To assess LS, five items from the World Health Organization Quality of Life Assessment-5 (WHOQOL-5) were selected [27]. This was specifically developed for cross-cultural purposes and is currently available in 36 languages. The five items assess satisfaction with overall QoL, health, activities of daily living, personal relationships, and living conditions. A 5-point Likert scale ranging from 1 = very dissatisfied to 5 = very satisfied was employed. LS index was calculated as the mean of all 5 items (range 1–5). A higher LS index indicates higher LS. Research suggests that the WHOQOL-5 measure is crossculturally valid in persons with SCI [21, 27].

Age when completing the assessment, age at onset of SCI, and years’ post-injury were calculated from the questionnaire. Other factors included male or female, paraplegia or tetraplegia, complete (no motor function and sensation below the level of lesion) versus incomplete (motor and/or sensory sparing), and etiology of SCI (traumatic and non-traumatic). Income was assessed in deciles of the respective country’s income distribution. Years of education was assessed in total years of formal education before and after onset of SCI, including school and vocational training.

Cronbach’s alpha coefficients of the LS and SHCs indexes for all InSCI countries were calculated [28]. The alpha coefficient of the LS scale was 0.81 (range across countries: 0.74–0.90) and that of the SHCs scale was 0.84 (range: 0.68–0.90). Descriptive statistics were used to present socio-demographic characteristics and the score distributions of the LS and SHCs index. Continuous variables were presented as a mean and standard deviation (SD). Categorical variables were presented in a frequency and percentage format. The coefficient of determination (R-squared) was used to assess the significance and strength of relationships between SHCs and LS. In order to assess association between the occurrence of a particular health problem and its treatment, Cramer’s V was used, which is an effect size measurement for the chi-square test of independence (range 0–1) [29]. The estimated effect sizes that indicate the extent of dissimilarity between the individuals who were included in the analysis and those excluded due to missing data were reported as Cramer’s V (for categorical variables) or Cohen’s d (for continuous variables).

Mixed Model Analysis (Hierarchical Linear Models) were used to test the study hypotheses. The dependent variable was the LS index. Predictors in the analysis were categorized into random effect and fixed effects. Random effects refer to variables that are not the main focus of a study but may impact the dependent variable, and fixed effects are key predictors of the study. The random effect (country) was introduced to account for the relative correlation between data points that fall within one hierarchical level, whereby participants with SCI from one country are more alike than participants with SCI across 21 countries. The fixed effects contained the SHCs index, received treatment, and their interaction, sex, age, level, and extent (completeness) of SCI, years’ post-injury, and etiology of SCI. All statistical analyses were performed using the IBM SPSS Statistics.¹

The InSCI study is the first worldwide SCI survey conducted across 21 countries with varying economic status. InSCI also provides data demonstrating a relationship between SHCs and LS in persons with SCI from these 21 countries. A further strength was the employment of a valid LS measurement tool with cross-cultural sensitivity. Furthermore, appropriate standards were determined for valid translation of the questionnaire in the respective languages. These processes strengthened the validity of comparisons across the 21 countries.

However, the data in the questionnaire on health conditions were self-reported and it was not possible to verify by health professionals, while willingness to disclose sensitive health data may be related to cultural issues, and this may have introduced reporting bias. Another limitation was the variation in sampling frames and use of convenience samples in many of the participating countries, and this may have influenced comparisons between the countries and therefore, the generalizability of the results. Also, given the lack of population-based data on persons with SCI around the world, we were not able to estimate the representativeness of the InSCI sample on a country-by-country basis. Additionally, a wide variation in sample sizes across countries existed, and countries with larger samples were weighted more in the total scores. The different response modes, from online, paper–pencil questionnaires to telephone, or personal interviews could well have influenced the quality of data, such as LS. We have no evidence regarding the equivalence of different response modes using the InSCI survey.

Due to high prevalence of SHCs and their relation to LS following SCI, development of strategies for improved health promotion, supported self-management, surveillance, and early intervention are of great importance. Our findings support the outcomes of previous research where preventive measures of primary care following SCI include regular follow-up by specialized teams and annual comprehensive health examination, as well as access to disability-specific expertise in the form of specialists, regarding common SHCs, such as pain and bowel and bladder complications [15]. Apart from that, there are at least several other options for increasing knowledge about own health status among persons with SCI, such as multimedia patient education resources (labeled SCI-U), developed by rehabilitation professionals and consumers from Canada available in the form of ‘SCI and you’ courses [32]. Alternatively, resources provided by the International Spinal Cord Society include consumer modules (elearnSCI) available online upon earlier registration with this platform.² An example of a program tackling prevention of SHCs following SCI is also the community-based Active Rehabilitation program—a grassroots transfer of practical life and social skills from experienced and active individuals with SCI (peer mentors) to newly-injured individuals [33, 34]. Education sessions during Active Rehabilitation camps are intended to help participants acquire or update knowledge that would allow them to optimally manage their health. These sessions target prevention of pressure sores/ulcers, prevention of urinary tract infections, bowel management, and sexuality and fertility disorders. This peer-based program has been introduced in more than twenty countries in Europe, Africa, and Asia [34‐37].