Quality of Life Correlates Among Individuals with a Spinal Cord Injury: Does Race Matter?

Introduction
The concept of health, like many modern day perceptions, has demonstrated its dynamic nature in that it is no longer limited in scope to the absence of disease or pathology, be it physical or psychological; but rather has come to appreciate the merits of wellness and excellence within these realms. Though this broadened conceptualization was formally adopted by the World Health Organization in 1948 ²⁵, only recently has this precept begun to pervade the present day culture of the western world’s health care systems. As a resultant, of this change in perspective, recent years have seen an emerging effort to evaluate health from a more multidimensional, global perspective.

In light of efforts to appraise health across numerous domains (e.g. physical, psychological, social), there has been mounting attention placed on assessing subjective quality of life (QOL). QOL is a broadly-defined umbrella term that encompasses numerous themes, concepts, and factors such as self-perceptions of general physical health, similar perceptions of psychological health and emotional well-being, meaningful and worthwhile interpersonal relationships, active and satisfying sexual relationships, as well as spirituality to name a few.^29,33 As many of these QOL-related factors have entered into the conceptualization and definition of health, they have similarly become components of interest in the assessment and determination of success in the field of medical rehabilitation.²² This is particularly so in relation to individuals with a spinal cord injury (SCI). Although the field of study addressing QOL is still in its infancy, there is an emerging literature exploring differences in QOL between minority and non-minority individuals with SCI, the primary interest of the present study.

There have been numerous and significant differences consistently documented between minority and non-minority individuals with SCI within the literature. For example, minorities have been observed to report lower levels of satisfaction on measures of career opportunities and finances.¹³ Minorities are less likely to be gainfully employed post-injury, controlling for differences in education, age, and medical characteristics,^{3,7,14,16,17,19-21} and they have been found to report elevated levels of post-injury depression, compared to their Caucasian counterparts.^12,18

While prior studies have indicated that some of these factors are associated with QOL, these relationships have not been observed consistently. These factors may be cursorily divided into three general categories: Physical / Injury factors, Psychosocial factors, and Demographic factors. In terms of Physical / Injury Related Factors, differences in neurological level of injury have fairly consistently failed to yield any variations in QOL.^10,26,34 Time since injury has, however, produced mixed results, with some researchers suggesting that increased time since injury is associated with increased QOL^30,34 and others suggesting that no such relationship exists.²⁶ One study noted that QOL changes during the first two years post-injury but is stable thereafter.⁶

In terms of psychosocial factors, being employed, level of education, social integration and activity, as well as extent of community access have all been found to be associated with increased QOL.^8,30

Demographic factors include variables such as marital status, age, and race. Findings regarding marital status have demonstrated that married individuals with SCI report greater QOL than those who are single.^11,27 Increased age has been associated with lower QOL.²⁶ In regards to race, however, the findings are inconsistent. Various studies suggest that any racial differences in QOL that may be observed are no longer discernible after controlling for various demographic variables (e.g. education, age, income), ^4,8,9,28 while others suggest that race is indeed a noteworthy correlate of QOL in its own right.^15,30

Hypotheses
The purpose of the present study is to investigate potential differences in factors associated with QOL, in individuals with SCI according to race. The underlying thesis is that differences in QOL should not be associated with race; factors that have been shown to be associated with QOL should do so similarly across races. Informed by the existing research discussed above the study’s specific hypotheses are:

1) There are no significant differences (p < .05) in QOL between Caucasian and African American individuals with SCI.

2) There are no significant differences (p < .05) in QOL between individuals with paraplegia and those with tetraplegia amongst either Caucasians or African Americans.

3) Increased number of hours spent working or volunteering is associated with increased QOL in both Caucasians and African Americans, and should be significant at a level of p < .05 for both groups.

4) Greater time spent in recreational or self-improvement activities is associated with increased QOL in both Caucasians and African Americans, and should be significant at a level of p < .05 for both groups.

5) Having a spouse, or being involved in a romantic relationship, is associated with increased QOL in both Caucasians and African Americans, and should be significant at a level of p < .05 for both groups.

6) Increased age is associated with decreased QOL in both Caucasians and African Americans, and should be significant at a level of p < .05 for both groups.

This study utilizes data gathered via a collaborative, longitudinal project amongst five of the national Model Spinal Cord Injury Care Systems (MSCICS) entitled Lifetime Outcomes and Needs: Refining the Understand of Aging with Spinal Cord Injury (Longitudinal Study). It has been funded by the National Institute on Disability Rehabilitation Research since 1990. The data used for this study were collected during the period from 1995-2000.

Participants
Participants were selected from the data base according to the following criteria. All members of this study’s sample frame had experienced a new, traumatic spinal cord injury, were first interviewed for the longitudinal study during the period between 1990 and 1995. They were all participants in the MSCICS and had been injured between ten and 25 years when interviewed. All subjects were at least 18 years of age and people were excluded if their neurological status upon discharge from initial rehabilitation was unknown or classified as minimal deficit. The racial composition of the data used for analyses was limited to Caucasian and African American as the numbers of participants in other racial/ethnic categories were too limited to be included in the analyses in terms of making any statistically valid comparisons. Furthermore, the inclusion of diminutive numbers of other racial and ethnic minority individuals, in order to create a “minority” group for comparison, would yield questionable results in terms of generalizability regarding any of the groups included under said “minority” designation. To this end the sample utilized for analyses did not included individuals of Hispanic ethnicity, be they Caucasian or African American.

In addition, those individuals meeting the International Standards for Neurological Classification of Spinal Cord Injury²Impairment Grade D were excluded, limiting the sample to individuals classified as either with paraplegia or tetraplegia. Though conceptually and scientifically, the inclusion of Grade D individuals was desirable, the sheer lack of sufficient individuals meeting this designation (Caucasian N = 37; African American N = 11) served as a prohibitive factor to inclusion in these analyses. Finally, only those individuals for whom complete data was available on the three primary outcome measures of interest, as described below, were included in this dataset.

Measures

QOL Outcomes. QOL was estimated using the Life Satisfaction Index – Z (LSI-Z),²⁴ an instrument composed of 13 Likert scale items aimed at assessing an individual’s overall satisfaction with life. Higher scores on this index are representative of greater satisfaction with life. In addition, participants were administered the Perceived Stress Scale (PSS),⁵ composed of ten Likert scale items, which is a measure of the degree to which situations in an individual’s life are appraised as stressful. Lower scores on this measure are indicative of lower levels of perceived stress. Finally, participants were posed one face-valid item concerning their estimation of their current QOL. Responses were based upon a four point Likert scale consisting of the following responses: 0 = poor, 1 = fair, 2 = good, 3 = excellent.

Statistical Analyses
Initially, sample demographics were appraised by race. Each of the specific hypotheses was then examined by means of two-tailed independent samples t-tests to investigate between-group differences, as well as bivariate correlations to investigate relationship between factors. For the testing of all hypotheses, the criteria used for statistical significance was an alpha level of p < .05.

		Caucasian (N= 379)	African American (N = 88)	Total Sample (N = 416)
Neurological Status (%)	Para ABC	52.7	56.4	53.4
	Tetra ABC	47.3	43.6	46.6
Gender (%)	Male	80.2	85.9	81.3
	Female	19.8	14.1	18.8
Years Post Injury	Mean	14.67	15.51	14.83
	Standard Deviation	4.29	5.07	4.45
Age	Mean	41.16	43.31	41.56
	Standard Deviation	10.60	10.30	10.56

		N	Mean	SD	t	p - value
LSI-Z	Caucasian	338	11.28	4.49	1.318	.188
	African American	78	10.53	4.72	1.318	.188
PSS	Caucasian	338	12.08	7.33	.470	.639
	African American	78	11.65	6.72	.470	.639
QOL item	Caucasian	338	2.11	.75	1.55	.123
	African American	78	1.96	.78	1.55	.123

Caucasian		N	Mean	SD	t	p - value
LSI-Z	Para	178	11.88	4.19	2.65	.009
	Tetra	160	10.60	4.72	2.65	.009
PSS	Para	178	11.28	6.96	-2.14	.033
	Tetra	160	12.98	7.63	-2.14	.033
QOL item	Para	178	2.09	.72	-.504	.615
	Tetra	160			-.504	.615