Patients with end-stage renal disease
(ESRD) receiving dialysis treatment (n=165) in three different dialysis units
(50 patients in Washington, DC; 55 patients in Morgantown, WV; and 60 patients
in Mineola, NY) were asked to respond to a series of questions focusing on
various dimensions of quality of life (QOL), satisfaction with life, and
satisfaction with the care they received from clinical staff while receiving
dialysis treatment. Questions asked
by interviewers included the 16-item McGill Quality of Life Questionnaire (MQOL)
plus the single item overall measure of QOL[i],
the Satisfaction with Life Scale[ii]
(SWLS), and two patient satisfaction scales, including an adaptation from the
Kidney Disease QOL instrument[iii]
and the DiMatteo and Hays patient satisfaction instrument.[iv]
In addition, a series of questions was administered for the purpose of
exploring the impact of other psychosocial dimensions on overall QOL among
individuals with kidney disease. Demographic
information also was collected for each patient to determine variations in
outcomes based on these factors. And
finally, medical information was collected, including length of time on dialysis
(in months), physical symptoms experienced, presence of pain-related symptoms,
the clinician's Karnofsky rating[v],
and average level of hemoglobin (in gm/dl), albumin (in gm/dl), and the
patient's Kt/V ratio.
The analysis strategy had two main objectives.
The first objective was to document, in an exploratory analysis, the
relationship between the patients' various medical and psychosocial
characteristics and the QOL indices. Total scores for each of the QOL and patient satisfaction
scales were calculated and used to test associations with other factors.
In addition, total scores from each of the four McGill QOL subscales
(i.e., physical, psychological, existential, and support domains) were
calculated and tested against other factors.
Pearson correlations, independent sample t-tests, one-way ANOVAs with a
posteriori contrast tests (i.e., least-significant difference), and χ2
tests were used as appropriate, using 2-sided significance levels ≤ .05.
The second objective of the analysis was to explore the
development of a new scale that could be used to document the impact of other
potential dimensions on QOL, including spiritual beliefs and support networks.
Patients were asked to respond to twelve questions on issues focusing on
the meaning and value of spiritual beliefs and level of support and comfort in
talking about their illness to family or friends, other patients, a social
worker or therapist, a priest, rabbi, or other religious person, or their
clinician. To explore the potential underlying dimensions associated
with the 12-item questionnaire, subjects' responses to the questionnaire were
subjected to a principal components analysis (PCA). Bartlett's test of sphericity and the Kaiser-Meyer-Olin
statistic were used to further test the strength of the association among
variables. Reliability analysis
using Cronbach's alpha was also conducted on the reduced scale to test the
internal consistency of scale items. Further
reliability analysis was conducted using a split-half analysis and interpreted
by the Spearman-Brown coefficient. After
the final solution was reached with the PCA and reliability analyses,
regression-method factor scores were calculated using the factor score
coefficients. The resulting
subscales were then correlated with the other validated QOL indices, biomarkers,
and patient satisfaction scales (described above) to determine the associations
among the scales and subscales. Further
differences by patient characteristics were also explored using statistical
tests, as appropriate.
Although nephrologists have for the most part traditionally
relied upon one-dimensional measures of physical functioning (for example, by
examining levels of albumin and hemoglobin and Kt/V ratio) to assess QOL among
patients with end stage renal disease, the findings clearly indicate the
importance of psychosocial factors in defining a patient's overall QOL.
The results also indicate interesting associations between measures of
QOL and various patient characteristics. Results
of the PCA are presented first since these results are incorporated into the
subsequent analyses on associations with other measures of QOL.
The PCA and reliability analyses resulted in two
constructs: spiritual beliefs and patient support network.
These two resulting factors accounted for 45% and 19% of the variance,
respectively, for a total of 64%. The
final standardized item alpha for the reliability analysis was .84.
In addition, the split-half reliability analysis indicated strong
correlations between one half of the variable set and the other (correlation =
.80) and a strong Spearman-Brown coefficient of .89.
The final "spiritual beliefs" construct consisted of four items and
the "support network construct" consisted of five items (from the original
Spiritual beliefs were significantly and positively
associated with the following subscales/scales: The MQOL overall score (r(138)
= .25, p<.01), the MQOL Existential and Support Subscales (r(150)
= .34 and r(148) = .30, respectively, p<.001), the MQOL single
item measure (r(157) = .18,
p<.05), and the SWLS (r(155) = .21; p<.01).
In addition, spiritual beliefs were significantly associated with
patients' perceived support from dialysis staff (r(155) = .22, p<.01).
Age was significantly and positively associated with spiritual beliefs (r(153)
= .21, p<.01), while women compared to men (t(149)=3.57, p<.001)
and racial/ethnic minorities compared to whites (t(150)=3.68, p<.001)
were likely to have higher scores on the spiritual beliefs construct.
Patients who were more likely to speak about their illness
to others in their support network and to gain comfort from this (i.e., support
network construct) also were significantly more likely to score higher on the
following QOL measures compared to patients that scored lower on the support
network measure: The MQOL Existential subscale (r(150)
= .21, p=.01) and the MQOL Support subscale (r(151)
= .29, p<.001). Patients
scoring higher on the support network construct also were more likely to be
satisfied with their doctors and staff (t(136)=2.61, p=.01).
Whites compared to racial/ethnic minorities were likely to
score significantly lower on the support network subscale (t(97)=2.28, p<.05),
while minorities scored significantly lower on the MQOL Psychological subscale
compared to whites (t(85)=2.28, p<.05).
In addition, women were significantly more likely than men to score
higher on the McGill Support subscale (t(136)=2.61, p=.01), while
minorities were significantly more likely to report greater overall average
satisfaction with doctors and staff compared to whites (t(157)=2.50, p<.05).
The relationships between the number of troublesome symptoms reported, presence
of pain-related symptoms reported by patients and QOL scores were also explored.
Fifty-five percent of patients reported having no troublesome symptoms,
while 28% and 17% of patients reported having one, or more than one, troublesome
symptom, respectively. There was a significant inverse dose-response
relationship between the MQOL total score (F(2, 138) = 38.8, p<.0001),
the MQOL physical subscale (F(2, 158) = 180.3, p<.0001), the
single item global measure of QOL (F(2, 162) = 12.5, p<.0001)
and the number of symptoms reported by patients.
The total score on the SWLS also was significantly and inversely
associated with the number of symptoms reported (F(2, 158) = 6.3, p<.01)
(see Figure). Neither the total
score on the spiritual belief construct nor the support network construct was
associated with the number of troublesome symptoms reported by patients.
Further analysis of the type of symptom reported by
patients revealed additional interesting findings.
Types of symptoms were categorized into the following three groups: no
symptoms, pain-related symptoms (e.g., chest pain, stomach pain, pain in
extremities), and other types of troublesome symptoms (e.g., lack of appetite,
trouble sleeping, dyspnea). For the
spiritual beliefs construct, 67.7% of responses associated with pain-related
symptoms fell below the median score compared to only 46.6% and 49.3% of the
"no symptoms" and "other symptoms" groups, respectively.
The same pattern was identified for the support network construct: 64.5%
of responses in the pain category fell below the median score compared to 47.8%
and 48.7% of the "no symptoms" and "other symptoms" categories.
These overall results point to the potential association between symptom
reduction - and particularly, pain management - and QOL, and represent a
point of intervention for clinicians.
It is interesting to note that none of the
biomarkers (i.e., hemoglobin, albumin, and Kt/V) was significantly associated
with the patient's QOL, including both the spiritual beliefs and support
network constructs. In fact, the
only significant association between physical functioning and QOL was found
between the Karnofsky rating and overall score on the SWLS (r(160)=.17, p<.05).
The results of this study are promising and indicate
potential points of intervention for improving the QOL among dialysis patients.
Better assessment and treatment of patients' symptoms would seem to have a
very positive effect on ESRD patients' QOL. Since pain was the most frequently
reported symptom, better pain management for ESRD patients appears to be a
priority to improve ESRD patient QOL. In addition, the lack of any significant
association between the various biomarkers studied and quality of life
underscores the relative importance of psychosocial and spiritual dimensions
from the patient's perspective. The
results also indicate the utility of a brief, 9-item scale that can be used to
document the patient's spiritual beliefs and support network.
Although more research is needed to further validate this scale, when
administered in conjunction with other QOL scales, it can provide a more
comprehensive assessment of a patient's psychosocial needs.
[i] Cohen R, Mount BM, Strobel MG, Bui F. The McGill Quality of Life Questionnaire: A Measure of Quality of Life Appropriate for People with Advanced Disease. Pall Med 1995; 9: 207-219.
[ii] Diener E, Emmons R, Larsen J, Griffin, S. The Satisfaction with Life Scale. J Personality Assessment 1985; 49 (1): 71-75.
[iii] RAND, KDQOL-SFTM User's Manual, 1993.
[iv] DiMatteo MR, Hays R. The Significance of Patients' Perceptions of Physician Conduct: A Study of Patient Satisfaction in a Family Practice Center. J Community Health 1980; 6: 18-34.
[v] Karnofsky DA, Burchenal JH. The Clinical Evaluation of Chemotherapeutic Agents in Cancer, in Evaluation of Chemotherapeutic Agents in Cancer, ed. Macleod CM. New York: Columbia University Press, 1949, pp 191-205.
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Promoting Excellence in End-of-Life Care is a national program of The Robert Wood Johnson Foundation dedicated to long-term changes in health care institutions to substantially improve care for dying people and their families. Visit PromotingExcellence.org for more resources.