3.4 Univariate and multivariate logistic regression analysis
The univariate logistic regression analysis showed that dialysis
vintage, albumin and Kt/V were associated with the development of high
DSI in MHD patients during lockdown period. The multivariate logistic
model’s mean VIF of 1.22 indicates the direct absence of
multicollinearity among variables. Multivariate logistic regression
revealed that dialysis vintage (OR 1.031, 95%CI 1.013-1.050;P =0.001), albumin (OR 0.782, 95%CI 0.627-0.975; P =0.029)
and Kt/V (OR 0.028, 95%CI 0.001-0.556; P =0.019) were significant
risk variables for hige DSI (Table 3).
3.5 Nomogram construction
and validation
The results of multivariate logistic regression were applied to
construct a nomogram of hige DSI in MHD patients, and scores were
assigned to the screened variables based on their regression
coefficients (Figure 3). As shown in nomogram, patients with longer
dialysis vintage, lower albumin levels and Kt/V had a higher risk of
developing high DSI. By summing the scores and locating them on the
total score scale, it was possible to predict the occurrence of high DSI
in individuals during lockdown period.
Internal validation was conducted to evaluate the model’s discrimination
and reduce overfitting bias. The results demonstrated a C-Index of 0.875
for the primary cohort and 0.863 for the internal validation cohort. The
calibration plots showed excellent agreement between the nomogram
predictions and the actual observation of high DSI (Figure 4).
DISCUSSION
Patients on MHD have a heavy burden
of DSI symptoms, but they are often underestimated or even ignored, and
thus undertreated18. COVID-19 has been a challenge to
all humanity, both on physical and psychological level. Its impact is
diverse and it has caused varying degrees of distress to everyone.
Lockdowns increase MHD patients’ anxiety and worry about the treatment
of their disease. In this study, we used validated tools to assess the
presence and severity of patient complaints19. The DSI
is the most common tool used to assess the prevalence and severity of
dialysis-related discomfort in patients with ESRD. A growing number of
epidemiological studies have attempted to use DSI to reveal the
prevalence of physical and emotional symptoms in MHD
patients4,20,21.
In this single-center cohort study, we investigated DSI in patients on
MHD before and during lockdown. We found a significant increase in the
prevalence of individual symptoms and overall symptom severity scores
during the lockdown. Notably, the prevalence of itching, trouble staying
asleep, bone or joint pain, muscle cramps, feeling irritability,
difficulty concentrating, headache, constipation, and feeling nervous
increased compared with pre-lockdown. Examination of symptoms across the
cohort revealed that the most commonly reported symptoms were those
related to fatigue, skin disorders (i.e., dry skin, pruritus), and sleep
disturbances.
These symptoms can be mainly
summarized in terms of physical and psychological aspects. We speculate
that there may be the following reasons for the above changes. First,
the lockdown caused inconvenience to the daily treatment of MHD
patients, which may have led to insufficient treatment of some patients.
Second, the concern of exposure to the virus may directly increase the
psychological burden on MHD patients. Third, patients may not have
received timely and adequate attention from physicians because
physicians were overburdened with the care of the influx of COVID-19
patients. Given the high prevalence of these unpleasant symptoms and
their dominance in the cluster, future studies to identify therapies
that effectively target these symptoms may substantially improve the
health and well-being of a large proportion of dialysis patients.
According to the nomogram, longer
dialysis vintage is a risk factor of high DSI. However, patients with
high albumin levels and Kt/V had a
lower risk of developing high DSI. The Kt/V value, which represents the
adequacy of dialysis, may decrease as dialysis vintage increases.
Studies have shown that MHD patients are more prone to urinary
toxin-related discomfort and vital organ dysfunction when dialysis is
inadequate19,22. Therefore, it is important to reduce
DSI severity by improving dialysis adequacy in patients on MHD. In
addition, we found that low albumin level was a risk factor of high DSI.
Albumin level is an important index for evaluating the nutritional
status of the body. Studies have found that low albumin level is one of
the main causes of serious complications in dialysis
patients23,24. However, we also observed that
nutritional parameters defined by albumin level were associated with a
wider range of symptoms, including decreased energy (feeling tired or
lacking energy), restless legs, muscle discomfort (muscle cramps, muscle
aches), impaired cognition (difficulty concentrating), and overall
symptom burden. Improving the nutritional status of patients on MHD may
be beneficial for reducing discomfort symptoms.
The strengths of our study include the first-time assessment of DSI in
MHD patients during COVID-19 lockdown, rigorous use of a symptom
assessment tool (DSI) that has been validated in the dialysis population
for symptom assessment in MHD patients, and the comprehensive
availability of detailed patient data collected. However, our study has
several limitations. First, the research subjects in this study is not
representative of all HD population; patients who agreed to participate
in the study may have been healthier than those who were not recruited
and, therefore, may have had lower symptom scores than the broader
hemodialysis population. Second, the limited sample size may not have
allowed the detection of significant subgroup analysis-based
interactions. Third, uncomfortable symptoms during dialysis can be
exacerbated by comorbidities, medications, lifestyle and dietary
regimens, renal replacement therapy, and aging. Due to data limitations,
we were unable to examine the relationship between certain dialysis
treatment features (i.e., hemodialysis membranes and medications on
dialysis) and symptom burden.
CONCLUSION
DSI prevalence and severity were higher in MHD patients during lockdown
period than before. The novel predictive nomogram achieved a good
prediction of high DSI in patients on MHD. Using this model, the risk of
high DSI in patients with MHD can be determined earlier.