Physical performance and protein energy wasting in patients starting with nocturnal hemodialysis
compared to conventional hemodialysis: the DiapriFit study

Cardiovascular disease (CVD) is the leading cause of death in patients with
end-stage renal disease (ESRD) (Parfrey 1999). This increased mortality is
attributed to several factors. First, the major hemodynamic impact of
extracellular fluid overload, alternating with periods of dehydration and
hypotension, lead to dilating cardiomyopathy en left ventricular dysfunction.
Second, the continuous hyperphosphataemia as a direct result from diminished
glomerular filtration, often in combination with hypercalcaemia and
hyperparathyroidism, cause gross calcifications in larger blood vessels. These
are strongly associated with the occurrence of cardiovascular events. Third,
protein energy wasting defined as diminished food intake, protein catabolism,
increased energy expenditure, inflammation and fluid retention, contributes to
mortality by increasing cardiovascular and infectious complications.
Nocturnal hemodialysis is characterized by a twice as long and somewhat
less intense hemodialysis treatment. Frequent nocturnal hemodialysis, i.e.
5-6x/week, has been shown to improve volume control, to diminish left
ventricular hypertrophy, and to stabilize blood pressure compared to
conventional hemodialysis (Culleton 2007, Freq HD Network 2011, Ok 2011). It
also provides more intense clearance of solutes, especially of urea and
phosphate. Observational data also show an increase in body weight in patients
treated with nocturnal hemodialysis (Sikkes 2009, Ok 2011). However, other
aspects of protein energy wasting, such as subjective global assessment, body
composition and mid-arm muscle circumference are not yet investigated. Some
data are available on physical aspects of quality-of-life, showing no
difference between conventional versus nocturnal hemodialysis (Rocco 2011;
Schorr 2011, Hall 2012). Furthermore, functional outcomes of protein energy
wasting, such as physical performance, gait speed en muscle strength have
remained underexposed.

The aim of this trial is to study if physical performance improves and protein
energy wasting decreases in patients who change from conventional hemodialysis
to nocturnal hemodialysis, compared to patients who continue their treatment on
conventional hemodialysis.

The study design is a controlled intervention study, which compares starting
nocturnal hemodialysis with continuing conventional hemodialysis . Thus, two
groups of patients will be included:
A. Intervention group: 25-35 patients that have been treated with conventional
hemodialysis (2-3 x/wk, 3-5 h), who start with in-center nocturnal hemodialysis
(3-4 x/wk, 7-9 h), i.e. incident nocturnal hemodialysis patients;
B. Control group: 25-35 patients that have been treated with conventional
hemodialysis (2-3 x/wk, 3-5 hr), who want to continue their treatment with
conventional hemodialysis/hemodiafiltration in the same way.
As it is not possible to randomize patients for nocturnal vs. conventional
hemodialysis, the groups are matched as much as possible regarding criteria
that determine the primary outcome parameter (physical performance). We
therefore recruit every incident nocturnal hemodialysis patient if he/she has
given informed consent, and recruit a control patient on conventional
hemodialysis/hemodiafiltration from another dialysis center after matching for
age (± 5 years), body mass index (± 3 kg/m2), dialysis vintage (< 5 or > 5 yr)
and transplantability (yes/no).
Physical performance and protein energy wasting will be assessed at time
points: t = -2 months, 0 months, and 3, 6 and 12 months follow-up; where t = 0
is the switch from conventional dialysis to nocturnal dialysis for the
intervention group. Two baseline measurements with a 2-month interval will be
assessed in order to adjust for possible *learning effect* during the
assessment of the physical performance tests, and to improve objectiveness of
the baseline measurement .

- there is no risk attributable to participation to this study
- the burden consists of time investment, of which part can be done during
hemodialysis treatment