Methods
Study patients and design
The first study objective examined prevalent dialysis
patients, and consisted of a cross-sectional cohort and a
prospective cohort, with a median follow-up time of
3.6 years. All adult patients (≥18 years) receiving haemodialysis
or peritoneal dialysis in 10 different dialysis units
(with a catchment area of more than two millions persons)
were screened for study participation. They were
eligible to be included in the study if they were in stable
condition and had received maintenance dialysis for more
than 2-months, as previously detailed [17]. Adequate
proficiency in the Norwegian language was compulsory.
Both oral and written information about the study was
provided to the patients, and a signed informed consent
was required for enrolment. The enrolment rate was
72.4%, with 301 patients included (close to 1/3 of the
prevalent dialysis population in Norway). None of the
patients were lost to follow-up. Nurses and physicians
were specifically trained in applying the study instruments,
which consisted of self-administered questionnaires,
as detailed previously [17]. The National
Committee for Medical Health Research Ethics in Norway
approved the study protocol, and concession was
obtained from the National Data Inspectorate. The investigation
was conducted according to the Declaration
of Helsinki.
The second study objective compared the HRQOL in
three groups of diabetes patients: the group of 78 dialysis
patients with diabetes, a group of 127 diabetes patients
with foot ulcers on or below the malleoli, taken from an
anonymised database of patients treated at outpatient
clinics in the Oslo area [16], and a group of 221 diabetes
patients without complications, who had participated in
the Norwegian Survey of Level of Living in 2002. We
also had a group of 5903 persons without diabetes from
the general population [16]. The study of the diabetes
patients with foot ulcers took place five years prior to
our cross-sectional study. Data concerning the time of
renal transplantation and time of death were retrieved
from the Norwegian Renal Registry [4].