Læknablaðið : fylgirit - 01.05.2002, Blaðsíða 21

ABSTRACTS / 3 3RD SNC & 2ND SCNN
considered equivalent. Health status is, however, conceptually
preferred and will be used here. Health status questionnaires can be
divided into generic and disease-specific. Generic questionnaires
have been developed for use among a wide range of patient popu-
lations, whereas disease-specific ones are targeted to particular
disorders. In Parkinson’s disease (PD), the PDQ-39 is the most
widely used disease-specific questionnaire. The NHP, SIP, and SF-
36 are the most commonly used generic questionnaires in PD.
Researchers have recently begun attempting to address what
factors contribute to QoL in PD. Studies indicate that depression is
a major contributor, whereas severity of the underlying parkin-
sonism contributes only to a minor extent. However, these studies
have all operationalized QoL as health status and used very similar
sets of independent variables. Other investigators, using patients’
perceived overall QoL as the dependent variable and a broader set
of independent variables, have presented different results. Thus,
various personality characteristics have been found to be of
importance for perceived QoL in PD patients, whereas depression
only has contributed to a minor extent. In a recent cross-sectional
Swedish study, generic and disease-specific health status question-
naires showed only modest to moderate correlations with patients’
perceived overall QoL, similar to that of indices of PD severity,
whereas illness-related distress correlated stronger. In an explora-
tive re-analysis of these data, a forward stepwise multiple regres-
sion analysis was performed, with varying operationalizations
(perceived overall QoL, PDQ-39 summary index, and illness-
related distress) of the dependent variable (DV), i.e., QoL, and
using indices of PD severity, PDQ-39 and NHP subscales, and
perceived overall QoL (when not used as DV) as independent
variables (IVs). Results show that the IVs making significant
contributions to the models differ according to choice of DV, with
the amount of variance explained ranging between 57% and 87%.
Results illustrate that outcomes are related to study design and
choice of variables. Investigators should provide clear definitions,
rationales and conceptual theory when defining DVs and IVs in
QoL studies. Furthermore, these data also illustrate that there is
little support for the validity of using health status questionnaires to
address QoL issues.
Nevertheless, health status questionnaires are valuable and im-
portant in gaining a better understanding of the impact of disease,
as they yield information not obtained by clinical assessments.
However, to allow for valid conclusions, questionnaires must meet
certain criteria regarding, e.g., validity and reliability. We recently
assessed various psychometric properties, several not addressed
before, of the PDQ-39 and the NHP in a Swedish PD sample.
Results indicate that both are in need of further evaluations and
developmental work before they can be considered suitable for
valid use in PD in their present formats. The PDQ-39 thus exhibited
floor effects and suboptimal ability to separate subjects into distinct
groups, as well as bias toward the severe end of the health conti-
nuum. Non-additivity of item scores and non-linearity of scale
scores, along with questionable dimensionality, response category
ambiguities, and signs of differential item functioning (DIF), were
also observed. The NHP behaved similarly but had more floor
effects and poorer ability to separate subjects. However, measure-
ment bias toward the more severe end of the health continuum
among patients with non-extreme scores was less pronounced, and
there were fewer indications of suspect dimensionality and DIF
than in the PDQ-39. These observations illustrate important
measurement problems, and underscore the necessity of systematic
evaluations of health status questionnaires prior to their use in
clinical studies.
Until we have gained a better understanding of “QoL” and until
better, more appropriate measurement tools have been devised,
valid conclusions regarding the nature of QoL and how it is
influenced by various personal, disease, and intervention related
factors, are largely prohibited. Attention should be paid to nomen-
clature and investigators should avoid conclusions beyond what can
be supported by scientific data. Furthermore, close attention must
be paid to the psychometric properties of measurement tools in
order to allow for valid measurement and conclusions. At a time
when patient-reported outcomes and evidence-based health care
are increasingly emphasized, it is of fundamental importance to
emphasize also the need for evidence-based measurement, with
demands on measures to meet appropriate psychometric standards.
L08 - Quality of MS-care in Sweden
MyrÁ
Dept. of Neurology, Karolinska Hospital, Stockholm, Sweden
A group of neurologist and nurses with special interest in MS and
the Swedish society for neurologically disabled decided to investi-
gate important questions if persons with MS are getting the same
care such as rehabilitation, immune modulator treatment, support
from counsellor. Regardless where in Sweden they live.
A questionnaire with 47 items was constituted covering the most
of the aspects of care quality. Nurses in the network where asked to
Participate in the survey and 23 centres in for MS-patients in
Sweden participated.
The survey was made and the Questionnaire was handed out to
patients visiting the various Clinics. Large centres was limited to
100 patients, Smaller centres had one month to complete the survey.
The data had been collected (602 Questionnaires) and is presently
analysed and will be presented at the conference.
L09 - The Danish Interferon-beta experience
Sorensen PS
Dept. of Neurology, Copenhagen University Hospital, Rigshospitalet, Denmark
Abstract not received.
L10 - Genetics of MS in lceland
Gulcher J
deCODE genetics, Reykjavík, Iceland
Abstract not received.
L11 - Follow-up on MS patients treated with interferon-beta and
the importance of neutralising antibodies.
Myhr K-M
The National Multiple Sclerosis Competence Centre, Department of Neurology,
Haukeland Hospital, University of Bergen, Norway
A potential problem with the prolonged clinical use of recombinant
human proteins, including the interferons (IFN), is antibody in-
Læknablaðið/Fylgirit 43 2002/88 21