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Lack of concealment may lead to selection bias in cluster randomized trials of palliative care

Jordhoy, MS; Fayers, PM; Ahlner-Elmqvist, Marianne LU and Kaasa, S (2002) In Palliative Medicine 16(1). p.43-49
Abstract
Comprehensive palliative care programs are often implemented on a community level, and to evaluate such interventions, randomization by cluster (community) may be the only feasible method. In trials randomizing individual subjects, the importance of proper concealment has been stressed, In cluster randomized trials, however, concealment of individual patient allocation is often impossible. The following risk of selection bias has been given little attention. In the present study, comparing palliative care to conventional care, community health care districts were defined as clusters and randomized. The patients' treatment assignment was determined by the allocation of the cluster in which they resided, and hence predictable by their... (More)
Comprehensive palliative care programs are often implemented on a community level, and to evaluate such interventions, randomization by cluster (community) may be the only feasible method. In trials randomizing individual subjects, the importance of proper concealment has been stressed, In cluster randomized trials, however, concealment of individual patient allocation is often impossible. The following risk of selection bias has been given little attention. In the present study, comparing palliative care to conventional care, community health care districts were defined as clusters and randomized. The patients' treatment assignment was determined by the allocation of the cluster in which they resided, and hence predictable by their address. A biased selection based on practical considerations related to patients' diagnoses and hospital departments was suspected. To explore this, cancer diagnoses were grouped according to local tradition for sharing of treatment responsibility among hospital departments. A significant difference between trial arms in distribution of these groups was revealed and strongly supported our suspicion. The finding carries an important message to future researchers: when using cluster randomization, any evidence of selection bias should be carefully checked and reported. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
concealment, selection bias, palliative care, cluster randomization
in
Palliative Medicine
volume
16
issue
1
pages
43 - 49
publisher
SAGE Publications Inc.
external identifiers
  • wos:000174774600007
  • pmid:11963450
  • scopus:18344382517
ISSN
1477-030X
DOI
10.1191/0269216302pm523oa
language
English
LU publication?
yes
id
5f2af8f4-d716-407b-b007-f709af73c73c (old id 893600)
date added to LUP
2008-01-23 16:31:04
date last changed
2017-08-06 04:23:38
@article{5f2af8f4-d716-407b-b007-f709af73c73c,
  abstract     = {Comprehensive palliative care programs are often implemented on a community level, and to evaluate such interventions, randomization by cluster (community) may be the only feasible method. In trials randomizing individual subjects, the importance of proper concealment has been stressed, In cluster randomized trials, however, concealment of individual patient allocation is often impossible. The following risk of selection bias has been given little attention. In the present study, comparing palliative care to conventional care, community health care districts were defined as clusters and randomized. The patients' treatment assignment was determined by the allocation of the cluster in which they resided, and hence predictable by their address. A biased selection based on practical considerations related to patients' diagnoses and hospital departments was suspected. To explore this, cancer diagnoses were grouped according to local tradition for sharing of treatment responsibility among hospital departments. A significant difference between trial arms in distribution of these groups was revealed and strongly supported our suspicion. The finding carries an important message to future researchers: when using cluster randomization, any evidence of selection bias should be carefully checked and reported.},
  author       = {Jordhoy, MS and Fayers, PM and Ahlner-Elmqvist, Marianne and Kaasa, S},
  issn         = {1477-030X},
  keyword      = {concealment,selection bias,palliative care,cluster randomization},
  language     = {eng},
  number       = {1},
  pages        = {43--49},
  publisher    = {SAGE Publications Inc.},
  series       = {Palliative Medicine},
  title        = {Lack of concealment may lead to selection bias in cluster randomized trials of palliative care},
  url          = {http://dx.doi.org/10.1191/0269216302pm523oa},
  volume       = {16},
  year         = {2002},
}