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Value added: increasing the power to assess treatment outcome in joint haemorrhages

Donfield, S. M.; Astermark, Jan LU ; Lail, A. E.; Gilbert, S. A. and Berntorp, Erik LU (2008) In Haemophilia 14(2). p.276-280
Abstract
Subject reports of efficacy of treatment of haemophilia-related joint bleeding are by definition subjective, yet are often the primary outcome in studies comparing therapies. Verbal descriptors such as effective, partially effective, poorly effective, not effective are treated as dichotomous or categorical variables in analyses, lowering the statistical power relative to that which might be achieved with a continuous variable. The aims of this study were to examine reports of pain recorded on a 100-mm visual analogue scale (VAS) during the course of joint bleeding; determine whether pain varied by treatment period among pairs reporting discordant outcomes on a verbal scale (one product effective, the other not effective); test whether the... (More)
Subject reports of efficacy of treatment of haemophilia-related joint bleeding are by definition subjective, yet are often the primary outcome in studies comparing therapies. Verbal descriptors such as effective, partially effective, poorly effective, not effective are treated as dichotomous or categorical variables in analyses, lowering the statistical power relative to that which might be achieved with a continuous variable. The aims of this study were to examine reports of pain recorded on a 100-mm visual analogue scale (VAS) during the course of joint bleeding; determine whether pain varied by treatment period among pairs reporting discordant outcomes on a verbal scale (one product effective, the other not effective); test whether the two products under study were equivalent with respect to VAS scores; and evaluate their relationship to verbal reports of efficacy. Data from the international, prospective, randomized, crossover FEIBA NovoSeven Comparative study of two bypassing agents used for treatment of 96 bleeding episodes in 48 participants were examined. VAS scores were associated with verbal descriptors of efficacy at every time point, and were equivalent between treatment periods. There were differences in mean scores at time points at which participants rated one treatment effective, the other not effective. As a continuous variable, the VAS score may have more power than a dichotomous variable and when used with verbal descriptions of efficacy can improve the overall accuracy of assessment. This report highlights an important consideration in the selection of outcome measurement that can be generalized to other haemophilia treatment research. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
inhibitors, bypassing agents, efficacy measurement, visual analogue, scale
in
Haemophilia
volume
14
issue
2
pages
276 - 280
publisher
Federation of European Neuroscience Societies and Blackwell Publishing Ltd
external identifiers
  • wos:000253626100007
  • scopus:40349113432
ISSN
1351-8216
DOI
10.1111/j.1365-2516.2007.01638.x
language
English
LU publication?
yes
id
f546f130-c953-474e-8073-84bce51ba68a (old id 1193294)
date added to LUP
2008-09-05 14:19:49
date last changed
2017-04-02 03:33:34
@article{f546f130-c953-474e-8073-84bce51ba68a,
  abstract     = {Subject reports of efficacy of treatment of haemophilia-related joint bleeding are by definition subjective, yet are often the primary outcome in studies comparing therapies. Verbal descriptors such as effective, partially effective, poorly effective, not effective are treated as dichotomous or categorical variables in analyses, lowering the statistical power relative to that which might be achieved with a continuous variable. The aims of this study were to examine reports of pain recorded on a 100-mm visual analogue scale (VAS) during the course of joint bleeding; determine whether pain varied by treatment period among pairs reporting discordant outcomes on a verbal scale (one product effective, the other not effective); test whether the two products under study were equivalent with respect to VAS scores; and evaluate their relationship to verbal reports of efficacy. Data from the international, prospective, randomized, crossover FEIBA NovoSeven Comparative study of two bypassing agents used for treatment of 96 bleeding episodes in 48 participants were examined. VAS scores were associated with verbal descriptors of efficacy at every time point, and were equivalent between treatment periods. There were differences in mean scores at time points at which participants rated one treatment effective, the other not effective. As a continuous variable, the VAS score may have more power than a dichotomous variable and when used with verbal descriptions of efficacy can improve the overall accuracy of assessment. This report highlights an important consideration in the selection of outcome measurement that can be generalized to other haemophilia treatment research.},
  author       = {Donfield, S. M. and Astermark, Jan and Lail, A. E. and Gilbert, S. A. and Berntorp, Erik},
  issn         = {1351-8216},
  keyword      = {inhibitors,bypassing agents,efficacy measurement,visual analogue,scale},
  language     = {eng},
  number       = {2},
  pages        = {276--280},
  publisher    = {Federation of European Neuroscience Societies and Blackwell Publishing Ltd},
  series       = {Haemophilia},
  title        = {Value added: increasing the power to assess treatment outcome in joint haemorrhages},
  url          = {http://dx.doi.org/10.1111/j.1365-2516.2007.01638.x},
  volume       = {14},
  year         = {2008},
}