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Enforced bedrest
CORRESPONDENCE
Enforced bedrest Sir—Chris Allen and colleagues (Oct 9, p 1229)1 present an excellent review of randomised controlled trials (RCTs) of the effects of enforced bedrest. However, it is unfortunate that they limit their search to RCTs— one of the least appropriate methodologies for studying the effects of policies on health outcomes. Inclusion of balanced incomplete block and ward cross-over design studies might have improved the validity of the findings. How Allen and colleagues selected papers to include in their review also concerns us. The researchers describe a trial of treatment for low back pain in the armed forces that they did not include because the environment in the two treatment groups was different. By this they presumably meant the control treatment, which consisted of enforced exercise. However, in this trial, in which the exercised patients did badly compared with those on bedrest, the control group was probably better defined than in the 40 accepted studies. The study they describe was significant because allowing patients to act as they feel fit is very different from making them do things for which they do not—eg, expecting old people to sit out of bed for long periods when they are ill or in shock having had an operation. The evidence for the benefits of enforced mobilisation, or to be more accurate, of sitting in a chair, is scant. In a crossover trial we did2 in elderly patients who had had hip and knee surgery, a group for whom early ambulation is thought to be particularly beneficial, chairnursing for no more than 2 h per session was compared with unlimited chairnursing (median 6 h), with incidence of pressure sores as the outcome measure. Patients on limited chairnursing showed a significant reduction of sores compared with the unlimited group (7% vs 63 [95% CI ⫺77% to ⫺36%], respectively; p<0·001). The patients developed fewer chest infections, less constipation and ankle oedema, and were more likely to be independently mobile 14 days after their operation. There was no increase in urinarytract infection or deep vein thrombosis. Care should therefore be taken that this review by Allen and colleagues is not used to promote thoughtless implementation of policies to keep all patients out of bed, regardless of their condition and wishes, but rather to
844
stimulate research into the neglected area of the formulation of effective mobilisation regimes.
increased interest and funding for randomised trials of commonly used non-drug interventions.
*K S Gebhardt, M R Bliss
Paul Glasziou, Chris Allen, Chris Del Mar
*Surgical and Clinical Support Services, St Georges Hospital, London SW17 0QT, UK, and 49 Groombridge Road, London
Department of Social and Preventive Medicine, University of Queensland, Medical School, Herston, Queensland 4006, Australia
1
1
2
Allen C, Glasziou P, Del Mar C. Bedrest: a potentially harmful treatment needing more careful evaluation. Lancet 1999; 354: 1229–33. Gebhardt KS, Bliss MR. Preventing pressure sores in orthopaedic patients—is prolonged chairnursing detrimental? J Tissue Viabil 1994; 4: 51–54.
Authors’ reply Sir—Enforced bedrest should be replaced by enforced activity. We would be disappointed if this was the message that readers got from our review. Our review focused on the effects of enforced bedrest. The alternative treatment was not always clearly stated in the studies we looked at, and so we could not define the most effective form of mobilisation. This is why we tentatively suggested that individual patients may be best placed to judge how much rest they can manage. K S Gebhardt and M R Bliss appear to misunderstand the strength of different types of randomised trials. Randomisation may include units other than individual patients—eg, eye or ear (within individual patients), household, hospital ward or block (as suggested), and even region. All are valid provided the analysis is undertaken by the unit of randomisation. Designs of randomised trials can have many variants: no crossover, a single crossover, and multiple crossovers. Each of these is valid provided the first period is randomly allocated.1 In our review we included any randomised trial, irrespective of the unit of randomisation and the number of crossovers. Gebhardt and Bliss are quite right to suggest that more trials are needed to define the optimal approach to mobilisation, particularly in the elderly. Unfortunately, bedrest does not have a patent and hence attracts no royalties. Accordingly, little research is funded in this area compared with patented pharmaceuticals. In the USA alone, the costs of enforced bedrest in pregnancy—which women generally find disruptive and unpleasant—have been estimated to be between US$250 million and several billion.2 A rational research funding policy would recognise that it is worth spending a small portion of this total cost on finding out whether such use of bed rest leads to net benefit or a net harm. Hopefully, our review will spark
2
Senn S. Cross-over trials in clinical research. John Wiley & Sons: Chichester, 1993. Goldenberg RL, Oliver SP, Bronstein J, Cutter GR, Andrews WW, Mennemeyer ST. Bed rest in pregnancy. Obstet Gynecol 1994; 84: 131–36.
Swedish in-vitro fertilisation study Sir—The Nov 6 commentary 1 by Nicholas Fisk and Geoffrey Trew and the article by T Bergh and colleagues in the same issue (p 1579)2 outline the risks associated with multiple pregnancy (especially triplets). This risk is associated with all multiple pregnancies and not just those created as a result of assisted conception. Both articles advocate a reduction in the number of embryos transferred to two or even one. The commentary maintains that the transfer of two embryos would not reduce the pregnancy rate. Furthermore, Templeton and Morris3 asserted that where more than four embryos were available for transfer (not two, as mentioned in the commentary) the live birth rate was not affected by the transfer of two or three embryos although there was a significant reduction in multiple pregnancy rate when two were transferred. This study has a major flaw because vital information that may affect the outcome, such as embryo quality, was not available to the investigators and the assumption is made that where two embryos are transferred, the embryo quality is similar to that in cases in which three embryos were transferred. In our clinic, which handles the largest number of in-vitro fertilsation (IVF) cycles in the UK, it is our policy to advise the transfer of two embryos either if more than four embryos are available in women younger than 38 years when the embryo quality is good, or if a patient will not consider fetal reduction should she have a triplet pregnancy. If the embryo quality is not good or is variable, if the patient has had repeated failed cycles in the past, or if the patient will consider fetal reduction should she have a triplet pregnancy, patients may opt for three embryos to be transferred. Frisk and Trew cite two controlled studies in which transfer of two
THE LANCET • Vol 355 • March 4, 2000
Enforced bedrest Sir—Chris Allen and colleagues (Oct 9, p 1229)1 present an excellent review of randomised controlled trials (RCTs) of the effects of enforced bedrest. However, it is unfortunate that they limit their search to RCTs— one of the least appropriate methodologies for studying the effects of policies on health outcomes. Inclusion of balanced incomplete block and ward cross-over design studies might have improved the validity of the findings. How Allen and colleagues selected papers to include in their review also concerns us. The researchers describe a trial of treatment for low back pain in the armed forces that they did not include because the environment in the two treatment groups was different. By this they presumably meant the control treatment, which consisted of enforced exercise. However, in this trial, in which the exercised patients did badly compared with those on bedrest, the control group was probably better defined than in the 40 accepted studies. The study they describe was significant because allowing patients to act as they feel fit is very different from making them do things for which they do not—eg, expecting old people to sit out of bed for long periods when they are ill or in shock having had an operation. The evidence for the benefits of enforced mobilisation, or to be more accurate, of sitting in a chair, is scant. In a crossover trial we did2 in elderly patients who had had hip and knee surgery, a group for whom early ambulation is thought to be particularly beneficial, chairnursing for no more than 2 h per session was compared with unlimited chairnursing (median 6 h), with incidence of pressure sores as the outcome measure. Patients on limited chairnursing showed a significant reduction of sores compared with the unlimited group (7% vs 63 [95% CI ⫺77% to ⫺36%], respectively; p<0·001). The patients developed fewer chest infections, less constipation and ankle oedema, and were more likely to be independently mobile 14 days after their operation. There was no increase in urinarytract infection or deep vein thrombosis. Care should therefore be taken that this review by Allen and colleagues is not used to promote thoughtless implementation of policies to keep all patients out of bed, regardless of their condition and wishes, but rather to
844
stimulate research into the neglected area of the formulation of effective mobilisation regimes.
increased interest and funding for randomised trials of commonly used non-drug interventions.
*K S Gebhardt, M R Bliss
Paul Glasziou, Chris Allen, Chris Del Mar
*Surgical and Clinical Support Services, St Georges Hospital, London SW17 0QT, UK, and 49 Groombridge Road, London
Department of Social and Preventive Medicine, University of Queensland, Medical School, Herston, Queensland 4006, Australia
1
1
2
Allen C, Glasziou P, Del Mar C. Bedrest: a potentially harmful treatment needing more careful evaluation. Lancet 1999; 354: 1229–33. Gebhardt KS, Bliss MR. Preventing pressure sores in orthopaedic patients—is prolonged chairnursing detrimental? J Tissue Viabil 1994; 4: 51–54.
Authors’ reply Sir—Enforced bedrest should be replaced by enforced activity. We would be disappointed if this was the message that readers got from our review. Our review focused on the effects of enforced bedrest. The alternative treatment was not always clearly stated in the studies we looked at, and so we could not define the most effective form of mobilisation. This is why we tentatively suggested that individual patients may be best placed to judge how much rest they can manage. K S Gebhardt and M R Bliss appear to misunderstand the strength of different types of randomised trials. Randomisation may include units other than individual patients—eg, eye or ear (within individual patients), household, hospital ward or block (as suggested), and even region. All are valid provided the analysis is undertaken by the unit of randomisation. Designs of randomised trials can have many variants: no crossover, a single crossover, and multiple crossovers. Each of these is valid provided the first period is randomly allocated.1 In our review we included any randomised trial, irrespective of the unit of randomisation and the number of crossovers. Gebhardt and Bliss are quite right to suggest that more trials are needed to define the optimal approach to mobilisation, particularly in the elderly. Unfortunately, bedrest does not have a patent and hence attracts no royalties. Accordingly, little research is funded in this area compared with patented pharmaceuticals. In the USA alone, the costs of enforced bedrest in pregnancy—which women generally find disruptive and unpleasant—have been estimated to be between US$250 million and several billion.2 A rational research funding policy would recognise that it is worth spending a small portion of this total cost on finding out whether such use of bed rest leads to net benefit or a net harm. Hopefully, our review will spark
2
Senn S. Cross-over trials in clinical research. John Wiley & Sons: Chichester, 1993. Goldenberg RL, Oliver SP, Bronstein J, Cutter GR, Andrews WW, Mennemeyer ST. Bed rest in pregnancy. Obstet Gynecol 1994; 84: 131–36.
Swedish in-vitro fertilisation study Sir—The Nov 6 commentary 1 by Nicholas Fisk and Geoffrey Trew and the article by T Bergh and colleagues in the same issue (p 1579)2 outline the risks associated with multiple pregnancy (especially triplets). This risk is associated with all multiple pregnancies and not just those created as a result of assisted conception. Both articles advocate a reduction in the number of embryos transferred to two or even one. The commentary maintains that the transfer of two embryos would not reduce the pregnancy rate. Furthermore, Templeton and Morris3 asserted that where more than four embryos were available for transfer (not two, as mentioned in the commentary) the live birth rate was not affected by the transfer of two or three embryos although there was a significant reduction in multiple pregnancy rate when two were transferred. This study has a major flaw because vital information that may affect the outcome, such as embryo quality, was not available to the investigators and the assumption is made that where two embryos are transferred, the embryo quality is similar to that in cases in which three embryos were transferred. In our clinic, which handles the largest number of in-vitro fertilsation (IVF) cycles in the UK, it is our policy to advise the transfer of two embryos either if more than four embryos are available in women younger than 38 years when the embryo quality is good, or if a patient will not consider fetal reduction should she have a triplet pregnancy. If the embryo quality is not good or is variable, if the patient has had repeated failed cycles in the past, or if the patient will consider fetal reduction should she have a triplet pregnancy, patients may opt for three embryos to be transferred. Frisk and Trew cite two controlled studies in which transfer of two
THE LANCET • Vol 355 • March 4, 2000