Quality of the evidence
The causes of falls in people after stroke are complex, and a trial aimed at preventing falls requires a complex intervention. We assessed the majority of trials included in this review as having a low risk of selection, attrition and reporting biases, as well as a reliable ascertainment of falls/fallers outcome (see Figure 3). Of concern was the level of detection bias (blinding of outcome assessment for falls). In the majority of trials (80%), we assessed this as being at high risk of bias, as studies used a self reported questionnaire or a falls calendar or diary. These methods rely on active registration by the participant, with telephone calls to the participants if (monthly) fall calendars are not returned. Never the less, we assessed this as being at high risk of bias, since the assessors, who were in this case the participants themselves, were probably not blinded to group allocation, and because the accuracy of prospective reporting methods may lead to over-or under-reporting of falls (Lamb 2005). Kunkel 2011, comparing retrospective interviews and prospective falls diaries over a 12-month period in a cohort of 122 people with stroke, found an 83% agreement between the methods in the classification of fallers. Yet frequent repeat fallers reported falls during the retrospective interview but did not record all falls in the diary. Excluding these outliers, a similar number of falls were reported using either method. Our results for detection bias and the findings from Kunkel 2011 indicate that monitoring falls accurately in a chronic, community-dwelling population remains difficult. Although prospective methods are considered preferable (Hauer 2006), future trials could include both retrospective and prospective methods. Never the less, preliminary studies investigating novel assessments of falls,such as portable activity monitors, seem warranted for future research. Another concern arising from the trials included in this review is the definition of falls. Of the 10 trials, only seven provided a definition of a fall and, among these five different definitions were used, with two trials (Sato 2005a; Sato 2011) presenting a definition not referenced to previous literature. Although the content of these different definitions might not be significantly different, uniformity should be sought in future trials evaluating interventions for preventing falls in people after stroke, with a consensual definition of a fall, such as the one developed by the Preventions of Falls Network Europe (Lamb 2005). Finally,for six out of 10 trials,the primary aim was to prevent falls. For five of the six,a power calculation was also performed based on establishing reduction in falls/fallers. The single aim of Holmgren 2010 was to prevent falls, but the power calculation was based on finding an increase in the Berg Balance Scale score, leading to a total of 34 participants recruited. The non significant finding for falls and fallers may have resulted from an inadequate sample size for this outcome. Unpublished stroke subgroup results from Haran 2010 should also be interpreted with caution; this analysis is underpowered, since a limited group of the total study sample was selected for our analysis. Future trials need to be of adequate size, with a power calculation based on reasonable estimates of
คุณภาพของหลักฐานThe causes of falls in people after stroke are complex, and a trial aimed at preventing falls requires a complex intervention. We assessed the majority of trials included in this review as having a low risk of selection, attrition and reporting biases, as well as a reliable ascertainment of falls/fallers outcome (see Figure 3). Of concern was the level of detection bias (blinding of outcome assessment for falls). In the majority of trials (80%), we assessed this as being at high risk of bias, as studies used a self reported questionnaire or a falls calendar or diary. These methods rely on active registration by the participant, with telephone calls to the participants if (monthly) fall calendars are not returned. Never the less, we assessed this as being at high risk of bias, since the assessors, who were in this case the participants themselves, were probably not blinded to group allocation, and because the accuracy of prospective reporting methods may lead to over-or under-reporting of falls (Lamb 2005). Kunkel 2011, comparing retrospective interviews and prospective falls diaries over a 12-month period in a cohort of 122 people with stroke, found an 83% agreement between the methods in the classification of fallers. Yet frequent repeat fallers reported falls during the retrospective interview but did not record all falls in the diary. Excluding these outliers, a similar number of falls were reported using either method. Our results for detection bias and the findings from Kunkel 2011 indicate that monitoring falls accurately in a chronic, community-dwelling population remains difficult. Although prospective methods are considered preferable (Hauer 2006), future trials could include both retrospective and prospective methods. Never the less, preliminary studies investigating novel assessments of falls,such as portable activity monitors, seem warranted for future research. Another concern arising from the trials included in this review is the definition of falls. Of the 10 trials, only seven provided a definition of a fall and, among these five different definitions were used, with two trials (Sato 2005a; Sato 2011) presenting a definition not referenced to previous literature. Although the content of these different definitions might not be significantly different, uniformity should be sought in future trials evaluating interventions for preventing falls in people after stroke, with a consensual definition of a fall, such as the one developed by the Preventions of Falls Network Europe (Lamb 2005). Finally,for six out of 10 trials,the primary aim was to prevent falls. For five of the six,a power calculation was also performed based on establishing reduction in falls/fallers. The single aim of Holmgren 2010 was to prevent falls, but the power calculation was based on finding an increase in the Berg Balance Scale score, leading to a total of 34 participants recruited. The non significant finding for falls and fallers may have resulted from an inadequate sample size for this outcome. Unpublished stroke subgroup results from Haran 2010 should also be interpreted with caution; this analysis is underpowered, since a limited group of the total study sample was selected for our analysis. Future trials need to be of adequate size, with a power calculation based on reasonable estimates of
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