This could mean that a patient with acceptable

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Unformatted text preview: ceptable initial scores fails to improve even if the improvement is obvious. Furthermore, a false negative response will be more likely when a patient perceives to having perfect functioning on a measure that only assesses severe dysfunction. The result confirms the importance of finding a quality of life instrument that does have a spectrum of dimensions which match the patients with chronic lower limb ischaemia related to the presence of numerous and often severe comorbid conditions. In this study the internal consistency was not as high as desirable for any of the instruments before revascularization, but both instruments exceeded the minimum internal consistency value of 0.7, except for social functioning in the SF-36 one year postoperatively. The SF-36, however, had considerably higher α-values in all other dimensions. Several studies have previously reported that the SF-36 has higher Cronbach's α values than the NHP, but the domains in which the highest and lowest values were estimated differ [37-40]. The findings suggest that it is not only the magnitude of the correlation among items, but also the number of items in the scale that affects the internal consistency. For example, the domains of pain and social functioning in the NHP contain 8 and 5 items Page 7 of 11 (page number not for citation purposes) Health and Quality of Life Outcomes 2004, 2 http://www.hqlo.com/content/2/1/9 100 80 60 40 20 0 BP * PF MH VT SF ** Claudicants (n=38) BP ** PF MH VT SF Critical ischaemia (n=28) Figure 2in median score for the SF-36 in claudicants and critical ischaemia patients before and one year after revascularization Changes Changes in median score for the SF-36 in claudicants and critical ischaemia patients before and one year after revascularization. Tested by Wilcoxon Signed Ranks test. A higher score indicates fewer perceived problems. BP = Bodily pain, PF = Physical functioning, MH = Mental health, VT = Vitality and SF = Social functioning. Page 8 of 11 (page number not for citation purposes) Health and Quality of Life Outcomes 2004, 2 http://www.hqlo.com/content/2/1/9 100 80 60 40 20 0 P PM EM E Claudicants (n=38) SO P ** PM EM E SO ** Critical ischaemia (n=28) Figure Changes3in median score for the NHP in claudicants and critical ischaemia patients before and one year after revascularization Changes in median score for the NHP in claudicants and critical ischaemia patients before and one year after revascularization. Tested by Wilcoxon Signed Ranks test. A higher score indicates more perceived problems. P = Pain, PM = Physical mobility, EM = Emotional reactions, E = Energy and SO = Social isolation. Page 9 of 11 (page number not for citation purposes) Health and Quality of Life Outcomes 2004, 2 respectively, while bodily pain and social functioning in the SF-36 contain only 2 items. This is further strengthened by the fact that both the scales were not sensitive enough to identify significant within-patients changes in social isolation and social functioning. Another explanation could be that the patients were a more homogeneous...
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This document was uploaded on 11/24/2013.

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