PubMed · 15539752
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Colin Borland. 2004. Nitric oxide diffusing capacity on exercise.. https://doi.org/10.1378/chest.126.5.1708-a
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INTRODUCTION: The 6-min walk test (6MWT) has prognostic value in various pulmonary disorders including idiopathic pulmonary fibrosis (IPF). We determined the individual prognostic accuracy of distance walked and oxygen saturation during the 6MWT in patients with IPF. We defined a new composite index, the distance-saturation product (DSP), which is the product of distance walked and lowest oxygen saturation during the 6-min walk test. We compared the performance of the DSP to the individual 6MWT parameters in predicting mortality. METHODS: We evaluated pulmonary function tests, 6-min walk parameters and the DSP between survivors and non-survivors. The ability of each measure to discriminate outcomes was determined by receiver operator curves. RESULTS: 81 patients (48 survivors, 33 non-survivors) were included. Pulmonary function tests were similar and did not correlate with survival. Desaturation was greater (89.4% versus 83.7%, P<0.001) and distance walked was lower (406.9 versus 181.3m, P = 0.005) in non-survivors. The DSP was significantly lower among non-survivors (364.8 versus 153.5m%, P < 0.001) and predicted mortality more accurately than either individual 6MWT component (P = 0.035 versus desaturation, P=0.040 versus distance). A DSP <200 m% was associated with a seven-fold greater risk of 12-month mortality and an 18.0% shorter median survival compared with a DSP > 200 m% (P < 0.001). DISCUSSION: Each component of the 6-min walk independently predicted mortality in IPF with greater accuracy than spirometry. However, a composite of both parameters, the DSP, provides slightly greater accuracy and represents a novel measure for assessing survival in patients with IPF.
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OBJECTIVE: To systematically review the measurement properties (i.e. internal consistency, reproducibility, validity, responsiveness and interpretability) of all performance-based methods which have been used to measure the physical function of patients with osteoarthritis of the hip or knee. METHODS: A systematic search was conducted in Medline, CINAHL, PsychINFO and Embase. Standardized criteria were applied to assess the quality of the clinimetric studies and the measurement properties. RESULTS: Twenty-six performance-based methods were included: 13 walking tests, two stair-climb tests, one chair test and ten multi-item tests. Three out of seven multi-activity tests were tested for internal consistency and two were rated positively. Fourteen tests were tested for reliability and five were rated positively. The absolute measurement error (agreement) was assessed for 10 tests. Only one test received a positive rating. Fourteen tests were tested for construct validity. Only two tests received positive ratings. Responsiveness was assessed for 12 tests, but none of them received a positive rating. A lot of indeterminate ratings were given, mostly for small studies or non-optimal analyses. CONCLUSION: Many more well-designed studies are needed to assess the measurement properties of performance-based methods. More importantly, however, before one can make a justified choice of a particular performance-based method, consensus is needed on what activities should be included in a performance-based test for patients with hip or knee osteoarthritis and which aspects of function should be measured.