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Left ventricular mass (LVM) is an in subsequent cardiovascular disease. assess the relationship between chi levels and IVM in children as dete YM

Left ventricular mass (LVM) is an in subsequent cardiovascular disease. assess the relationship between chi levels and IVM in children as dete YM

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Cardiovascular Disease, Pediatrics Left ventricular mass (LVM) is an important risk factor for subsequent cardiovascular disease. A study is proposed to assess the relationship between childhood blood pressure levels and LVM in children as determined from echocar- diograms. The goal is to stratify children into a normal bp group (< 80th percentile for their age, gender, and height) and an elevated bp group (≥ 90th percentile for their age, gender, and height) and compare change in LVM between the 2 groups. Before this can be done, one needs to dem- onstrate that LVM actually changes in children over a 4-year period. To help plan the main study, a pilot study is conducted where echocardiograms are obtained from 10 random chil- dren from the Bogalusa Heart Study at baseline and after 4 years of follow-up. The data are given in Table 7.6. 7.56 What test can be used to assess if there is a change in mean LVM over 4 years?
Transcribed Image Text:Cardiovascular Disease, Pediatrics Left ventricular mass (LVM) is an important risk factor for subsequent cardiovascular disease. A study is proposed to assess the relationship between childhood blood pressure levels and LVM in children as determined from echocar- diograms. The goal is to stratify children into a normal bp group (< 80th percentile for their age, gender, and height) and an elevated bp group (≥ 90th percentile for their age, gender, and height) and compare change in LVM between the 2 groups. Before this can be done, one needs to dem- onstrate that LVM actually changes in children over a 4-year period. To help plan the main study, a pilot study is conducted where echocardiograms are obtained from 10 random chil- dren from the Bogalusa Heart Study at baseline and after 4 years of follow-up. The data are given in Table 7.6. 7.56 What test can be used to assess if there is a change in mean LVM over 4 years?
TABLE 7.6 Pilot data on left ventricular mass (LVM) in children from the Bogalusa Heart Study 4-year LVM (g) Change (g)* ID 12345678 Baseline LVM (g) 9 10 Mean sd 139 134 86 98 78 90 163 126 142 96 111 108 167 24 -8 56 102 73 93 162 105.5 29.4 *4-year LVM minus baseline LVM 7.57 Implement the test in Problem 7.56 and provide a two-tailed p-value. 7.58 Provide a 95% CI for the change in LVM over 4 years based on the data in Table 7.6. 82 77 172 124.4 35.2 -2 33 18 65 9 -16 10 18.9 26.4 7.59 Since this was a pilot study, the main question of interest is how many subjects would be needed to detect an increase of 10 g in mean LVM over 4 years using a two- sided test with α = 0.05 and power = 80%? Hint: Assume that the estimated variance of change in LVM in the pilot study is the true variance of change in LVM.
Transcribed Image Text:TABLE 7.6 Pilot data on left ventricular mass (LVM) in children from the Bogalusa Heart Study 4-year LVM (g) Change (g)* ID 12345678 Baseline LVM (g) 9 10 Mean sd 139 134 86 98 78 90 163 126 142 96 111 108 167 24 -8 56 102 73 93 162 105.5 29.4 *4-year LVM minus baseline LVM 7.57 Implement the test in Problem 7.56 and provide a two-tailed p-value. 7.58 Provide a 95% CI for the change in LVM over 4 years based on the data in Table 7.6. 82 77 172 124.4 35.2 -2 33 18 65 9 -16 10 18.9 26.4 7.59 Since this was a pilot study, the main question of interest is how many subjects would be needed to detect an increase of 10 g in mean LVM over 4 years using a two- sided test with α = 0.05 and power = 80%? Hint: Assume that the estimated variance of change in LVM in the pilot study is the true variance of change in LVM.
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