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?
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?
MATLAB: An Introduction with Applications
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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 echocardiograms. 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 demonstrate 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 children 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:**Table 7.6: Pilot Data on Left Ventricular Mass (LVM) in Children from the Bogalusa Heart Study**
This table provides data from a pilot study focusing on the left ventricular mass (LVM) in children, measured in grams (g). Measurements were taken at baseline and after 4 years.
| ID | Baseline LVM (g) | 4-year LVM (g) | Change (g)* |
|-----|------------------|----------------|------------|
| 1 | 139 | 163 | 24 |
| 2 | 134 | 126 | -8 |
| 3 | 86 | 142 | 56 |
| 4 | 98 | 96 | -2 |
| 5 | 78 | 111 | 33 |
| 6 | 90 | 108 | 18 |
| 7 | 102 | 167 | 65 |
| 8 | 73 | 82 | 9 |
| 9 | 93 | 77 | -16 |
| 10 | 162 | 172 | 10 |
**Mean**: Baseline LVM = 105.5 g; 4-Year LVM = 124.4 g; Change = 18.9 g
**Standard Deviation (sd)**: Baseline LVM = 29.4 g; 4-Year LVM = 35.2 g; Change = 26.4 g
*The change column represents the 4-year LVM minus the baseline LVM.
**Discussion Points:**
7.57. **Statistical Test**: Implement the test in Problem 7.56 and provide a two-tailed p-value.
7.58. **Confidence Interval**: Provide a 95% confidence interval for the change in LVM over 4 years based on the data in Table 7.6.
7.59. **Study Planning**: Since this was a pilot study, determine 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 the estimated variance of change in
Expert Solution
Step 1
A sample data of 10 children was taken. Therefore, sample size n = 10
The baseline LVM and 4-years LVM were recorded for each of these 10 children.
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