Pulmonary Abnormalities on High-Resolution CT Demonstrate More Rapid Decline Than FEV1 in Adults With Cystic Fibrosis: Longitudinal Measurements and Statistical Calculations

Pulmonary Abnormalities on High-Resolution CT Demonstrate More Rapid Decline Than FEV1 in Adults With Cystic Fibrosis: Longitudinal Measurements and Statistical CalculationsThe initial HRCT and spirometry findings obtained at time 1 are reported as HRCT-1 and PFT-1, and follow-up HRCT and spirometry findings obtained at time 2 are reported as HRCT-2 and PFT-2. Median time interval was 42 ± 16 months (range, 19 to 73 months). The annual rate of change in HRCT score (AHRCT) was calculated for each patient as follows: (HRCT-2 — HRCT-1)/individual time interval for each patient. A positive AHRCT value indicated a worsening in HRCT appearances. Similarly, the annual rate of change in PFT score (APFT) was calculated for each patient as follows: (PFT-2 — PFT-1)/individ-ual time interval for each patient. A negative APFT value indicated a worsening in spirometry results. http://www.medicines-for-diabetes.com/
The Wilcoxon signed-rank test was used to compare absolute numbers of patients for abnormalities between time 1 and time 2. Annual changes in composite CT, individual CT abnormalities, and PFTs were compared using repeated-measures analysis of variance, as described elsewhere. These comparisons were made for three separate groups: (1) all patients, (2) patients with mildly impaired lung function, and (3) patients with moderate-to-severely impaired lung function. Interobserver agreement for HRCT total scores was assessed using the intraclass correlation coefficient for total scores. A score > 0.8 is considered good agreement. Weighted к analysis was used to assess interobserver agreement for individual abnormalities. When the к value is 1.00, interobserver agreement is perfect; a value of zero indicates a level of agreement no better than chance. A value of 0.21 to 0.40 indicates fair agreement, 0.41 to 0.60 indicates moderate agreement, 0.61 to 0.80 indicates good agreement, and 0.81 to 1.00 indicates excellent agreement. Bland and Altman plots were utilized to evaluate for systematic bias between observers. Statistical significance was set at a p value < 0.05. Data are presented as mean ± SD.

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