Longitudinal Analysis of Fev-1 Measurements by Asthmatic Patients In Comparison To Clinic Spirometry Measurements

Open Access
Author:
Moore, Amy Frances
Graduate Program:
Public Health Sciences
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 04, 2014
Committee Members:
  • Vernon Michael Chinchilli, Thesis Advisor
  • Lan Kong, Thesis Advisor
  • Kristen H Kjerulff, Thesis Advisor
Keywords:
  • FEV-1
  • Smoking Asthmatics
  • Longitudinal Analysis
  • Spirometery
  • Home-Monitoring of FEV-1
Abstract:
Background: Spirometry is considered to be the “gold standard” for assessing lung function in a clinical setting1. Researchers have studied at-home monitoring as an alternative to spirometry to offset inflating fiscal costs of medical monitoring, help patients adhere to their treatment regimen, and in some respects improve their quality of life. In addition, very few clinical have focused on asthmatics who are smokers. Objective: The objective of the research is to evaluate whether or not the FEV1 measurements taken at home are comparable to the spirometry performed in a clinical setting. Methods: The SMOG study data from all 44 nonsmokers and 39 light smokers will be obtained for evaluation. Of the original sample population, 34 non-smokers and 33 light smokers will be obtained for analysis. Linear mixed models will be conducted using the dependent variable, spirometry FEV1 measurements in a clinical setting. The independent variables will be the following: diary FEV1 measurements, age, height, weight, gender, race, and smoking history. Descriptive statistics were used to provide summary statistics of both dependent and independent variables. Concordance agreement and Pearson’s correlation will be used to evaluate diary card FEV1 measurements and spirometry FEV1 measurements in a clinical setting. Results: The Asthma Clinical Research Network conducted a study in asthmatics who smoke, called “Smoking Modulates Outcomes of Glucocortoid Therapy (SMOG).” The SMOG study had a mean age of 29.4 years (6.9). There were 34 females and 33 males. The overall average height was 67.3 inches (3.8). Overall, there were 15 (22.4%) Black (non-Hispanic Origin); 6 (9.0%) Hispanic; 6 (9.0%) Other; and 40 (59.7%) White (non-Hispanic Origin). The smoking status of the study population consisted of 33 (49.3%) smokers and 34 (50.7%) non-smokers. The average weight was 179 pounds (47.1). The linear mixed-effects model showed a statistically significance effect between the clinical spirometry FEV1 measurement and each of the following variables: the morning FEV1 diary measurement (p<0.0001); height (p<0.0001); gender (p=0.0116); Black (non-Hispanic Origin) race (p<0.0001); Hispanic race(p<0.0001); and the intercept (p=0.0378). The linear mixed-effects model without morning FEV1 diary measurement as a prognostic factor, showed a statistically significance effect between the clinical spirometry FEV1 measurement and the evening FEV1 diary measurement (p<0.0001). The linear mixed-effects model, without evening FEV1 diary as a prognostic factor, showed a statistically significance effect between the clinical spirometry FEV1 measurement and the morning FEV1 diary measurement (p<0.0001). The weighted and un-weighted Pearson’s Correlation Coefficient between the morning diary FEV1 and Clinical Spirometry FEV1 has a value of 0.81 (0.69, 0.89) and 0.81 (0.69, 0.89) respectively. The Concordance Agreement has a value of 0.66 (0.51, 0.76) and 0.66(0.51, 0.76), un-weighted and weighted, respectively between the morning diary FEV1 and the Clinical Spirometry FEV1. The weighted and un-weighted Pearson’s Correlation Coefficient between the evening diary FEV1 and Clinical Spirometry FEV1 has a value of 0.80 (0.67, 0.89) and 0.80 (0.68, 0.89) respectively. The Concordance Agreement has a value of 0.70 (0.55, 0.80) and 0.70 (0.55, 0.80), un-weighted and weighted, respectively between the morning diary FEV1 and the Clinical Spirometry FEV1. Conclusions: The morning FEV1 diary card was statistically significant within the linear mixed-effects model, suggesting that morning diary cards are significant predictors of spirometry in a clinical setting. The Pearson’s Correlation has shown a strong positive relationship between spirometry in a clinical setting and morning diary FEV1. . The Pearson’s Correlation also has shown a strong positive relationship between spirometry in a clinical setting and evening diary FEV1. The Concordance Agreement suggests a positive agreement with both the peak flowmeter measurements (morning or evening) and the spirometry in a clinical setting. We conclude that there is an agreement between the diary card measurements and clinical spirometry but further testing is required due to the weak to moderate relationship.