Correlação entre qualidade de vida e a fração exalada do óxido nítrico em crianças e adolescentes com asma

Abstract

Objective: The sequential assessment of quality of life and exhaled nitric oxide (FeNO) could help in the monitoring of asthmatic patients. However, few studies examining the correlation between these variables. The aim of this study is to assess the correlation between a score of quality of life and exhaled nitric oxide in children and adolescents with asthma not controlled or partially controlled. Methods: We conducted a cross-sectional study in the Pediatric Pulmonology Outpatient Clinic of Hospital das Clínicas of the Federal University of Minas Gerais (Belo Horizonte, Brazil) between August 2008 and August 2010, involving patients between six and eighteen years of age with asthma not controlled or partially controlled on inhaled corticosteroid treatment in doses equal or equivalent to 500 mcg of beclomethasone. The diagnosis and classification of asthma were made according to the Global Initiative for Asthma. The patients answered the Questionnaire Quality of Life in Pediatric Asthma (QVAP), proposed by Juniper. We used a scoring system with scores ranging from one to seven points. One point means the most impact on quality of life and seven points indicates no damage. Values less than or equal four are indicative of moderate impairment of quality of life. The measurement of exhaled nitric oxide was performed according to the criteria of the American Thoracic Society. The upper limits of normal FeNO are 15 ppb for children four years, with an average increase of one ppb and 25 ppb per year for teens. The equipment used was NIOX MINO ® (Aerocrine, Sweden). To calculate the correlation we used the Pearson correlation coefficient. Results: Forty three patients were enrolled. The mean age was 11,67 years. Twenty- seven (32,9%) were male. The average score of QVAP was 4.99 points (ranging from 2.09 to 6.78 points), whereas the mean FeNO was 41,06 ppb (range 8 a 179 ppb). There was no statistically significant correlation between FeNO and QVAP (Pearson r = 0.136, p = 0.384). Conclusion: Mean FeNO was higher compared to expected values for different age groups, which corroborates with the fact that asthma is not controlled. Moreover, the average score of the questionnaires was also high, indicating no impairment of quality of life, despite the lack of control of asthma. The lack of correlation between these variables indicates that they behave differently, probably because they evaluate different aspects of the disease.