Objective: To analyze adolescents clinically diagnosed with asthma, in terms of the physiological changes occurring during acute hypoxia and during a maximal stress test. Methods: This was a descriptive, cross-sectional study involving 48 adolescents (12-14 years of age) who were divided into three groups: mild intermittent asthma (MIA, n = 12); mild persistent asthma (MPA, n = 12); and control (n = 24). All subjects were induced to acute hypoxia and were submitted to maximal stress testing. Anthropometric data were collected, and functional variables were assessed before and after the maximal stress test. During acute hypoxia, the time to a decrease in SpO2 and the time to recovery of SpO2 (at rest) were determined. Results: No significant differences were found among the groups regarding the anthropometric variables or regarding the ventilatory variables during the stress test. Significant differences were found in oxygen half-saturation pressure of hemoglobin prior to the test and in PaO2 prior to the test between the MPA and control groups (p = 0.0279 and p = 0.0116, respectively), as was in the oxygen extraction tension prior to the test between the MIA and MPA groups (p = 0.0419). There were no significant differences in terms of the SpO2 times under any of the conditions studied. Oxygen consumption and respiratory efficiency were similar among the groups. The use of a bronchodilator provided no significant benefit during the hypoxia test. No correlations were found between the hypoxia test results and the physiological variables. Conclusions: Our findings suggest that adolescents with mild persistent asthma have a greater capacity to adapt to hypoxia than do those with other types of asthma.

Keywords: Asthma; Adolescent; Cell hypoxia; Exercise test.

Objective: To assess children and adolescents diagnosed with mild intermittent or mild persistent asthma, in terms of their aerobic capacity between attacks. Methods: We included 33 children and adolescents recently diagnosed with asthma (mild intermittent or mild persistent) and 36 healthy children and adolescents. Those with asthma were evaluated between attacks. All participants underwent clinical evaluation; assessment of baseline physical activity level; pre- and post-bronchodilator spirometry; and a maximal exercise test, including determination of maximal voluntary ventilation, maximal oxygen uptake, respiratory quotient, maximal minute ventilation, ventilatory equivalent, ventilatory reserve, maximal HR, SpO2, and serum lactate. Results: No significant differences were found among the groups (intermittent asthma, persistent asthma, and control) regarding anthropometric or spirometric variables. There were no significant differences among the groups regarding the variables studied during the maximal exercise test. Conclusions: A diagnosis of mild intermittent/persistent asthma has no effect on the aerobic capacity of children and adolescents between asthma attacks.

Keywords: : Asthma; Exercise; Respiratory function tests.

Objective: To infer the prevalence and variables predictive of isolated nocturnal hypoxemia and obstructive sleep apnea (OSA) in patients with COPD and mild hypoxemia. Methods: This was a cross-sectional study involving clinically stable COPD outpatients with mild hypoxemia (oxygen saturation = 90-94%) at a clinical center specializing in respiratory diseases, located in the city of Goiânia, Brazil. The patients underwent clinical evaluation, spirometry, polysomnography, echocardiography, arterial blood gas analysis, six-minute walk test assessment, and chest X-ray. Results: The sample included 64 patients with COPD and mild hypoxemia; 39 (61%) were diagnosed with sleep-disordered breathing (OSA, in 14; and isolated nocturnal hypoxemia, in 25). Correlation analysis showed that PaO2 correlated moderately with mean sleep oxygen saturation (r = 0.45; p = 0.0002), mean rapid eye movement (REM) sleep oxygen saturation (r = 0.43; p = 0.001), and mean non-REM sleep oxygen saturation (r = 0.42; p = 0.001). A cut-off point of PaO2 ≤ 70 mmHg in the arterial blood gas analysis was significantly associated with sleep-disordered breathing (OR = 4.59; 95% CI: 1.54-13.67; p = 0.01). The model showed that, for identifying sleep-disordered breathing, the cut-off point had a specificity of 73.9% (95% CI: 51.6-89.8%), a sensitivity of 63.4% (95% CI: 46.9-77.9%), a positive predictive value of 81.3% (95% CI: 67.7-90.0%), and a negative predictive value of 53.1% (95% CI: 41.4-64.4%), with an area under the ROC curve of 0.69 (95% CI: 0.57-0.80), correctly classifying the observations in 67.2% of the cases. Conclusions: In our sample of patients with COPD and mild hypoxemia, the prevalence of sleep-disordered breathing was high (61%), suggesting that such patients would benefit from sleep studies.

Keywords: Pulmonary disease, chronic obstructive/complications; Sleep wake disorders/epidemiology; Anoxia/etiology.

Objective: Asthma is the most common chronic pulmonary disease, characterized by bronchial inflammation. Some children with asthma have persistent pulmonary function impairment. The prevalence and etiology of this abnormality in children with asthma in developing countries remain unknown. The objective of this study was to estimate the proportion of patients with impaired pulmonary function who were unresponsive to treatment in a group of children and adolescents with asthma, and to describe the phenotypic characteristics of the sample. Methods: Using a standardized questionnaire, we selected outpatients (5-17 years of age) diagnosed with persistent asthma. These patients underwent spirometry and skin prick tests for sensitivity to common aeroallergens. Persistent pulmonary function impairment was defined as an FEV1/FVC ratio < 0.80, even after 10 days of treatment with bronchodilators and oral corticosteroids. We used the atopic index to differentiate between patients with little or no response to the skin prick test and those with a strong response (cut-off point: 4 allergens). Results: We included 96 patients with a mean age of 10.6 years. Of those, 52 (54.1%) were male, and 89 (92.7%) were atopic. Of the 96 patients, 8 (8.3%) had impaired pulmonary function even after the treatment. Among those patients, 8 (100%) were atopic, 7 (87.5%) had moderate or severe asthma, and 7 (87.5%) had a history of hospitalization for acute bronchiolitis. Conclusions: Children and adolescents with moderate or severe asthma can present with impaired pulmonary function and be unresponsive to treatment. This clinical situation has been little studied in developing countries, and its risk factors and etiology will be better understood only through birth cohort studies.

Keywords: Asthma; Respiratory function tests; Allergy and immunology.

Objectives: To compare clinical and radiological aspects, as well as aspects regarding the course of the disease, of elderly inpatients clinically diagnosed with community-acquired pneumonia, with or without radiological confirmation. Methods: A total of 141 patients over the age of 60 were retrospectively studied. Results: Radiological findings corroborated the clinical diagnosis in 45 patients, whereas, in 96 patients, radiology did not correlate with the clinical suspicion. The signs, symptoms, treatment, and outcomes of these two groups were compared. The findings of the study suggest that there were no significant differences between the groups according to the criteria analyzed. Conclusion: The prevalence of chest X-rays compatible with pneumonia in patients suspected of the disease was slightly higher than 30%. Having low specificity in the elderly, the clinical diagnosis of community-acquired pneumonia should be used with caution. In view of the small number of patients studied, further studies on this topic are needed in order to confirm the findings.

Keywords: Pneumonia; Aged; Diagnosis; Radiology; Hospitalization.

Objective: To evaluate the diagnostic contribution of molecular analysis of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in patients suspected of having mild or atypical cystic fibrosis (CF). Methods: This was a cross-sectional study involving adolescents and adults aged ≥ 14 years. Volunteers underwent clinical, laboratory, and radiological evaluation, as well as spirometry, sputum microbiology, liver ultrasound, sweat tests, and molecular analysis of the CFTR gene. We then divided the patients into three groups by the number of mutations identified (none, one, and two or more) and compared those groups in terms of their characteristics. Results: We evaluated 37 patients with phenotypic findings of CF, with or without sweat test confirmation. The mean age of the patients was 32.5 ± 13.6 years, and females predominated (75.7%). The molecular analysis contributed to the definitive diagnosis of CF in 3 patients (8.1%), all of whom had at least two mutations. There were 7 patients (18.9%) with only one mutation and 26 patients (70.3%) with no mutations. None of the clinical characteristics evaluated was found to be associated with the genetic diagnosis. The most common mutation was p.F508del, which was found in 5 patients. The combination of p.V232D and p.F508del was found in 2 patients. Other mutations identified were p.A559T, p.D1152H, p.T1057A, p.I148T, p.V754M, p.P1290P, p.R1066H, and p.T351S. Conclusions: The molecular analysis of the CFTR gene coding region showed a limited contribution to the diagnostic investigation of patients suspected of having mild or atypical CF. In addition, there were no associations between the clinical characteristics and the genetic diagnosis.

Objective: There are many ways of assessing sleepiness, which has many dimensions. In patients presenting a borderline apnea-hypopnea index (AHI, expressed as events/hour of sleep), the mechanisms of excessive daytime sleepiness (EDS) remain only partially understood. In the initial stages of sleep-disordered breathing, the AHI might be related to as-yet-unexplored EDS dimensions. Methods: We reviewed the polysomnography results of 331 patients (52% males). The mean age was 40 ± 13 years, and the mean AHI was 4 ± 2 (range, 0-9). We assessed ten potential dimensions of sleepiness based on polysomnography results and medical histories. Results: The AHI in non-rapid eye movement (NREM) stage 1 sleep (AHI-N1), in NREM stage 2 sleep (AHI-N2), and in REM sleep (AHI-REM) were, respectively, 6 ± 7, 3 ± 3 and 10 ± 4. The AHI-N2 correlated significantly with the greatest number of EDS dimensions (5/10), including the Epworth sleepiness scale score (r = 0.216, p < 0.001). Factor analysis, using Cronbach's alpha, reduced the variables to three relevant factors: QUESTIONNAIRE (α = 0.7); POLYSOMNOGRAPHY (α = 0.68); and COMPLAINTS (α = 0.55). We used these factors as dependent variables in a stepwise multiple regression analysis, adjusting for age, gender, and body mass index. The AHI-N1 correlated significantly with POLYSOMNOGRAPHY (β = −0.173, p = 0.003), and the AHI-N2 correlated significantly with COMPLAINTS (β = −0.152, p = 0.017). The AHI-REM did not correlate with any factor. Conclusions: Our results underscore the multidimensionality of EDS in mild sleep apnea.

Keywords: Disorders of excessive somnolence; Sleep apnea syndromes; Sleep, REM; Polysomnography.

Obstructive sleep apnea (OSA) has been associated with oxidative stress and various cardiovascular consequences, such as increased cardiovascular disease risk. Quantitative real-time PCR is frequently employed to assess changes in gene expression in experimental models. In this study, we analyzed the effects of chronic intermittent hypoxia (an experimental model of OSA) on housekeeping gene expression in the left cardiac ventricle of rats. Analyses via four different approaches-use of the geNorm, BestKeeper, and NormFinder algorithms; and 2−ΔCt (threshold cycle) data analysis-produced similar results: all genes were found to be suitable for use, glyceraldehyde-3-phosphate dehydrogenase and 18S being classified as the most and the least stable, respectively. The use of more than one housekeeping gene is strongly advised.

Keywords: Cell hypoxia; Reference standards; Sleep apnea, obstructive; Cardiovascular diseases; Models, animal; Polymerase chain reaction.

Objective: To evaluate quality of sleep and pulmonary function in clinically stable adolescents with sickle cell anemia (SCA). Methods: A cross-sectional descriptive study involving 50 patients with SCA submitted to nocturnal polysomnography and spirometry at the Brasília University Hospital. Anthropometric, polysomnographic and pulmonary function data were analyzed. Patients were divided into two groups according to oxygen saturation by pulse oximetry (SpO2) during rapid eye movement (REM) sleep: SpO2 ≤ 93%; and SpO2 > 93%. Descriptive statistics, Student's t-test, chi-square test and Pearson's correlation coefficient were used. Results: Mean age was 13.9 ± 2.5 years. Total sleep time and REM sleep percentage were lower, whereas REM sleep latency, the number of awakenings, movement during sleep, changes in sleep stage, sleep-disordered breathing index and obstructive apnea index were higher. Two patients (4%) did not present REM. There were statistically significant differences between the groups in most of the polysomnographic variables. The SpO2 in REM sleep presented a strong positive correlation with waking SpO2 and with SpO2 in non-REM sleep, whereas it presented a strong negative correlation with the percentage of total sleep time during which SPO2 was < 90%. Mean spirometric values were within normal ranges. Residual volume and the residual volume/total lung capacity/functional residual capacity ratio were elevated. Conclusion: Sleep impairment in clinically stable patients with SCA is probably due to hemoglobin desaturation and not to individual alterations in pulmonary function.

Keywords: Sleep disorders; Polysomnography; Adolescent; Anemia, sickle cell; Spirometry.

Objective: Chloroquine or hydroxychloroquine has demonstrated no effect on the treatment of hospitalized COVID-19 patients. This study aimed to answer questions related to the use of hydroxychloroquine for pre-exposure or post-exposure prophylaxis of SARS-CoV-2 infection and in the treatment of patients with mild COVID-19 in terms of hospitalization, adverse events, and mortality. Methods: This was a systematic review and meta-analysis of phase 3 randomized clinical trials, selected from various databases, which compared patients who received hydroxychloroquine for SARS-CoV-2 prophylaxis or treatment of mild COVID-19 cases with controls. Results: A total number of 1,376 studies were retrieved. Of those, 9 met the eligibility criteria and were included in the study. No statistically significant differences were found between the hydroxychloroquine and control groups in terms of pre- or post-exposure prophylaxis of SARS-CoV-2 infection. The use of hydroxychloroquine increased the risk of adverse events by 12% (95% CI, 6-18%; p < 0.001), and the number needed to harm was 9. In addition, no significant differences were found between the hydroxychloroquine and control groups regarding hospitalization (risk difference [RD] = -0.02; 95% CI, -0.04 to 0.00; p = 0.14) or mortality (RD = 0.00; 95% CI, -0.01 to 0.02; p = 0.98) in the treatment of mild COVID-19. Conclusions: The use of hydroxychloroquine for prophylaxis of SARS-CoV-2 infection or treatment of patients with mild COVID-19 is not recommended.

Keywords: Hydroxychloroquine; COVID-19; SARS-CoV-2.

To evaluate the characteristics of users of inhalers and the frequency of inhaler use among adolescents and adults with self-reported physician-diagnosed asthma, bronchitis, or emphysema. Methods: A population-based study conducted in the city of Pelotas, Brazil, involving 3,670 subjects ≥ 10 years of age, evaluated with a questionnaire. Results: Approximately 10% of the sample reported at least one of the respiratory diseases studied. Among those individuals, 59% reported respiratory symptoms in the last year, and, of those, only half reported using inhalers. The use of inhalers differed significantly by socioeconomic status (39% and 61% for the lowest and the highest, respectively, p = 0.01). The frequency of inhaler use did not differ by gender or age. Among the individuals reporting emphysema and inhaler use, the use of the bronchodilator-corticosteroid combination was more common than was that of a bronchodilator alone. Only among the individuals reporting physician-diagnosed asthma and current symptoms was the proportion of inhaler users higher than 50%. Conclusions: In our sample, inhalers were underutilized, and the type of medication used by the individuals who reported emphysema does not seem to be in accordance with the consensus recommendations.

Keywords: Metered dose inhalers; Asthma; Pulmonary disease, chronic obstructive; Bronchitis; Emphysema; Dry powder inhalers.

Objective: To determine the prevalence of smoking experimentation among adolescents with asthma or allergic rhinitis. Methods: This was a cross-sectional study involving adolescent students (13-14 years of age) in the city of Belo Horizonte, Brazil. The participants completed the Centers for Disease Control and Prevention and International Study of Asthma and Allergies in Childhood questionnaires, both of which have been validated for use in Brazil. We calculated the prevalence of smoking experimentation in the sample as a whole, among the students with asthma symptoms, and among the students with allergic rhinitis symptoms, as well as in subgroups according to gender and age at smoking experimentation. Results: The sample comprised 3,325 adolescent students. No statistically significant differences were found regarding gender or age. In the sample as a whole, the prevalence of smoking experimentation was 9.6%. The mean age for smoking experimentation for the first time was 11.1 years of age (range, 5-14 years). Among the adolescents with asthma symptoms and among those with allergic rhinitis symptoms, the prevalence of self-reported smoking experimentation was 13.5% and 10.6%, respectively. Conclusions: The proportion of adolescents with symptoms of asthma or allergic rhinitis who reported smoking experimentation is a cause for concern, because there is strong evidence that active smoking is a risk factor for the occurrence and increased severity of allergic diseases.

Keywords: Asthma/epidemiology; Rhinitis/epidemiology; Smoking/epidemiology.

Objectives: To describe persistent symptoms and lung function in mild cases of COVID-19 six months after infection. Methods: Data collection was performed through a semi-structured questionnaire containing information on the participants' demographic and anthropometric data, the disease in the acute phase, and persistent symptoms six months after COVID-19 using spirometry and manovacuometry. Results: A total of 136 participants were evaluated, of whom 64% were male, with a mean age of 38.17 ± 14.08 years and a body mass index (BMI) of 29.71 ± 17.48 kg/m2. The main persistent symptoms reported were dyspnea on exertion (39.7%), memory loss (38.2%), and anxiety (48.5%). Considering lung function, the participants reached 88.87 ± 17.20% of the predicted forced vital capacity (FVC), 86.03 ± 22.01% of the forced expiratory volume in one second (FEV1), and 62.71 ± 25.04% of peak expiratory flow (PEF). Upon manovacuometry, 97.41 ± 34.67% of the predicted inspiratory force (Pimax) and 66.86 ± 22.97% of the predicted expiratory force (Pemax) were observed. Conclusions: Six months after COVID-19 infection, a reduction in PEF and MEP was observed. Among the most commonly reported persistent symptoms were fatigue, tiredness with the slightest exertion, anxiety and depression, memory loss, and deficits in concentration.

Keywords: Post-acute COVID-19 Syndrome, Respiratory Function Tests, Dyspnea.

Objective: In view of the current COVID-19 pandemic, the objective of this study was to determine, through a systematic review and meta-analysis, whether the use of N95/FFP2 masks during aerobic exercise has a significant impact on HR, RR, SpO2, and blood pressure (BP) in healthy individuals. Methods: We searched the MEDLINE database for studies published in English between 2005 and 2021. To reduce bias and increase reliability, only randomized controlled trials and randomized crossover clinical trials were considered for inclusion. The selected outcomes included HR, RR, SpO2, and BP, with perceived exertion being evaluated by means of the Borg scale. Results: Eight controlled trials were included in the meta-analysis. Seven evaluated HR (p > 0.05), five evaluated RR (p > 0.05), five evaluated SpO2 and BP (p > 0.05 for both), and six evaluated perceived exertion, presenting controversial results such as risk ratios that were grouped for each variable. Conclusions: This study suggests that N95 and FFP2 masks do not have significant effects on HR, RR, SpO2, and BP during aerobic exercise in healthy individuals.

Keywords: N95 respirators; Heart rate; Respiratory rate; Oxygen saturation; Blood.

Objective: Fluticasone and formoterol are effective in the treatment of asthma. When a corticosteroid alone fails to control asthma, combination therapy is the treatment of choice. The objective of this study was to compare the efficacy and safety of formulations containing budesonide/formoterol (BUD/FOR), fluticasone alone (FLU), and the single-capsule combination of fluticasone/formoterol (FLU/FOR) on lung function in patients with mild-to-moderate persistent asthma. Methods: This was a randomized, multicenter, open phase III trial conducted in Brazil. The primary efficacy analysis was the assessment of non-inferiority between FLU/FOR and BUD/FOR combinations regarding FEV1 (in L) at the final visit. The secondary analyses were PEF, level of asthma control, serum cortisol levels, frequency of adverse events, adherence to treatment, and appropriate inhaler use. Results: We randomized 243 patients to three groups: FLU/FOR (n = 79), BUD/FOR (n = 83), and FLU (n = 81). In terms of the mean FEV1 after 12 weeks of treatment, the difference between the FLU/FOR and BUD/FOR groups was 0.22 L (95% CI: −0.06 to 0.49), whereas the difference between the FLU/FOR and FLU groups was 0.26 L (95% CI: −0.002 to 0.52). Non-inferiority was demonstrated by the difference between the lower limits of the two 95% CIs (−0.06 vs. −0.002). The level of asthma control and PEF were significantly greater in the FLU/FOR and BUD/FOR groups than in the FLU group. There were no significant differences among the groups regarding patient adherence, patient inhaler use, or safety profile of the formulations. Conclusions: The single-capsule combination of FLU/FOR showed non-inferiority to the BUD/FOR and FLU formulations regarding efficacy and safety, making it a new treatment option for persistent asthma. (ClinicalTrials.gov Identifier:NCT01202084 [http://www.clinicaltrials.gov/])

Keywords: Asthma; Steroids; Bronchodilator agents; Administration, inhalation.

Objective: There is an indirect relationship between airway obstruction in asthma and the intensity of breathlessness (dyspnea). A word labeled visual analog dyspnea scale with a 0-3 score has been widely used for the assessment of the degree of bronchoconstriction, although the perception of such obstruction varies considerably. The objective of this study was to determine whether children and adolescents are able to perceive acute exercise-induced bronchoconstriction (EIB), as well as to measure the discriminatory power of a word labeled visual analog dyspnea scale in relation to the intensity of the EIB. Methods: A cross-sectional study involving 134 children and adolescents with asthma and submitted to a six-minute steady-state exercise test on a cycle ergometer. The intensity of dyspnea was determined using a word labeled visual analog dyspnea scale prior to each determination of FEV1. The scale is scored from 0 to 3, with a logical sequence of pictures, ranging from "no symptoms" to "severe dyspnea". Variables were determined at baseline, as well as at 5, 10, and 20 min after the exercise test. The accuracy of the dyspnea scale in identifying the degree of EIB was determined by means of ROC curves for the post-exercise fall in FEV1, using cut-off points of 10%, 20%, 30%, and 40%. Results: Of the patients selected, 111 finished the study, and 52 (46.8%) presented with EIB. The area under the ROC curve increased in direct proportion to increases in the degree of bronchoconstriction. Conclusions: Among children and adolescents with asthma, the accuracy of this dyspnea scale improves as the post-exercise percentage fall in FEV1 increases. However, the predictive value of the scale is suboptimal when the percentage fall in FEV1 is lower.

Keywords: Asthma; Asthma, exercise-induced; Dyspnea.

Objective: To investigate the effect of intermittent hypoxia-a model of obstructive sleep apnea (OSA)-on pancreatic expression of uncoupling protein-2 (UCP2), as well as on glycemic and lipid profiles, in C57BL mice. Methods: For 8 h/day over a 35-day period, male C57BL mice were exposed to intermittent hypoxia (hypoxia group) or to a sham procedure (normoxia group). The intermittent hypoxia condition involved exposing mice to an atmosphere of 92% N and 8% CO2 for 30 s, progressively reducing the fraction of inspired oxygen to 8 ± 1%, after which they were exposed to room air for 30 s and the cycle was repeated (480 cycles over the 8-h experimental period). Pancreases were dissected to isolate the islets. Real-time PCR was performed with TaqMan assays. Results: Expression of UCP2 mRNA in pancreatic islets was 20% higher in the normoxia group than in the hypoxia group (p = 0.11). Fasting serum insulin was higher in the hypoxia group than in the normoxia group (p = 0.01). The homeostasis model assessment of insulin resistance indicated that, in comparison with the control mice, the mice exposed to intermittent hypoxia showed 15% lower insulin resistance (p = 0.09) and 21% higher pancreatic β-cell function (p = 0.01). Immunohistochemical staining of the islets showed no significant differences between the two groups in terms of the area or intensity of α- and β-cell staining for insulin and glucagon. Conclusions: To our knowledge, this is the first report of the effect of intermittent hypoxia on UCP2 expression. Our findings suggest that UCP2 regulates insulin production in OSA. Further study of the role that UCP2 plays in the glycemic control of OSA patients is warranted.

Keywords: Blood glucose; Sleep apnea syndromes; Pancreas; Glucagon-secreting cells.

Objective: To determine the prevalence of emotional and behavioral disorders in adolescents with asthma and to compare it with that of adolescents without asthma. Methods: A transversal study using the Strengths and Difficulties Questionnaire, administered to adolescents with or without asthma, ranging from 14 to 16 years of age and randomly selected from schools in the city of Belo Horizonte, Brazil. Results: The prevalence of emotional and behavioral disorders in adolescents with and without asthma was 20.4% (95% CI: 14.5-27.8%) and 9.0% (95% CI: 6.1-12.8%), respectively. Among adolescents with asthma, 56.6% (95% CI: 48.3-64.5%) presented normal scores, and 23.0% (95% CI 16.8-30.7%) presented borderline scores. Among adolescents without asthma, 75.0% (95% CI: 69.7-79.6%) presented normal scores, and 16.0% (95% CI: 12.2-20.7%) presented borderline scores. The median total score on the questionnaire was 14 and 12 among subjects with and without asthma, respectively (p < 0.01). In the final logistic regression model, adjusted for socioeconomic variables, the association between emotional/behavioral disorders and the following variables remained significant: being female (OR = 1.98; 95% CI: 1.10-3.56; p = 0.02) and having asthma (OR = 2.66; 95% CI: 1.52-4.64; p = 0.001). Conclusions: The prevalence of emotional and behavioral disorders is higher in adolescents with asthma than in those without asthma, underscoring the need for a holistic, interdisciplinary approach.

Keywords: Asthma; Epidemiology; Prevalence; Adolescent; Psychology; Behavioral symptoms.

Objective: Studies characterizing asthma phenotypes have predominantly included adults or have involved children and adolescents in developed countries. Therefore, their applicability in other populations, such as those of developing countries, remains indeterminate. Our objective was to determine how low-income children and adolescents with asthma in Brazil are distributed across a cluster analysis. Methods: We included 306 children and adolescents (6-18 years of age) with a clinical diagnosis of asthma and under medical treatment for at least one year of follow-up. At enrollment, all the patients were clinically stable. For the cluster analysis, we selected 20 variables commonly measured in clinical practice and considered important in defining asthma phenotypes. Variables with high multicollinearity were excluded. A cluster analysis was applied using a two-step agglomerative test and log-likelihood distance measure. Results: Three clusters were defined for our population. Cluster 1 (n = 94) included subjects with normal pulmonary function, mild eosinophil inflammation, few exacerbations, later age at asthma onset, and mild atopy. Cluster 2 (n = 87) included those with normal pulmonary function, a moderate number of exacerbations, early age at asthma onset, more severe eosinophil inflammation, and moderate atopy. Cluster 3 (n = 108) included those with poor pulmonary function, frequent exacerbations, severe eosinophil inflammation, and severe atopy. Conclusions: Asthma was characterized by the presence of atopy, number of exacerbations, and lung function in low-income children and adolescents in Brazil. The many similarities with previous cluster analyses of phenotypes indicate that this approach shows good generalizability.

Keywords: Asthma/classification; Asthma/etiology; Child; Adolescent.