Evaluation of symptoms & spirometry in children treated for asthma

Asthma is a chronic inflammatory disease of airways characterized by bronchial hyper-responsiveness and reversible airway obstruction1. Pulmonary function tests, mainly spirometry are gold standard tools for objective evaluation in childhood asthma2. Spirometry determines the degree of airway obstruction and its response to treatment.3 However, most asthmatic children, independent of the disease severity, have been found to have normal forced expiratory volume (FEV) values especially when asymptomatic45. Hence, the role of pulmonary function tests in short and long term evaluations of childhood asthma remains controversial. Also, reliable spirometric measurements depend on the patient's ability to perform a forceful expiratory maneuver which is difficult in young children. Hence, the clinical picture in terms of signs and symptoms is also of paramount significance6. The lung function measurements give information about the patients’ physiology in an objective way, whereas symptoms give more information about how the disease is affecting the patient6. Though it is known that with treatment there is improvement in both symptoms and lung function measures, the levels of improvement in each of the parameters are not yet clear. This emphasizes the need for further studies to determine how spirometric measures and the clinical features improve with treatment. Hence we undertook this study to determine the clinical improvement and the changes in the spirometric measurements with treatment in newly diagnosed cases of asthma in children and to compare the change in the symptom score and spirometric measurements.

Material & Methods

The present study was a prospective observational study initiated after the approval of the protocol and the study design by the Institutional Ethics Committee, and conducted at the Paediatric Chest Clinic at KEM Hospital, a tertiary care referral hospital in Mumbai, Maharashtra, India. The study included children between 6 and 12 yr of age who consecutively presented at this clinic over a period of one year (January to December 2010) with signs and symptoms suggestive of asthma (newly diagnosed) and who were able to perform spirometry. Patients who were treated elsewhere, on long term oral steroids, those who could not perform spirometry or refused to give consent were excluded. A total of 37 patients were identified and five were lost to follow up. Only 32 patients were followed up for a period of six months. Written informed consent of the parent/guardian and assent of children above seven years of age were obtained. The children were assessed and classified according to severity of the symptoms as per the Global Initiative for Asthma (GINA) guidelines 20097. The baseline symptom score and spirometric measurements were done. Spirometric readings were obtained on a portable standardized spirometer (spirolab III, MIR, Italy). The symptom score was determined by using the Childhood Asthma Control Test: C-ACT8. This test consists of seven questions related to the last four weeks, of which four are to be answered by the child and three by the parents. The total score can range from 0-27. The C-ACT is a validated test to assess asthma control and identify children with inadequately controlled asthma8. The children were started on treatment according to GINA guidelines7. Metered dose inhaler or rotahaler was used to deliver beta 2 agonists and steroids. The drugs were stepped up/down as required according to the guidelines. The parents were educated about the disease and treatment, the symptoms and signs of acute exacerbation and the importance of avoiding triggering factors. They were trained to use the inhalation devices and the technique was checked at every visit to ensure adequate drug delivery. Regular visits were ensured by giving the date for the next visit and patients who did not turn up on the day of the scheduled visit were reminded telephonically. Thus follow up and treatment compliance was ensured. The children were followed up at six weeks, three and six months of treatment and assessed clinically in terms of symptom score. Spirometric measurements were performed at every visit. The tests were not applied during an acute exacerbation. Spirometry was performed when the patient was not on bronchodilators.

The following lung function parameters were monitored during the study period: FEV₁ (forced expiratory volume in 1 second), FVC (forced vital capacity), FEV₁/FVC ratio, and PEFR (peak expiratory flow rate).

Statistical analysis: The data were tested for normality using D’Agostino-Pearson omnibus normality test9 and were found to be not normally distributed. The data were analyzed using the ‘Wilcoxon signed Rank sum test for the symptom score and paired t test for the lung function parameters. The symptom score and each of the lung function parameters were compared and Pearsons correlation factor was calculated.

Results & Discussion

The mean age of the patients was 8.72 ± 1.95 yr; 20 (62.5%) were males and 12 (37.5%) were females. The male: female ratio was 1.67:1. The height was 125.50 ± 12.23 cm, and the weight was 22.19 ± 6.7 kg. Twenty seven patients belonged to mild persistent type and five were of moderate persistent type of asthma. The mean symptom score, FEV₁, FVC, FEV₁/FVC and PEFR values at each visit and the improvement in the various parameters when compared to baseline are shown in Table I. Significant improvement in the symptom score was evident at six weeks of therapy while the lung function parameters, FEV₁ and FVC showed significant improvement at three months. PEFR was found to show improvement at six months. FEV1/FVC did not show significant improvement during the study period. Table II shows improvement in the various parameters during follow up when compared to the previous visit. Improvement was noticed in all the spirometric parameters at six months follow up. There was a positive linear correlation between the changes in symptom score and FEV₁, FVC and PEFR (r=0.91, P<0.001; r=0.93, P<0.001; and r=0.88, P<0.001, respectively).

Table I Mean symptom score, and lung function parameters at baseline and upto six months of follow up

Table II Improvement in symptom score and lung function parameters at follow up when compared to previous visit

Asthma control and severity have been conventionally assessed using several indices which have included symptoms, level of treatment and lung function56. It is apparent that no single measure of disease control can encompass all the clinical problems in asthma6. It is also known that patients with similar levels of lung function may experience a wide range of severity and morbidity5. Thus, there is always a risk of underdiagnosis or overdiagnosis of asthma if only the spirometric measurements (FEV₁) were taken into account since majority of children irrespective of the severity of asthma tend to have a normal FEV₁ when asymptomatic45. Stout et al10 reported that one third of the children with asthma were reclassified into a more severe asthma category when pulmonary functions were taken into consideration in addition to symptom frequency. Measurements of pulmonary functions require a high degree of patient's cooperation and the readings reflect a onetime measurement of the child's status and so are probably of questionable value2311. Serial follow ups and monitoring of the lung function measures are more reliable than a single reading which usually does not convey much meaning6. This highlights the need to use multiple parameters in assessing children with asthma6. Our study showed that with appropriate treatment and regular follow up, there was a significant improvement in both the symptom score and the lung function measures. The improvement was initially apparent in the symptom score of the patient.

In a study on asthmatic children, where the improvement in symptom score at 2, 4 and 8 wk of starting treatment was determined, the mean symptom score showed a significant change from 57.80 to 49.5 at two weeks, 37.74 and 27.80 at four and eight weeks, respectively (P<0.01)12. There was a significant improvement in FEV₁, FVC and PEFR at the same time, showing that improvement in both symptom score and lung function measures12. Another study showed that at the end of three months treatment, there was a significant improvement in the symptom score (8.35±0.67 vs 1.76±0.27, P<0.001)13. Improvement was also noticed in the lung function parameters- FEV₁ (68.25±2.83 to 76.28±2.47, P<0.002) and PEFR (63.95±3.13 to 75.68±3.66, P<0.001)13. Zhang et al11 showed that perception of symptomatic improvement by both parents and children correlated weakly with the changes in pulmonary function parameters during the study period. This was attributed to the fact that the lung function measures represented the pulmonary functional status at the moment of visit while the symptom score reflected the improvement over a period of time11. Planned education interventions reduce the symptom frequency and duration and the need for oral steroid burst therapy14. Also, with proper education and follow up, children were found to take their medications more regularly14.

The improvement was initially evident in the symptom score as early as the six weeks of treatment while the improvement in the lung functions was noticed at three months. It indicates that the subjective improvement precedes improvement in objective parameters. So the symptom score, the FEV₁, FVC and PEFR are all good indicators of response to treatment in asthma. In addition to drug therapy, the role of psychosocial and other environmental factors like avoidance of triggers in the control of asthma cannot be underestimated. The small sample size and the shorter duration of follow up were the main limitations of this study. A long term follow up of the patients would yield valuable information regarding the trends in both symptom score and lung function measures.