Inflammatory Indices in Predicting the Failure of Inhaled Corticosteroids Reduction in Young Participants With Asthma

Introduction Guidelines for the treatment of asthma recommend the use of the smallest dose of inhaled steroid (ICS), which allows to maintain control of the symptoms of the disease. The GINA 2006 guidelines proposed (and later editions it upheld) that in the case of symptom control by monotherapy with ICS, to reduce their dose every 3 months, up to the lowest dose administered once a day, which should be used for one year before taking possible decision to stop it.

There are no clear of simple and sensitive indicators that would allow detection of a threatening loss of control before the clinical symptoms worsen.

Aim of the study Evaluation of the usefulness of induced sputum eosinophilia and other inflammatory indices [exhaled nitric oxide (NO), exhaled breath temperature (EBT), bronchial hyperresponsiveness] in predicting the failure of treatment reduction with inhaled corticosteroids in stable asthma in children and adolescents.

Subjects Participants aged 12-18 years with stable asthma (mild or moderate), treated in the Allergy Clinic of the Hospital in Lesko with medium doses in ICS. The severity of asthma was initially determined in accordance with the GINA criteria and verified during several years of observation by the assessment of clinical symptoms, functional examinations and the dose of inhaled steroids controlling the disease.

Project description A prospective, observational, single-blind study (blinded for a clinician in the field of inflammatory parameters). Clinician takes decision about possible reduction of ICS dose basing on clinical data only - is not aware of the results of the inflammatory parameters measurement.

The study is consisting of two periods:

First period (run - in):

A four-week run - in period in which clinical symptoms and the use of short acting beta2 agonists (SABA) and PEFR are monitored. At the end of this period, in participants with stable disease the following parameters are measured: eNO, EBT, spirometry, and sputum induction with hyperosmolar saline in combination with the hyperresponsiveness. Before the reduction of treatment on another day, an exercise challenge test is also performed.

The criteria for the stability of asthma in the run - in period are:

• symptoms no more than 3 times a week
• SABA use less than 3 times a week
• without night wake up
• PEFR variability below 20%
• FEV1 above 80% of predicted

Second period of the study - reduction of anti-inflammatory therapy. In participants with previously stable course of the asthma (confirmed in the run -in period), the control of asthma is monitored regularly throughout the observation period. All participants run an observation card (clinical symptoms) and PEFR measurements. Monthly spirometry, exhaled NO and exhaled breath temperature measurements are performed. Every 3 months and one month after the change of treatment (i.e in months 0, 1, 3, 4, 6 and 7), the hyperresponsiveness measurement is carried out with the sputum induction (combined method, [7]). Two months after the dose change (months 2, 5, 8) the exercise challenge test is carried out.

Every 3 months control of the asthma symptoms is evaluated taking account the clinical data, and possible change of ICS dose is considered. Results of bronchial reactivity measurements and sputum cytology are not known to clinician who decide on a possible ICS dose change - he is blinded to the results of tests and the therapeutic decision is based solely on clinical evaluation.

In participants with a stable course of the disease over past 3 months, the dose of ICS is halved, in accordance with GINA guidelines. In the case of loss of asthma control, appropriate treatment modifications are administered and the patient is withdrawn from the study.

Participation in the study is continued until asthma control is lost or the lowest daily dose is reached (200 mcg, calculated as budesonide equivalent) - without losing asthma control at next visit.

Measurements

1. Daily clinical evaluation by the patient:

• symptoms score according to the Santanello questionnaire
• PEFR measurement

1. Every month

• Asthma Control Test
• spirometry [forced expiratory flow in 1st second (FEV1), forced vital capacity (FVC), forced expiratory flow between 25% and 75% of FVC (FEF25-75)]
• eNO measurement
• exhaled breath temperature measurement (EBT)

1. every 3 months

• quality of life test (QoL, Polish version of the questionnaire), i.e. months 3, 6, 9
• cytological evaluation of induced sputum (i.e. months 0, 1, 3, 4, 6, 7)
• assessment of bronchial hyperresponsiveness:
• one month after the ICS dose reduction and then before each subsequent dose reduction in ICS ((i.e. months 0, 1, 3, 4, 6, 7) - during the sputum induction with hyperosmolar salt (combined method)
• 2 months after each treatment reduction (i.e. months 2, 5, 8): exercise challenge test (6-minute free-running test monitored by pulse)

Criteria for loss of control [1, 6] - any of the following:

• use of bronchodilators> 5 times a week
• the need for treatment with oral corticosteroids
• PEFR decrease above 20% for 2 consecutive days, compared to the average run-in period In the case of loss of asthma control, beta-mimetic will be administered (temporarily) and return to the chronic administration of the previous, twice higher dose of ICS is restored (or further increase of treatment). In severe exacerbations, inclusion of oral steroids will be considered.

Criteria for discontinuation of participation in the study

1. Loss of asthma control (treatment strategy: beta-mimetic temporarily, return to dose of ICS before reduction or further increase of treatment; in severe exacerbations, inclusion of oral steroids).
2. Lack of adherence to the recommendations or failure to report.

The staff of the center has experience in the production of sputum induction in participants with asthma [Ciółkowski J, Mazurek H, Stasiowska B. Evaluation of step - down therapy from an inhaled steroid to montelukast in childhood asthma. Allergologia et immunopathologia (Madr.), 2014: Jul - Aug; 42 (4): 282 - 288].

The test will be performed in conditions ensuring patient safety, with the availability of an anaesthesiologist and anti-shock kit.