Assessment of improvement in health gain and costs of care with the application of the breath test in wheezing preschool children
asthma-like symptoms
The effect of the intervention will be assessed by comparing the outcome measures between the intervention and the usual care group in the RCT. Dichotomous parameters will be tested with the chi-square test. Continuous variables will be tested for significance with the unpaired t-test for normally distributed parameters and the Mann Whitney-U test in case of a not-normal distribution.Total treatment costs will be calculated by multiplying resource use with the costs per unit. Resource use (visits to the general practitioner or specialist, emergency visits, hospital admission, lung function tests and other diagnostic procedures, the breath test, (over-the-counter) medication, and lost work days by parents due to sickness of the child) will be obtained from a specially designed questionnaire with a recall period of three months. The parents will fill out this questionnaire at baseline and at 3 months interval during the follow-up. Sources for valuation of the costs will be cost-prices of the Dutch manual for costing and cost-prices from the Dutch pharmacotherapeutic compass [The cost-effectiveness analysis from the healthcare perspective will be based on symptom control according to the TRACK questionnaire at 1 year follow-up (primary outcome measure). The cost-effectiveness analysis from the societal perspective will be based on the EQ-5D-Y. The EQ-5D-Y will be completed at baseline and at 3 months intervals during the follow-up, and will be filled out by one of the parents.A cost-effectiveness analysis will be performed from a societal and healthcare perspective with a time horizon of 2 years. Incremental cost-effectiveness ratios will be calculated as societal cost per QALY (societal perspective) and health care cost per additional child with control of asthma-like symptoms (healthcare perspective). Standard sensitivity- and bootstrap analysis will be performed to address uncertainty regarding costs and cost-effectiveness outcomes. Cost-effectiveness acceptability curves will be constructed reflecting the probability that the diagnostic breath test is cost-effective for a range of threshold values. Costs and effects after one year will be discounted at 4.0% and 1.5% respectively, according to the Dutch guidelines for health economic evaluation [All outcome parameters and corresponding outcome measures and methods of analysis are listed in Table 