ASTHMA CONTROL COST-UTILITY RANDOMIZED TRIAL EVALUATION.

Rationale:
The central question is whether an attempt to achieve complete control of all features of asthma, with accompanying high dosis of medication should be made, and whether patients and society value the potential incremental benefit sufficiently to concur with such a treatment approach. Therefore the aim of the study is to assess patient preferences and cost-effectiveness of two treatment strategies aimed at achieving different levels of clinical control:

1. Partly controlled asthma;

2. Controlled asthma.

A third strategy adds a nitric oxide measurement:

3. Controlled asthma based on exhaled nitric oxide as an additional disease marker.

In the third treatment strategy an algorithm was designed that combines the results of an NO-measurement and the composite score measurements. The question is whether this leads to better asthma control in a general practice population and whether it is a cost-effective addition.

Methods:
720 Patients with mild to moderate persistent asthma from general practices with a nurse practitioner or physician assistant, age 18-50 yr, need for daily treatment with inhaled corticosteroids (more then 3 months usage of inhaled corticosteroids in the previous year), will be identified via primary care patient registries, including Leiden, Nijmegen and Amsterdam areas. The design is a cluster-randomised trial with 40 general practices in all three arms and 12 months follow-up. The patients will visit the general practice at baseline, 3, 6, 9 and 12 months. At each planned and unplanned visit to the general practice treatment will be adjusted with support of an ICT-based asthma monitoring system supervised by a central coordinating specialist nurse. Patient preferences and utilities will be assessed by questionnaire and interview. Data on asthma control, treatment step, adherence to treatment, utilities and costs will be obtained every 3 months. Differences in societal costs (medication, other (health) care and productivity) will be compared to differences in the number of limited activity days and in quality adjusted life years (Dutch EQ5D, SF6D, e-TTO, VAS).

1. A treatment strategy aimed at well controlled asthma is more (cost-)effective as compared to a treatment strategy aimed at achieving partly controlled asthma;

2. A treatment strategy aimed at well controlled asthma is (cost-)effective when the treatment step is additionally guided by measurements of exhaled nitric oxide (NO) as compared to a treatment strategy aimed at achieving well controlled asthma or partly controlled asthma.

Baseline, 3months, 6 months, 9months, 12 months + unplanned visits.

1. PC-strategy: aiming to achieve partly controlled asthma based on asthma control measures;

2. C-strategy: aiming to achieve controlled asthma based on asthma control measures;

3. FeNO-strategy: aiming to achieve controlled asthma based on asthma control measures and an indirect marker of airways inflammation.