Asthma management, education and environmental interventions have been reported as cost‐effective in a previous review (Pharm Pract (Granada), 2014;12:493), but methods used to estimate costs and outcomes were not discussed in detail. This review updates the previous review by providing economic evidence on the cost‐effectiveness of studies identified after 2012, and a detailed assessment of the methods used in all identified studies. Twelve databases were searched from 1990 to January 2016, and studies included economic evaluations, asthma subjects and nonpharmacological interventions written in English. Sixty‐four studies were included. Of these, 15 were found in addition to the earlier review; 53% were rated fair in quality and 47% high. Education and self‐management interventions were the most cost‐effective, in line with the earlier review. Self‐reporting was the most common method used to gather resource‐use data, accompanied by bottom‐up approaches to estimate costs. Main outcome measures were asthma‐related hospitalizations (69%), quality of life (41%) and utility (38%), with AQLQ and the EQ‐5D being the most common questionnaires measured prospectively at fixed time points. More rigorous costing methods are needed with a more common quality of life tool to aid greater replicability and comparability amongst asthma studies.

IntroductionThe potential of exhaled breath condensate (EBC) as a non-invasive indicator of airways disease has been studied for three decades or more. 8-isoprostane is a product of lipid peroxidation which can be detected within EBC. Studies have reported this as a potential objective indicator of oxidative stress in asthma. We therefore aimed to assess the evidence for the use of 8-isoprostane in exhaled breath condensate (EBC) as a biomarker in adult asthma.DesignA systematic review and meta-analysis of EBC 8-isoprostane in asthma.MethodsWe searched a number of online databases (including PubMed, Embase and Scopus) in January 2016. We included studies of adult non-smokers with EBC collection and asthma diagnosis conducted according to recognised guidelines. We aimed to pool data using random effects meta-analysis and assess heterogeneity using I2. Study quality and risk of bias was assessed using QUADAS-2 and GRADE.ResultsWe included twenty studies, the findings from which were inconsistent. Seven studies (n = 329) reported 8-isoprostane concentrations in asthma to be significantly higher than that of control groups, whilst six studies (n = 403) did not. Only four studies had results appropriate for inclusion in a random effects meta-analysis of mean difference between asthma and controls (see Figure 1). This found a statistically significant between-groups difference of +22 pg/ml in asthma.Confidence in the result is limited by the small number of studies; by substantial methodological and statistical heterogeneity (I2 = 94); and by an inability to assess the risk of bias in key domains of the quality assessment tool.ConclusionThe clinical value of EBC 8-isoprostane as a quantitative assessment of oxidative stress in asthma remains unclear due to variability in results and methodological heterogeneity. It will be essential to develop accurate, reliable and standardised methods of both EBC collection and 8-isoprostane analysis if its use as a biomarker in asthma is to be evaluated.Abstract S1 Figure 1Random effects meta-analysis of mean between-group difference (asthma vs controls)