Efficacy and safety of phosphodiesterase 4 inhibitors in patients with asthma: A systematic review and meta-analysis.

Phosphodiesterase 4 (PDE4) inhibitors are a novel medication approved for airway inflammatory diseases including chronic obstructive pulmonary disease. Their role and application in asthma are controversial and not defined. A comprehensive search was performed in major databases (1946-2016) using the keywords: 'phosphodiesterase 4 inhibitor' or 'roflumilast' and 'asthma'. Placebo-controlled trials reporting lung function, airway hyperresponsiveness by direct challenge, asthma control and exacerbations, and adverse events were included. Random or fixed-effects models were used to calculate odds ratios (OR) and mean differences between the two treatment groups. Statistical analyses were conducted using Mann-Whitney U-tests and Cochrane systematic review software, Review Manager. Seventeen studies were included in the systematic review, of which 14 studies were included in the meta-analysis. Except for significant statistical heterogeneity in pre- and post-challenge predicted percentage of forced expiratory volume in 1 s (FEV1 %; I2 = 72%, χ2 = 3.35, P = 0.06), there was no heterogeneity in outcome measures. Roflumilast (500 µg) significantly improved FEV1 (mean difference: 0.05, 95% CI: 0.01-0.09, Z = 2.50, P = 0.01), peak expiratory flow, asthma control and exacerbations, but showed variable effects on airway responsiveness to methacholine and a 20% fall in FEV1 .Of note, PDE4 inhibitors were accompanied with significantly higher adverse events such as headache (OR: 3.99, 95% CI: 1.65-9.66, Z = 3.07, P = 0.002) and nausea (OR: 5.53, 95% CI: 1.38-22.17, Z = 2.41, P = 0.02). In patients with mild asthma, oral PDE4 inhibitors can be considered as an alternative treatment to regular bronchodilators and inhaled controllers.