Systematic review of clinical effectiveness of pressurised metered dose inhalers versus other hand held inhaler devices for delivering corticosteroids in asthma. (Papers).

Abstract

Objective To determine the clinical effectiveness of pressurised metered dose inhalers (with or without spacer) compared with other hand held inhaler devices for the delivery of corticosteroids in stable asthma.

Design Systematic review of randomised controlled trials.

Data sources Cochrane Airways Group trials database (Medline, Embase, Cochrane controlled clinical trials register, and hand searching of 18 relevant journals), pharmaceutical companies, and bibliographies of included trials.

Trials All trials in children or adults with stable asthma that compared a pressurised metered dose inhaler with any other hand held inhaler device delivering the same inhaled corticosteroid.

Results 24 randomised controlled trials were included. Significant differences were found for forced expiratory volume in one second, morning peak expiratory flow rate, and use of drugs for additional relief with dry powder inhalers. However, either these were within clinically equivalent limits or the differences were not apparent once baseline characteristics had been taken into account. No significant differences were found between pressurised metered dose inhalers and any other hand held inhaler device for the following outcomes: lung function, symptoms, bronchial hyper-reactivity, systemic bioavailability, and use of additional relief bronchodilators.

Conclusions No evidence was found that alternative inhaler devices (dry powder inhalers, breath actuated pressurised metered dose inhalers, or hydrofluoroalkane pressurised metered dose inhalers) are more effective than the pressurised metered dose inhalers for delivery of inhaled corticosteroids. Pressurised metered dose inhalers remain the most cost effective first line delivery devices.

Introduction

Numerous inhaler devices and drug combinations are now available for delivering inhaled corticosteroids in patients with asthma. These include breath actuated pressurised metered dose inhalers, dry powder devices, and chlorofluorocarbon-free or hydrofluoroalkane pressurised metered dose inhalers. The cost of the drug used in specific devices varies widely, but there are no explicitly evidence based guidelines on which are the most effective. We conducted a systematic review to determine the clinical effectiveness of the standard chlorofluorocarbon containing pressurised metered dose inhaler versus other hand held inhaler devices in delivering corticosteroids to patients with stable asthma.

Methods

Identification and selection of trials

We identified trials published from 1966 to July 1999 by computerised searches of the Cochrane Airways Group trials database, which includes Medline, Embase, CINAHL, hand searching of 18 relevant journals and proceedings of three respiratory societies, and review of the bibliographies of included trials (see www. ncchta.org/execsumm/summ526.htm). We included citations in any language. We also contacted the pharmaceutical companies that manufacture inhaled asthma drugs and searched the reference lists of included trials for further studies.

We considered only randomised controlled trials in children or adults that were laboratory, hospital, or community based and lasted for four weeks or longer. Trials were included if they compared clinical outcomes of a single drug delivered by standard pressurised metered dose inhaler (with or without a spacer device) versus any other hand held inhaler device. Trials comparing different doses of the same drug were included.

We included the following outcomes: lung function, quality of life measures, symptom scores, drugs for additional relief, acute exacerbation, days off work or school, treatment failure, patient compliance, patient preference, adverse effects, bronchial hyper-reactivity, and systemic bioavailability.

Analysis of data

We analysed data using Review Manager (RevMan, Version 4.1) statistical software. (1) For the meta-analysis, we used weighted mean differences for outcomes using the same measures on continuous scales (for example, forced expiratory flow in one second) or standardised mean differences for outcomes that used different scales (for example, forced expiratory flow in one second absolute and improvement from baseline).

The pressurised metered dose inhaler was compared with each other hand held inhaler device separately. Each of these device comparisons was further separated into the different trial designs--that is, crossover and parallel. Trials were analysed separately for …