The main aim of the meta-analysis was to recognize the antitussive effect of treatment with dextromethorphan hydrobromide, 30 mg, versus placebo over a 3-hour treatment period in patients who are having cough because of simple upper respiratory tract infection (URTI). Also, to validate that the computerized system for analysis of cough sound was steady and reproducible throughout the individual studies.

Six double-blind, randomized, single-dose, parallel-group, placebo-controlled studies with a 3-hours post-dose cough evaluation period were carried out. One of the studies was conducted in Durban, South Africa, and the rest five studies were conducted in Bombay, India. Four studies were done in clinics and the other two studies were in-home.

Seven hundred and ten adult patients with cough because of simple URTI, were healthy and had satisfied the inclusion/exclusion criteria for this meta-analysis.

A standard baseline was designed for pre-treatment, then a 3-hour continuous cough recording was done after treatment for each patient. Five efficacy variables were calculated in 30-minutes intervals: cough bouts, cough effort, cough components, cough intensity and cough latency. The meta-analysis exhibited consistent and reliable results through most of the studies for the efficacy variables. It also demonstrated greater overall significant reductions in cough bouts, cough components, and cough effort along with an increase in cough latency for patients who were treated with dextromethorphan hydrobromide, 30 mg, with comparison to those treated with placebo.

The results of a meta-analysis of these six clinical studies demonstrated that the antitussive effect of a one single dose of dextromethorphan hydrobromide, 30 mg, was established. Also, the consistent nature of the results of the meta-analysis displayed that the computerized cough acquisition and analysis system is a reproducible and valid methodology for assessing cough that is associated with URTI.

Source: Pavesi L, Subburaj S, Porter-Shaw K. Application and validation of a computerized cough acquisition system for objective monitoring of acute cough: a meta-analysis. Chest. 2001 Oct;120(4):1121-8.