Chest
Volume 120, Issue 4, October 2001, Pages 1121-1128
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Clinical Investigations
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Application and Validation of a Computerized Cough Acquisition System for Objective Monitoring of Acute Cough: A Meta-analysis

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Study objective

The purpose of the meta-analysis was to understand the antitussive effect of treatment with dextromethorphan hydrobromide, 30 mg, vs placebo over a 3-h treatment period in patients with cough due to uncomplicated upper respiratory tract infection (URTI), and to show that the computerized system for acquisition and analysis of cough sound was consistent and reproducible across the individual studies.

Study design

The six studies used for the meta-analysis were randomized, double-blind, parallel-group, single-dose, placebo-controlled studies with a 3-h postdose cough evaluation period.

Setting

One study was conducted in Durban, South Africa, and five studies were conducted in Bombay, India. Four studies took place in clinics, and two studies were in-home studies.

Patients

Seven hundred ten adult patients with cough due to uncomplicated URTI who were otherwise healthy and who satisfied the inclusion/exclusion criteria for the meta-analysis.

Measurements and results

For each patient, a standard baseline was calculated pretreatment, then a 3-h continuous cough recording was made after treatment was initiated. Five efficacy variables were measured in 30-min intervals: cough bouts, cough components, cough effort, cough intensity, and cough latency. The meta-analysis showed consistent results across most of the studies for each of the efficacy variables. It demonstrated significantly greater overall reductions in cough bouts, cough components, and cough effort, and an increase in cough latency for patients treated with dextromethorphan hydrobromide, 30 mg, vs those treated with placebo.

Conclusion

The results of a meta-analysis of the six clinical studies show that the antitussive effect of a single dose of dextromethorphan hydrobromide, 30 mg, has been established. The consistent nature of the results shows that the computerized cough acquisition and analysis system is a valid and reproducible methodology for evaluating cough associated with URTI.

Section snippets

Computerized System

Our original computerized cough acquisition and analysis system has been described previously.8 The system was further made portable to record cough signals from human volunteers who stay at home during clinical studies. This new computerized audio timed (CAT) recorder is portable, uses a telemetric method, and operates for a long duration to enable in-home monitoring of cough for > 24 h.

The main components of the recorder are shown in Figure 1. A contact microphone (or accelerometer), attached

Results

The meta-analysis was based on a total of 710 subjects, comprising all evaluable subjects who received 30 mg dextromethorphan (n = 356) vs all evaluable subjects who received placebo (n = 354).

Discussion

This meta-analysis of six studies provides new objective evidence for the known antitussive effect of dextromethorphan using a computerized system to acquire and analyze cough sounds. The consistent nature of the results shows that the computerized cough acquisition and analysis system is reproducible and is a valid methodology to evaluate cough objectively.

The methodology was consistent across different environments; the results of the in-clinic studies were similar to those carried out in

Conclusion

We have developed a reliable, noninvasive computerized methodology that is calibrated and validated for objectively assessing the efficacy of antitussives by measuring a comprehensive range of parameters. We have presented the results of a meta-analysis of six clinical trials using this methodology and have shown that the antitussive effect of a single, oral 30-mg dose of dextromethorphan has been reproducibly established in these studies in acute cough due to uncomplicated URTI. We have also

Acknowledgment

We thank Professor John Widdicombe for his assistance and advice. We also thank Kerry Dillingham for her hard work and statistical expertise in executing the meta-analysis and Tex Warnes for his help in producing Figures 3 and 4.

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Clinical studies carried out and financed by Procter and Gamble, Corporate Health Care Research Center, Mumbai, India.

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