Voluntary cough suppression as an indication of symptom severity in upper respiratory tract infections.

The aim of the present study was to determine whether the ability to suppress cough voluntarily is an index of cough severity in upper respiratory tract infection. Cough was measured by means of a microphone linked to a pen recorder and subjects were instructed to voluntarily suppress cough in order to determine cough suppression time. Subjective scores of symptom severity, mood and psychological parameters were made prior to cough measurements. The baseline frequency of cough showed a distribution towards the higher frequencies, with a median of 2.1 (lower quartile 1.2, upper quartile 3.2) coughs.min-1. The results for cough suppression fell into two distinct groups, one group reaching a breaking point within 12.6 min; and another group which did not cough during the 20 min cough suppression period. In the group of subjects which broke from the cough suppression, there was an inverse relationship between the cough suppression time and the baseline frequency of cough. The median frequency of cough following cough suppression was significantly greater than the baseline median frequency of cough. The subjects who reached a breaking point had a greater baseline frequency of cough and a greater symptom severity score, and they also felt more feeble, clumsy, sad and antagonistic than the group which did not reach a breaking point. The subjects who reached a breaking point had significantly greater scores for the psychology parameter of obsessional symptoms than the group which did not reach a breaking point.(ABSTRACT TRUNCATED AT 250 WORDS)