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In order to discover whether progression of chronic bronchitis may be delayed by control of recurrent infection it was'decided in 1957 to carry out a controlled double-blind trial of chemo- prophylaxis and chemotherapy on cases of chronic bronchitis with a history of recurrent infection but with mild disability, and to observe the associated changes of respiratory function.To obtain the necessary numbers of subjects chest physicians in various parts of the country were invited to participate, and they agreed upon a plan (approved by the then Antibiotics Clinical Trials Committee of the Medical Research Council).This report is concerned with the frequency and severity of ill- nesses and changes in ventilatory capacity during the first five years of the trial. Methods Recruitment of CasesThe trial was carried out on men aged 40-59 in full employment who had a productive cough (grade 2, Medical Research Council, 1960) and who had had at least two chest illnesses with increased phlegm, and a total absence from work of at least three weeks during the previous three years.The forced expiratory volume in one second (F.E.V) had to be over 1.4 litres.Men were excluded if they suffered from any other disabling condition.Considerable difficulty was encountered in recruitment.Most men attending chest clinics for chronic bronchitis have F.E.V. levels below 1.4 litres.Most men with high values of F.E.V. had infrequent illnesses, while those with recurrent ill- nesses usually had low values, and this was the most common reason for rejection of otherwise suitable patients.It was hoped that each of the 13 participating physicians would obtain 60 cases within the first year, but only one clinic reached this number despite recruitment over two years (see Table I).There is evidence that different clinics recruited rather different types of subject. Therapeutic RegimenOxytetracycline was chosen for prophylaxis, initially in a dose of 0.5 g. once daily in the morning from mid-September to mid-April each year.It was hoped that if this small and economic dose proved effective it might be more practicable on a national scale than a larger, more expensive dose.Boxes of
A Sat, study studied this question.