Feasibility of a chemoprophylaxis trial in India against tuberculosis. A pilot study.

A pilot study in Bangalore to investigate the feasibility of a chemoprophylaxis trial with isoniazid is described.For a chemoprophylaxis trial, 2 basic requirements are that a large number of participants must take the drug and that reliable estimates of the amount of drug consumed should be available. Distribution of weekly supplies of pills for self-medication was tried and actual consumption was checked by urine examination using the Belles-Littleman filter-paper spot test. Except during the first month, the proportion of positive urine samples was very small.Estimating drug consumption by "pill counting" or by means of house-to-house interview was not reliable. These methods are not recommended for a chemoprophylaxis trial in India.Direct administration of pills to each participant every day for 6 months by a locally employed person resulted in a much higher consumption of pills. In spite of some deliberate false recording and some genuine recording errors, the results are considered encouraging enough to warrant further trials. Procedures are simpler and records of consumption for each individual are available. The method also provides the opportunity to use the individual, and not the family, as the unit for randomization between treatments.The proportion of positive urine samples provides an objective means of assessing the reliability of estimates of drug intake by other methods but large numbers of urine samples would be required if this method were to be used independently for estimating individual pill consumption.