Sputum-submission guidance produces 63% more positive tests for tuberculosis in women, and could be a highly cost-effective intervention to improve case detection in low-income countries. The findings are reported in an Article published in this week’s edition of The Lancet.
Mishal Khan, Clinical Research Unit, London School of Hygiene and Tropical Medicine, University of London, UK and colleagues did their study to find out why in various low income countries, women with suspected tuberculosis are less likely to test smear positive than men after providing sputum samples.
The authors say: “Previous studies have suggested that cultural inhibitions about producing deep sputum, particularly in public places, and lack of knowledge about tuberculosis diagnosis in low-income countries might affect the quality of specimens submitted by women.”
The researchers studied 1,494 women and 1,561 with suspected tuberculosis attending the Federal Tuberculosis Centre in Pakistan. The patients were randomly assigned to either receive sputum-submission guidance before producing their sample, or to receive no guidance.
They found a 63% higher case detection rate in women who received guidance compared to those who did not. Sputum submission guidance also increased the proportion of men testing positive, but the impact was not as large as in women.
The authors say: “The effect [of guidance] was most probably greater in female patients because women were less knowledgeable about the difference between sputum and saliva and the need to submit a proper sputum sample for diagnosis of tuberculosis.”
As well as increasing the volume of the initial sample provided, the intervention of sputum-submission guidance also aimed to improve case detection rates by increasing the likelihood of women returning with an early morning sample, and increasing the quality and volume of this second sample.
The authors believe one of their study’s strengths is that it was a pragmatic randomised trial, conducted in real, resource-restrained conditions. The cost per extra case detected was around $2. They say: “The intervention was designed to be cheap and easily replicable in low-income countries.”
They conclude: “Sputum submission guidance might be a highly cost effective intervention to improve smear-positive case detection and reduce the disparity between the sexes in tuberculosis control in low-income countries.”
In an accompanying comment, Dr Bachti Alisjahbana, Medical Faculty, Padjadaran Univeristy, Hasan Sadikin Hospital, Bandung, Indonesia, and Dr Reinout van Crevel, Radbound University Nijmegen Medical Centre, Nijmegen, Netherlands, say: “Khan and colleagues’ study is relevant for public health because it is also a pragmatic trial. Pragmatic or practical trials obtain scientific evidence for decision making in health care by measuring effectiveness (“does it work"”) rather than efficacy (“can it work"”).”
They conclude: “Combination of this intervention with others, such as education of health professionals or use of more-sensitive diagnostic methods, might further improve diagnosis of tuberculosis.”
Journal
The Lancet