Profile of tuberculosis patients with delayed sputum smear conversion in the Pacific island of Vanuatu

Abstract

Global implementation of the DOTS strategy has resulted in a decline in tuberculosis (TB) incidence rates. 1 However, total patient numbers have not declined, and rates remain high in areas affected by human immunodeficiency virus (HIV) infection, poverty and drug-resistant TB. 2 Despite the adoption of the DOTS strategy in 1999-2000, progress towards global TB control targets has been slow in the Pacific region, with 16 534 cases (165 per 100 000 population) notified in 2011 compared to 4017 (68/100 000) in 1990. 1 TB remains a major public health threat in the region. The risk of Mycobacterium tuberculosis transmission is elevated in islands with a high population density, while vulnerability to developing TB is affected on one hand by malnutrition and food insecurity and on the other by rising rates of diabetes. 3 There has been growing concern over the possible emergence of drug-resistant TB in the Pacific. To date, 11 Pacific Island countries and territories have reported cases of multidrug-resistant TB (MDR-TB), but no formal prevalence surveys have been conducted. 1 A Pacific-wide supranational laboratory referral system was established in 2004 to provide ongoing surveillance for drug-resistant TB. 4 The Pacific TB laboratory (PATLAB) network links countries to reference laboratories where M. tuberculosis confirmation, strain typing and comprehensive drug susceptibility testing (DST) can be performed.Delayed sputum smear conversion has been identified as a risk factor for TB treatment failure and drug-resistant TB, 5,6 and may indicate prolonged infectiousness. Sputum smear status is typically recorded at the end of the intensive phase of treatment (i.e., after 2 months), and patients who still have smear-positive sputum at this time are regarded as delayed converters. In Vanuatu, there has been concern that TB incidence rates are not declining as expected and that increasing numbers of sputum smear-positive TB patients fail to convert to smear-negative within 2 months of treatment. However, the frequency of sputum non-conversion at 2 months and the profile of these patients have not been established.In the present study, we aimed to assess TB trends, compare the characteristics of 2-month non-converters (delayed converters) with those of converters and assess the potential contribution of drug-resistant TB. METHODS Study designThis retrospective cohort study included all sputum smear-positive TB cases who remained sputum smear-positive after 2 months of anti-tuberculosis treatment over a 9-year period (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012). For logistical reasons, 2-month sputum non-converters (delayed converters) were compared with those with smear conversion at 2 months (converters) diagnosed during 2011-2012. Results of specimens sent to the Supranational Reference Laboratory (SRL; Queensland Mycobacterium Reference Laboratory) in Brisbane, QLD, Australia, were reviewed to assess for drug-resistant TB. Study settingThe study was conducted in the Republic of Vanuatu, a Pacific Island na...

Delay in sputum smear conversion and outcomes of smear-positive tuberculosis patients: a retrospective cohort study in Bafoussam, Cameroon

“…Other potential explanations for non-conversion of sputum smear at the end of the intensive phase of TB treatment are: poor supervision of the initial phase of therapy, poor patient adherence, poor quality of anti-TB drugs, doses of anti-TB drugs below the recommended range, co-morbid conditions, drug-resistant M. tuberculosis that is not responding to first-line treatment and heavy initial bacillary load [ 4 ]. Heavy initial bacillary load has been documented (as in our study) as an important risk factor of delay in sputum smear conversion at the end of intensive phase of TB treatment [ 6 , 7 , 15 - 17 ]. So, to avoid non-conversion at the end of the initial phase of TB treatment, patients should be diagnosed early and treated.…”

Predictors of delayed sputum smear conversion among pulmonary tuberculosis patients in Kota Kinabalu, Malaysia

“…Our study is limited in that the assessment was based solely on information acquired from patient registers with some essential risk factor information such as the outcome of this study which is post-treatment smear grades missing from the MyTB system. Several studies had reported that at the end of the intensive TB treatment, heavy original bacillary load was recorded as a significant risk factor for delay in sputum smear transformation [44–47] . Future improvements or upgrade of MyTB should consider the inclusion of pre-treatment smear grades in the information system.…”

“…Several studies had reported that at the end of the intensive TB treatment, heavy original bacillary load was recorded as a significant risk factor for delay in sputum smear transformation. [44][45][46][47] Future improvements or upgrade of MyTB should consider the inclusion of pre-treatment smear grades in the information system. In addition, not all patients who were smearpositive had sputum culture results.…”

Predominant determinants of delayed tuberculosis sputum conversion in Indonesia

“…Research in Vanuatu found that an emphasis on patient education that encouraged treatment adherence improved sputum conversion among delayed sputum converters. [ 30 ] In addition, TB control programs should be integrated with programs to encourage patients to stop smoking, especially for TB patients with low levels of education who are young to adult smokers. TB control programs should also include treatment follow-up for TB patients with DM to ensure appropriate TB treatment.…”