After a long period of decline, tuberculosis (TB) incidence and mortality in the Russian Federation rose dramatically in the 1990s and peaked in 2000. (1) During the same period, the proportion of notified TB patients cured by therapy fell precipitously from 90% in 1985 to an estimated 72% in 2000. Despite the Russian Federation's introduction and gradual uptake over the past decade of the DOTS strategy, treatment success rates have remained consistently low even though case notifications have declined. (2) WHO attributes these high failure rates to drug resistance and high rates of default and death among Russian patients receiving DOTS. (3)
Before addressing these problems to improve DOTS outcomes, it is necessary to identify the proximal causes of death, default and the acquisition of drug resistance among TB therapy patients. In an earlier study, we reported the causes of death of patients undergoing DOTS treatment in Tomsk, Siberia, from January 2002 to December 2003. (4) We observed a 9.6% death rate during TB treatment--due not only to TB but also to co-morbid conditions such as alcohol ism and cardiovascular disease. We also found that both alcoholism and late presentation contributed substantially to mortality.
Here, we present data on programmatic and individual risk factors for non-adherence, default and the acquisition of multidrug resistance (MDR) in a DOTS treatment cohort in Tomsk. Based on our findings, we propose several specific interventions that may improve treatment outcomes and reduce the acquisition of drug resistance in patients undergoing TB therapy in this setting.
Setting and programme description
We conducted this study in the Tomsk oblast of western Siberia, where the incidence and mortality rates for TB in 2001 were 109.3 and 18.3 per 100 000, respectively. Rates of MDR in Tomsk were among the highest reported worldwide; MDR among newly diagnosed patients rose from 6.5% in 1999 to 12.1% by 2002. In 1995 Tomsk was one of the first Russian Federation oblasts to implement the DOTS strategy.
Tomsk City TB Services (TTBS) oversees diagnosis, treatment and reporting of adult patients with TB. Suspects undergo sputum smear microscopy and culture at the time of diagnosis. Those who are culture-positive also undergo drug sensitivity testing to isoniazid, rifampicin, ethambutol, streptomycin and kanamycin. Susceptibility is determined using the absolute concentration method on Lowenstein-Jensen medium, based on the following drug concentrations: isoniazid 1 [micro]g/ml, rifampicin 40 [micro]g/ml, ethambutol 5 [micro]g/ml and streptomycin 10 [micro]g/ml. Massachusetts State Laboratory Institute, a supranational reference laboratory, provides external quality control.
Patients diagnosed with active TB are treated according to WHO recommendations. (5) Those with multidrug-resistant TB (MDR-TB) are switched to an individualized regimen based on the drug resistance profile. Treatment is offered three ways: under direct supervision in an inpatient setting, atone of three outpatient clinics or through home-based care. Patients receive drugs daily in each of the outpatient settings. Home-based care is provided for those who are unable to attend outpatient clinics, with nurses delivering drugs directly to the patients. Some patients self-administered drugs during weekends and holidays, and a small proportion self-administered over half of their medications. Government social services provide free passes for public transport to all patients treated in ambulatory settings. Travel expenses are not provided for patients who have no public transport services. Patients undergoing TB treatment are assessed with repeat sputum smear, culture and drug-sensitivity testing (DST) in months 2, 3 and 5 as well as at the end of treatment and at six-month intervals thereafter.
We conducted a retrospective cohort study of newly detected smear- and/or culture-positive TB patients aged over 17 who were notified under DOTS and began TB treatment during the period from 1 January to 31 December 2001. …