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Tuberculosis (TB) is an infectious disease that frequently results in death (about 2/3 of the time for the more severe form of the disease, and 10-15% for the less severe form). (More on tuberculosis.)
DOTS refers to a broad TB control strategy outlined by the World Health Organization:1
DOTS is also sometimes used to refer more narrowly to "directly observed" tuberculosis treatment (i.e., the use of health workers to directly enforce compliance with drug regimens), but we use the term as the World Health Organization does.
There is no debate that the standard short-course chemotherapy regimen effectively cures TB.6 Because the treatment regimen lasts 6-8 months and many individuals do not strictly adhere to the treatment regimen,7 we focus here on whether interventions to improve access and adherence are effective. The evidence for the effectiveness of such efforts is primarily from national-level programs, discussed below.
DOTS has been credited with a number of large-scale, successful programs in the developing world to control TB. Below we summarize reports on China (Levine 2007) and Peru (Suarez et al. 2001).
In areas where the program was implemented, TB rates declined by 36%, and approximately 30,000 deaths have been averted each year.11 In western China, 5 provinces implemented DOTS and 7 did not. In the DOTS areas, TB rates declined by 33%; they only declined by 12% in non-DOTS areas,12 lending support to the idea that implementing DOTS, as opposed to other factors, caused a significant portion of the decline in TB.
The program had strong results. Between 1976 and 1990, reported cases of TB were relatively flat; they rose sharply between 1990 and 1993, possibly due to improved case detection in the early years of the program; and fell consistently from 1993 to 2000 (the last year the paper covers).16 Deaths from TB had been falling consistently since 1966 and fell slightly faster than this trend after the TB program was implemented.17 Suarez et al. (2001) estimates that 70% of deaths from smear-positive patients (those with the more severe form of the disease) were prevented between 1991 and 2000 because of Peru's program.18
As discussed above, a primary challenge of TB treatment is ensuring adherence to the treatment regimen. Approaches include:22
There is some evidence that approach #1 above achieves better results than standard directly-observed therapy. There is little evidence that other approaches are more effective.
The "DOTS" approach may help prevent the emergence of MDR-TB (multidrug-resistant TB).26 MDR-TB is a type of tuberculosis that "is resistant to at least two of the best anti-TB drugs."27 Were MDR-TB to emerge, it could be a major public health problem as treatment costs could be orders of magnitude higher than treating conventional TB.28
We have not done thorough cost-effectiveness analysis of this program. Because such analysis is highly time-consuming - and because the results can vary significantly depending on details of the context - we generally do not provide cost-effectiveness analysis for an intervention unless we find what we consider to be a strong associated giving opportunity.
We provide some preliminary figures based on the Disease Control Priorities in Developing Countries report, which we previously used for cost-effectiveness estimates until we vetted its work in 2011, finding major errors that raised general concerns.
The Disease Control Priorities in Developing Countries report states that cost-effectiveness varies with local factors;29 the range estimated for a sustained program is $5-$50 per disability-adjusted life-year (DALY) averted / $150-$750 per death averted.30 This places it among the most cost-effective programs.31 (More on the DALY metric.)
World Health Organization 2009b.
"Bacteriology remains the recommended method of TB case detection, first using sputum smear microscopy and then culture and drug susceptibility testing (DST), as indicated below...A wide network of properly equipped laboratories with trained personnel is necessary to ensure access to quality-assured sputum smear microscopy." World Health Organization 2009b.
"The treatment regimen recommended by the World Health Organisation includes at least three and preferably four specific antibiotics. They are called isoniazid, rifampicin, pyrazinamide and ethambutol. For convenience they may be given in a combination tablet which combines the antibiotics in a single tablet." TB Alert, "Frequently Asked Questions."
"In 2007, all of the 146 countries reporting data, including all HBCs, provided treatment with standardized short-course chemotherapy (SCC). There were 105 countries using the six-month Category I regimen and 23 countries using an eight-month regimen that does not include rifampicin in the continuation phase of treatment." World Health Organization 2009a, Pg 40.
"Directly observed therapy (DOT): an appointed agent (health worker, community volunteer, family member) directly monitors people swallowing their antituberculous drugs." Volmink and Garner 2007, Pg 3.
"Effective drugs for tuberculosis have been available since the 1940s." Volmink and Garner 2007, Pg 3.
"People with tuberculosis require treatment for at least six to eight months. Many find it difficult to complete their course of treatment and this serves as a major constraint to eradicating the disease (Fox 1958; Addington 1979; Cuneo 1989). Poor adherence to treatment can lead to prolonged infectiousness, drug resistance, relapse of tuberculosis, or even death. Incomplete treatment thus poses a serious risk for the individual as well as the community." Volmink and Garner 2007, Pg 3.
"In 1990, according to vital registration data, 360,000 people died from TB, making it the leading cause of death among adults." Levine 2007, Pg 3.
"In 1991, with $58 million in financial support from the World Bank, China embarked on a 10-year Infectious and Endemic Disease Control (IEDC) project to help curb its TB epidemic in 13 of its 31 mainland provinces. The project adopted the DOTS strategy and short-course chemotherapy." Levine 2007, Pg 3.
"Free diagnosis was offered, and patients' lungs were examined with chest fluoroscopy...New patients with smear-positive pulmonary TB were started on a course of directly observed treatment of antibiotics, every other day for at least two months and up to six months...Quarterly reports summarizing the case findings, treatment outcomes, and other program activities were submitted from each county to the province, the central government, and the newly formed National Tuberculosis Project Office, allowing for consistent monitoring of the project." Levine 2007, Pg 4-5.
"From 1990 to 2000, the number of people with TB in the DOTS area declined by 36.1 percent, about 4.1 percent each year, compared with a decline of 3.1 percent in non-DOTS areas...Since DOTS was introduced in China, more than 1.5 million patients have been treated, and approximately 30,000 TB deaths have been prevented each year." Levine 2007, Pg 5.
"In western China, for example, where five provinces implemented DOTS and seven provinces did not, the prevalence in the DOTS area decreased by 33.3 percent while the prevalence in the non-DOTSarea decreased by just 11.7 percent." Levine 2007, Pg 5.
"In August 1990, the National Tuberculosis Control Program (NTP) in Peru was revised, and the revised NTP (RNTP) follows the WHO DOTS strategy." Suarez et al. 2001, Pg 473.
"The main tenets of TB control under the RNTP are early case detection and diagnosis, followed by DOT of patients." Suarez et al. 2001, Pg 473.
"DOT is provided by nursing staff in special areas within health facilities reserved for this purpose. Patients are encouraged to come for treatment by being given food packages and employment support (e.g., training in handicrafts), and their transport costs are paid." Suarez et al. 2001, Pg 474.
"The number of reported pulmonary TB cases per capita remained roughly steady between 1976 and 1990 after an earlier decline (figure 2)...The case report rate increased sharply between 1990 and 1993, coincident with the improvement in diagnostic effort. Since 1993, reported new smear-positive cases have declined in all departments of the country (figure 3A)." Suarez et al. 2001, Pg 475.
Suarez et al. 2001, Pg 475, Figure 2.
"This elevated rate of decline suggests that 27% (19%–34%) of cases (158,000) and 70% (63%–77%) of deaths (91,000) among smear-positive patients were averted between 1991 and 2000." Suarez et al. 2001, Pg 473.
"Poor adherence to treatment can lead to prolonged infectiousness, drug resistance, relapse of tuberculosis, or even death. Incomplete treatment thus poses a serious risk for the individual as well as the community." Volmink and Garner 2007, Pg 3.
"The biggest resurgences of TB in recent history have been driven by the spread of HIV in Africa and are linked to the rise of drug resistance in former Soviet republics." Jamison et al. 2006, Pg 299.
"Can the TB treatment cause side effects? Rifampicin will turn urine and other body secretions such as tears orangy-red. It also interacts with other medicines, in particular it reduces the effectiveness of the contraceptive pill. It is therefore important to warn your doctor when prescribing other medicines that you are on TB treatment.
The tablets may rarely cause some of these:
TB Alert, "Frequently Asked Questions."
Unless otherwise noted, the following list is quoted from Vomink and Garner 2007, Pg 3.
Liu et al. 2008, Pg 2.
Bosch-Capblanch et al. 2007, Pg 2.
"Disease Control Priorities for Developing Countries" reports some evidence of this: "Observations on the way DOTS is presently implemented suggest that a ceiling on case detection might be reached at about 50 to 60 percent (Dye and others 2003; WHO 2005). This fraction is about the same as the percentage of all cases reported annually to WHO from all sources (that is, from DOTS and non-DOTS programs). The problem is that, as DOTS programs have expanded geographically, they have not yet reached far beyond existing public health reporting systems." Jamison et al. 2006, Pg 294.
"Relatively simple, the DOTS approach can improve patient compliance, cure the vast majority of new TB patients, and prevent transmission of the disease and the emergence of MDR-TB (Balasubramanian, Oommen, and Samuel 2000; Dye and others 2002)." Jamison, et al. 2006, Pg 1041.
CDC, "Tuberculosis: Fact Sheet."
"Because many patients either are treated outside the DOTS regimen or do not adhere to the long-term chemotherapy necessary to eradicate the causative organism,MDR-TB is likely to emerge and treatment costs are likely to escalate to as high as 1,000 times the cost of conventional treatment of drug-sensitive infection." Jamison, et al. 2006, Pg 1041.
"The cost effectiveness of TB control depends not only on local costs but also on the local characteristics of TB epidemiology (for example, epidemic or endemic, low or high rates of HIV infection and drug resistance) and on the rate of application of any chosen intervention." Jamison et al. 2006, Pg 301.
"For a 10-year program of treatment for infectious TB, the cost per death prevented is typically US$150 to US$750, and the cost per DALY gained is US$5 to US$50 for all regions except Europe and Central Asia (figure 16.1)." Jamison et al. 2006, Pg 299.
See Jamison et al. 2006, Pgs 41-42, Figures 2.2 and 2.3 for a chart of the cost-effectiveness range (measured in cost per DALY) for many programs.