Program: SAFE strategy to control trachoma | GiveWell

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Program: SAFE strategy to control trachoma

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Published: 2009

In a nutshell

  • The Problem: Trachoma infection can lead to vision impairment and blindness.
  • The Program: Implementing a combination program known as the SAFE Strategy -- surgery, antibiotics distribution, facial cleaning (i.e., hygiene education), and environmental improvements (i.e., latrine building) -- to control trachoma and blindness.
  • Track record: There's strong evidence that surgery reduces trachoma trichiasis (the stage of trachoma that leads directly to blindness) and reasonably strong evidence that antibiotics distribution reduces infection rates. Evidence concerning the other program components is limited. The strategy has had large-scale success reducing prevalence of trachoma in 2 areas: Morocco and southern Sudan.
  • Cost-effectiveness: is difficult to assess because of limited information about different strategies' effectiveness. The estimates we have indicate that surgeries are relatively cost-effective ($100 prevents 1-30 years of blindness and another 1-30 years of low vision), while antibiotics treatment is not cost-effective.
  • Bottom line: The SAFE strategy is likely effective, although some components are better-established than others. We believe it is important that a charity implementing this strategy provide strong monitoring to continually assess effectiveness.

Basics of the program

What is the program? What problem does it target?

The World Health Organization recommends the SAFE Strategy (Surgery, Antibiotics, Facial cleanliness, and Environmental changes) to control trachoma.1 Trachoma is an infection that can lead to vision impairment and blindness as well as pain (see our writeup on trachoma).

What are the components required to implement this program - how does it work?

Each of the four parts of SAFE requires different components:

  • Surgeries require trained doctors to diagnose and perform surgeries.
  • Antibiotics distribution requires drugs and a distribution methods. Zithromax (azythromicin) is currently donated by Pfizer.2
  • Facial cleanliness requires
    • Educational materials to conduct training.
    • Materials needed for hygiene such as soap and clean water.
  • Environmental improvements require
    • Building materials for use in building latrines and other infrastructure.
    • Workers to complete construction.

Program track record

Micro evidence: Has this program been rigorously evaluated and shown to work?

There are no high-quality studies of the SAFE Strategy as a whole; available studies focus on each component individually.3

  • Surgery. Surgery can effectively abolish trichiasis,4 but recurrence post-surgery is significant (up to 20-40% by one year).5 There's no direct evidence that demonstrates that surgery reduces rates of blindness.6
  • Antibiotics distribution. A Cochrane review evaluated 15 high-quality studies, which in total included 8,678 participants, and concluded that "there is some evidence that antibiotics reduce active trachoma but results are not consistent."7

    Another review (by one of the co-authors of the review cited above) of antibiotics recognizes the limited evidence based on these studies, but explains the lack of evidence by observing that "these studies were conducted at a time when the standard practice was to only treat individuals with signs of active disease. This approach would have probably left a large pool of untreated infected individuals within a community to subsequently re-infect treated individuals, undermining the effectiveness of the intervention."8 In addition, two recent high-quality studies published subsequent to the Cochrane review found that treatment with antibiotics led to significant reductions in prevalence.9

  • Facial cleanliness. A Cochrane review found two high-quality studies, which in total included 2,560 participants, and concluded, "Current evidence does not ... support a beneficial effect of face washing alone or in combination with topical tetracycline in reducing active trachoma."10

    One study compared three pairs of villages and found a statistically significant effect for facewashing on reducing severe trachoma but not non-severe trachoma.11 Another compared eye washing and antibiotics to no treatment or antibiotics alone, and found no statistically significant benefit of eye washing.12

  • Environmental interventions. A Cochrane review evaluated four high-quality studies, which in total involved 10,356 participants, and concluded, "There is a dearth of data to determine the effectiveness of all aspects of environmental sanitation in the control of trachoma."13
    • Insecticide. "Two [high-quality] studies that assessed insecticide spray as a fly control measure found that trachoma is reduced by at least 55% to 61% with this measure compared to no intervention. However, another study did not find insecticide spray to be effective in reducing trachoma."14
    • Latrine provision. "One study found that another fly control measure, latrine provision, reduced trachoma by 29.5% compared to no intervention; this was, however, not a statistically significant difference."15
    • Health education. One "study revealed that health education on personal and household hygiene reduced the incidence of trachoma such that the odds of reducing trachoma in the health education village was about twice that of the no intervention village."16

Two less rigorous studies examined the effects of the SAFE strategy as a whole. Though both found drops in prevalence of the disease, the second study's results suggests that these drops could have been the result of other factors rather than the SAFE strategy:

  • A study in Tanzania followed "1,000 children less than eight years old ... in three randomly selected program villages."17 It found that the prevalence of active trachoma dropped from 39.2% to 32.7% and that the prevalence of severe trachoma dropped from 5.8% to 3.1% between the second and third years of a third year program."18 The study also reports that "these results are less dramatic than those observed in the program's first and second years," but does not provide numbers to support that claim.19
  • A study in Vietnam followed "1,200 children less than 15 years old from program villages receiving SAFE, the medical components of S and A, and from non-program villages."20
    • In villages receiving the SAFE intervention, prevalence fell from 8.4% at baseline to .7% at 24 months.
    • In villages receiving only the S and A components, prevalence fell from 11% at baseline 0% at 24 months.
    • In villages receiving no treatment, prevalence fell from 4.7% at baseline to .9% at 24 months.

Macro evidence: Has this program played a role in large-scale success stories?

Morocco: The Center for Global Development's Success Stories project cites the use of the SAFE strategy in Morocco as a major large-scale success story.21
Southern Sudan: An evaluation of four program sites with a total population of approximately 220,000 people was completed after three years of the SAFE Strategy.22 Active trachoma had fallen significantly in two areas, and slightly in the other two.23

Recommendations and concerns

What are the potential downsides of the intervention?

The sources we consulted do not discuss potential downsides.

Cost-effectiveness

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.

We have relatively little information about the likely impact of this program, so it's difficult to estimate the cost-effectiveness.

The Disease Control Priorities in Developing Countries report estimates that surgeries cost $4-82 per disability-adjusted life-year (DALY) averted. Antibiotics are estimated as being less cost-effective, in the range of $4,000 per DALY averted.24 These estimates imply that surgery is relatively cost-effective while antibiotics are not at all cost-effective.25 (More on the DALY metric.)

Using a simple conversion calculation, we estimate that $100 prevents 1-30 years of blindness and an additional 1-30 years of low vision when spent on surgeries (though insignificant benefits, in these terms, when spent on antibiotics). The source of the Disease Control Priorities in Developing Countries report's estimate is unclear and these figures should be taken with extreme caution.

Sources

  • 1.

    "A global initiative to eliminate trachoma as a blinding disease, entitled GET 2020 (Global Elimination of Trachoma), was launched under WHO's leadership in 1997. Through this initiative control activities are instituted through primary health care approaches that follow the evidence-based “SAFE” strategy. This consists of lid surgery (S), antibiotics to treat the community pool of infection (A), facial cleanliness (F); and environmental changes (E). VISION 2020 national plans that address trachoma are written in line with the GET 2020 'SAFE' strategy and recommendations." World Health Organization, "Priority Eye Diseases: Trachoma."

  • 2.

    Pfizer, "International Trachoma Initiative."

  • 3.

    "There are no clinical trials of the full SAFE strategy for trachoma control on blindness prevention, or on reducing active trachoma, or ocular Chlamydia trachomatis infection. However, there is some evidence that separately supports each of the components of SAFE: surgery, antibiotics, facial cleanliness, and environmental improvements." Sumamo 2007, Pg 943.

  • 4.

    "Evidence from case series and randomised controlled trials suggests that upper lid surgery is successful at abolishing trichiasis (Bog 1993; Bowman 2000a; Reacher 1992a)." Yorston et al. 2006, Pg 5.

  • 5.

    "Up to 20% to 40% of eyelids suffer from recurrence by one year (Bog 1993; Reacher 1990a; Reacher 1992a; Ward 2005)." Yorston et al. 2006, Pg 5.

  • 6.

    "No trials show interventions for trichiasis prevent blindness. Certain interventions have been shown to be more effective at eliminating trichiasis." Yorston et al. 2006, Pg 2.

  • 7.

    Mabey 2005, abstract.

    Additionally, "For the comparisons of oral or topical antibiotic against placebo/no treatment, the data are consistent with there being no effect of antibiotics but are suggestive of a lowering of the point prevalence of relative risk of both active disease and laboratory evidence of infection at three and 12 months after treatment." Mabey 2005, Pgs 1-2.

  • 8.

    Burton 2007, Pg 110.

  • 9.

    "Azithromycin was directly compared with topical tetracycline in several trials and found to be equally effective. In the largest of these studies (ACT) conducted in three endemic countries, mass communitywide treatment produced a marked reduction in the prevalence of chlamydial infection, which was sustained for 12 months of the study. Similar responses have been observed in subsequent studies." Burton 2007, Pg 110. Citing:

    • Schachter, J., et al. 1999. Azithromycin in control of trachoma. Lancet 354: 630–635. (Included in Mabey 2005)
    • Burton, M.J., et al. 2005. Re-emergence of Chlamydia trachomatis infection after mass antibiotic treatment of a trachoma-endemic Gambian community: a longitudinal study. Lancet 365: 1321–1328. (Subsequent to Mabey 2005)
    • Solomon, A.W., et al. 2004. "Mass treatment with single-dose azithromycin for trachoma." N Engl J Med 351: 1962–1971. (Subsequent to Mabey 2005)
  • 10.

    Ejere, Alhassan, and Rabiu 2004, Pg 2.

  • 11.

    "Face washing combined with topical tetracycline was compared to topical tetracycline alone in three pairs of villages in one trial. The trial found a statistically significant effect for facewashing combined with topical tetracycline in reducing 'severe' active trachoma compared to topical tetracycline alone. No statistically significant difference was observed between the intervention and control villages in reducing ('non-severe') active trachoma." Ejere, Alhassan, and Rabiu 2004, Pg 1.

  • 12.

    "Another trial compared eye washing to no treatment or to topical tetracycline alone or to a combination of eye washing and tetracycline drops in children with follicular trachoma. The trial found no statistically significant benefit of eye washing alone or in combination with tetracycline eye drops in reducing follicular trachoma amongst children with follicular trachoma." Ejere, Alhassan, and Rabiu 2004, Pgs 1-2.

  • 13.

    Rabiu 2007, Pg 2.

  • 14.

    Rabiu 2007, Pg 1.

  • 15.

    Rabiu 2007, Pgs 1-2.

  • 16.

    Rabiu 2007, Pg 2.

  • 17.

    Kumaresan and Mecaskey 2003, Pg 26.

  • 18.

    Kumaresan and Mecaskey 2003, Pg 26.

  • 19.

    Kumaresan and Mecaskey 2003, Pg 26, Table 3.

  • 20.

    "Data on active disease in Vietnam in areas implementing the full SAFE strategy, surgery and antibiotics alone, and in control villages are summarized in Table 4. The sample consisted of approximately 1,200 children less than 15 years old from program villages receiving SAFE, the medical components of S and A, and from non-program villages." Kumaresan and Mecaskey 2003, Pgs 26-27.

  • 21.

    "Between 1997 and 1999, the program implemented a new strategy called SAFE (surgery, antibiotics, face washing, and environmental change), giving Morocco the distinction as the first national-level test of the 4-part strategy...overall, the prevalence of active disease in children under 10 has been reduced by 99 percent since 1997." Levine 2007. See also Khazraji 2002, Pg 52, which charts the significant decline in trachoma prevalence after the program was introduced. See also Kumaresan 2003, Pg 26, Table 2.

  • 22.

    Ngondi 2006, Pg 591, Table 2.

  • 23.

    Ngondi 2006, Pg 592, Table 4.

  • 24.

    Jamison et al. 2006, Pg 954, Table 50.1.

  • 25.

    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.