Progress towards the End TB Goals in South Africa: A comparative cost-effectiveness analysis of tuberculosis interventions

While scaling up interventions under South Africa's 2023-2028 National Strategic Plan is highly cost-effective and will significantly reduce TB incidence and mortality, it falls short of meeting the 2030 End TB targets, necessitating further efficiency improvements and the development of new tools like low-cost diagnostics and vaccines.

The Gist

Imagine South Africa is trying to put out a massive, stubborn fire: Tuberculosis (TB). This fire has been burning for a long time, fueled by a dangerous partner, HIV, and it's been hard to control. The government has a "Firefighting Plan" (the National Strategic Plan, or NSP) with a goal to put out 80% of the fire by 2030.

This paper is like a team of expert engineers running a giant computer simulation to see if their current plan will work, how much money it will cost, and if they need to try something more extreme.

Here is the breakdown of their findings in simple terms:

1. The Current Plan vs. The Goal

The researchers ran a simulation from 2023 to 2042.

• The Goal: Reduce new fires (incidence) by 80% and deaths (mortality) by 90% compared to 2015 levels.
• The Reality Check: Even with the government's best-laid plan (the NSP), they will only reduce new fires by about 44% and deaths by 55%.
• The "Super-Plan" Test: The researchers also tested two "super-aggressive" scenarios.
  • Scenario 1: Checking every adult's symptoms four times a year, door-to-door.
  • Scenario 2: Checking every adult's lungs with a digital X-ray every year, door-to-door.
  • Result: Even these extreme measures only got them to about 57% reduction in fires and 75% reduction in deaths. They still missed the 2030 goal.

2. The Cost of Fighting the Fire

The researchers looked at the price tag for these plans.

• The Standard Plan (NSP): This would cost about 57% more than what they are currently spending. Over 20 years, it saves 6.6 million years of life. For every year of life saved, it costs about $308. This is considered a "good deal."
• The Super-Plans: These get very expensive very fast.
  • Scenario 1 costs 3 times more than the baseline.
  • Scenario 2 costs 15 times more than the baseline.
  • While they save more lives, the price per life saved jumps to $3,774 in the most extreme scenario. It's like buying a Ferrari to drive to the grocery store; it works, but it's not efficient.

3. Which Tools Work Best? (The "Magic Wands")

The study tested different tools to see which ones saved the most lives for the least money.

• The Free Wins (Cost-Saving):
  • Giving preventive medicine to people with HIV: This actually saves money because it stops people from getting sick in the first place.
  • Testing people who show up at clinics with coughs: Using the Xpert machine (a fast TB test) on anyone with symptoms is also a money-saver. It's like fixing a leak before the whole house floods.
• The Best Value Buys:
  • Checking family members: If someone in the house has TB, testing and treating their family members is very cheap and effective (about $12–$106 per life saved).
  • Making sure people start treatment: If someone is diagnosed but runs away before starting medicine, the fire keeps burning. A program to make sure they start treatment immediately is highly effective ($13 per life saved).
• The Expensive, Low-Yield Tools:
  • Door-to-door symptom checks and X-rays for everyone: These were the least efficient. They found very few extra cases compared to the massive cost. It's like sending a search party to look for a lost coin in a stadium when you know it's likely in your pocket.

4. Why Didn't They Reach the Goal?

The paper concludes that the current tools and strategies, even when used perfectly, aren't strong enough to reach the 2030 targets.

• The "Missing Pieces": The authors say we need new tools that don't exist yet, like a TB vaccine or cheaper, faster diagnostic tools.
• The "Hidden Fuel": The fire is also fed by things like smoking, alcohol use, diabetes, and poor nutrition. The current plan doesn't fully address these.
• The "Hard-to-Reach" Groups: The fire is burning hottest in men, but the current system isn't reaching them effectively.

The Bottom Line

South Africa's plan to fight TB is a solid step forward and will save millions of lives. However, it's like trying to win a race with a bicycle when the finish line requires a rocket ship. To actually win the race (reach the 2030 goals), the country needs to:

1. Use the current tools more efficiently (focus on family contacts and HIV patients).
2. Wait for or invent new, cheaper tools (vaccines and better tests).
3. Address the root causes like poverty and other health issues.

Without these new ingredients, the goal of an 80% reduction by 2030 will likely remain out of reach.

Technical Summary

Technical Summary: Progress towards the End TB Goals in South Africa

Problem Statement
South Africa faces a high burden of drug-susceptible (DS-TB), drug-resistant (DR-TB), and HIV-associated tuberculosis, contributing significantly to the global TB epidemic. Despite progress between 2009 and 2019 driven by antiretroviral therapy (ART) and intensified screening, the COVID-19 pandemic reversed these gains. The country aims to meet the World Health Organization's "End TB Strategy" targets: an 80% reduction in TB incidence and a 90% reduction in TB mortality by 2030 (relative to 2015 levels). However, there is a critical need to evaluate whether the interventions outlined in the 2023–2028 National Strategic Plan (NSP) are sufficient to meet these targets, to determine the required budget, and to assess the cost-effectiveness of scaling up specific interventions versus more aggressive, hypothetical screening scenarios.

Methodology
The study utilized the Thembisa TB transmission model, a deterministic compartmental model calibrated to South African local data (including vital registration, treatment initiation, HIV prevalence, and microbiological testing data). The model integrates DS-TB, DR-TB, and the HIV epidemic dynamics.

• Scenarios Evaluated:

  1. Baseline: Current TB programme interventions without improvement.
  2. NSP Scenario: Scaling up interventions aligned with the 2023–2028 National Strategic Plan. This includes expanded TB preventive therapy (TPT) for people living with HIV (PLHIV) and household contacts, symptom screening at primary health clinics, Xpert testing, targeted universal testing for TB (TUTT) in high-risk groups (PLHIV, household contacts, prior TB patients), and reduced initial loss-to-follow-up (ILTFU).
  3. Max Scenario 1: An aggressive hypothetical scenario involving quarterly door-to-door symptom screening for all adults and reduced loss-to-follow-up.
  4. Max Scenario 2: A highly aggressive scenario involving annual door-to-door digital chest X-rays for all adults, TPT for household contacts, and TUTT for contacts.

• Cost and Effectiveness Analysis:

  • Perspective: Provider (South African government).
  • Time Horizon: 2023–2042 (20 years).
  • Costs: Derived from the National TB Cost Model, adjusted to 2023/24 public-sector values and converted to USD.
  • Outcomes: Incremental cost per life year saved (LYS), per new active TB case averted, and per disability-adjusted life year (DALY) averted.
  • Sensitivity Analysis: One-way sensitivity analyses were conducted on unit costs (±50%) and the sterilizing efficacy of 3HP preventive therapy (varied from 10% to 90%).

Key Contributions
This study updates the 2016 TB Investment Case for South Africa, addressing previous gaps by using a comprehensively integrated TB-HIV model calibrated to local data rather than relying on external WHO estimates. It provides specific cost-effectiveness estimates for the full suite of interventions proposed in the current NSP and explores the theoretical limits of aggressive community screening.

Results

• Epidemiological Impact (2030 vs. 2015):

  • Baseline: Projected 35% reduction in incidence and 41% in mortality.
  • NSP Scenario: Projected 44% reduction in incidence and 55% in mortality.
  • Max Scenario 1: Projected 57% reduction in incidence and 75% in mortality.
  • Max Scenario 2: Projected 56% reduction in incidence and 71% in mortality.
  • Conclusion: Even under the most aggressive screening scenarios, the 80% incidence and 90% mortality reduction targets are not met.

• Cost-Effectiveness of Individual Interventions (NSP):

  • Cost-Saving: Xpert testing for symptomatic individuals seeking care and TPT for PLHIV.
  • Highly Cost-Effective: Symptom screening for household contacts ($12/LYS), ILTFU reduction ($13/LYS), TUTT for household contacts ($84/LYS), and TPT for household contacts ($106/LYS).
  • Less Cost-Effective: Community-based door-to-door screening and digital chest X-rays for asymptomatic adults showed modest impact and lower cost-effectiveness due to high unit costs and low yield in the general population.

• Budgetary Requirements (2023–2027):

  • Baseline: Average annual cost of ~$174 million.
  • NSP Scenario: Increases annual costs by 18% (reaching $284 million in 2027), totaling $1.28 billion over five years. Diagnostic interventions and treatment constitute the largest cost shares.
  • Max Scenarios: Max Scenario 1 requires a 329% cost increase ($3.7 billion total), while Max Scenario 2 requires a 1526% increase ($13.4 billion total), driven largely by the costs of mass screening (symptom screening and digital X-rays).

• Cumulative Impact (2023–2042):

  • The NSP scenario saves 6.6 million life-years at a cost of $308/LYS.
  • Max Scenario 1 saves 16.5 million life-years at $712/LYS.
  • Max Scenario 2 saves 14.6 million life-years at $3,774/LYS.

Significance and Claims
The paper concludes that while scaling up interventions to NSP coverage targets will substantially save lives and reduce morbidity, the End TB targets will not be met by 2030, even with the inclusion of additional aggressive screening scenarios. The authors state that accelerating progress requires a dual approach: improving the efficiencies of existing strategies (particularly targeting high-yield groups like household contacts and improving linkage to treatment) and developing new tools, specifically low-cost diagnostics and effective TB vaccines.

The study highlights that current community-wide screening strategies (door-to-door symptom checks and digital X-rays) are less cost-effective than targeted interventions due to high costs and low yields in the general population. It further notes that TPT for PLHIV is cost-saving but has a modest impact on overall incidence, suggesting a need to identify and target other high-risk groups, particularly those without HIV. The authors acknowledge limitations, including the lack of dynamic pediatric modeling and the exclusion of patient-level costs, but assert that their projections provide a robust basis for resource allocation decisions within the South African National TB Programme.