Designing national programs for expanded carrier screening: Results from a discrete-choice experiment in Singapore

This study in Singapore utilized a discrete-choice experiment to determine that a national expanded carrier screening program would achieve the highest uptake and public preference if it offers multiple screening options, minimizes costs and wait times, and expands eligibility beyond married couples.

The Gist

Imagine you are planning a massive, nationwide "Health Check-Up Party" for future parents in Singapore. The goal of this party is to find out if couples carry hidden genetic "time bombs" (like thalassaemia or cystic fibrosis) that could make their future children sick. If they find out early, they can make informed choices to prevent these conditions.

But here's the problem: How do you design this party so that the most people actually show up?

This paper is like a menu design experiment. The researchers didn't just guess what people wanted; they asked 500 Singaporeans to play a game where they had to choose between different versions of this screening program. Think of it like ordering at a restaurant where you have to pick between three different meal deals, each with different prices, wait times, and menu sizes.

Here is what they discovered, broken down into simple concepts:

1. The "Price Tag" is the Boss

Just like when you shop for groceries, the cost was the biggest factor. If the "ticket price" (copayment) was high, fewer people wanted to come.

• The Analogy: Imagine a concert. If the tickets are free, the stadium is packed. If you charge $1,200 (a very steep price for a test), the crowd thins out significantly, though a good number still show up because the event is important.

2. The "Menu Size" Matters

People also cared about how many diseases were on the test.

• The Analogy: Would you rather have a tiny menu with just one dish, or a massive buffet with 100 options? Most people wanted the "buffet" (more diseases included) because it felt more thorough and valuable.

3. The "Waiting Room" Factor

Nobody likes to wait in line. The study found that long wait times were a turn-off.

• The Analogy: If you go to a food truck and the line is 2 hours long, you might walk away even if the food is free. People wanted their results quickly.

4. The "Choice" is Key

The study found that people liked having options.

• The Analogy: Imagine a school cafeteria that only offers one type of sandwich. Boring! But if they offer a "Basic Sandwich," a "Deluxe Sandwich," and a "Budget Sandwich," more students will eat there. The researchers found that offering a few different screening packages (instead of just one rigid rule) would bring in more families.

The Big Numbers (The "Bill")

The researchers crunched the numbers to see how much this would cost the government:

• If it's free: Almost everyone (85–90%) would sign up.
• If it costs $1,200: About 60–70% would still sign up (because people really want to protect their future kids).
• The Cost: Even with high participation, the total bill for the country wouldn't be astronomical (under $22.5 million a year), unless they decided to invite people who aren't currently married or planning to have kids right away.

The Takeaway

If Singapore wants to build a successful national program to catch these genetic risks early, the recipe for success is simple:

1. Keep the price low (or free).
2. Don't make people wait too long.
3. Give them a choice of packages.
4. Include more diseases on the list.

By treating the program like a customer-friendly service rather than a strict rule, the country can ensure that more future parents get the peace of mind they need.

Technical Summary

Technical Summary: Designing National Programs for Expanded Carrier Screening in Singapore

1. Problem Statement

Expanded carrier screening (ECS) for inherited genetic disorders (e.g., thalassaemia, cystic fibrosis, spinal muscular atrophy) offers a critical mechanism to reduce childhood morbidity and mortality. However, the success of national ECS programs hinges on high population uptake. In Singapore, there is a lack of empirical data regarding how operational factors—specifically cost structures, wait times, and the scope of disorders covered—influence the preferences of the reproductive-age population. Without understanding these drivers, policymakers risk designing programs with suboptimal uptake or unsustainable budget impacts.

2. Methodology

The study employed a Discrete Choice Experiment (DCE) to elicit stated preferences from the target demographic.

• Study Population: 500 Singaporeans of reproductive age (18–54 years).
• Experimental Design:
  • Attributes: Seven attributes were defined for a hypothetical national screening program, including suggested copayments, wait times, and the number of disorders included in the screening panel.
  • Tasks: Participants completed 30 choice tasks, each presenting 3 alternatives, divided into 3 blocks.
• Analytical Model: A Mixed Multinomial Logit (MMNL) model was utilized to estimate the utility of each attribute level and calculate the Willingness-to-Pay (WTP) for specific program features.
• Predictive Modeling:
  • Uptake Simulation: Predicted uptake was modeled for three plausible screening scenarios (Basic, Utility-Maximizing, and a third implied scenario) across a copayment spectrum ranging from $0 to $1,200 SGD (in $30 increments).
  • Budget Impact Analysis: Annual national budget impact was calculated based on an estimated 25,000 eligible couples per year. All financial figures were adjusted to 2026 SGD.

3. Key Contributions

• Quantification of Preferences: The study provides the first quantitative hierarchy of preferences for ECS attributes among Singaporeans, identifying cost as the primary driver, followed by the breadth of the screening panel and wait times.
• Policy Simulation Framework: It introduces a predictive framework that links specific program design parameters (copayments, panel size) to projected uptake rates and fiscal consequences.
• Strategic Insights on Choice Architecture: The research demonstrates that offering a menu of screening alternatives yields higher uptake compared to a single, mandatory program option, suggesting that flexibility is a key engagement tool.

4. Key Results

• Attribute Hierarchy: Respondents exhibited the strongest preference for cost (copayment), followed by the number of diseases included, and then wait times. Other attributes had limited statistical impact on decision-making.
• Uptake Sensitivity to Cost:
  • Zero Copayment: Predicted uptake ranged from 85% (Basic program) to 90% (Utility-maximizing program).
  • High Copayment ($1,200): Uptake dropped significantly to 61% (Basic) and 69% (Utility-maximizing).
  • Despite the decline, demand remained robust even at high price points, indicating a high baseline willingness to engage in screening.
• Budgetary Impact:
  • The annual budget impact is highly sensitive to eligibility criteria, copayment levels, and decision-making dynamics.
  • Under the modeled scenarios (restricted to married couples), the annual cost is unlikely to exceed $22.5 million SGD (95% CI: $19.0m –$26.6m).
  • Costs would rise substantially if eligibility were expanded beyond married couples.

5. Significance and Implications

This study offers a data-driven roadmap for the Singaporean government and healthcare planners to optimize national carrier screening programs.

• Maximizing Uptake: To achieve high participation rates, the study recommends minimizing copayments and reducing wait times.
• Program Design: Expanding the number of disorders in the screening panel and providing multiple screening options (rather than a "one-size-fits-all" approach) are critical strategies to align with public preferences.
• Fiscal Planning: The findings provide a realistic ceiling for annual budget allocation ($22.5m) under current eligibility constraints, aiding in sustainable long-term planning.
• Public Health Equity: By identifying that uptake remains high even with costs, the study suggests that financial barriers are manageable, but structural barriers (wait times, lack of choice) must be addressed to ensure equitable access for all prospective parents.