HOS 101: The Health Outcomes Survey and its importance for Medicare

Medicare Advantage (MA) plans and their members are two sides of the same coin, each with a vested interest in ensuring that coverage is up to snuff. On one side, members wonder, “Will my prescriptions be covered? Can I afford a necessary procedure?” On the other, plans need to know they’re offering benefits that will attract and retain members. Each uses various methods to assess Medicare Advantage plans, whether that means members looking at coverage options or plans adding up costs. 

One measure that impacts Medicare as a whole? The Health Outcomes Survey (HOS), which sets a benchmark for how MA plans impact member health. Explore how the HOS provides valuable data—and what recent Medicare changes mean for its application. 

Understanding the basics of the Health Outcomes Survey (HOS)

Is your Medicare Advantage plan living up to members’ expectations? Sometimes the best way to find out is to ask! The Health Outcomes Survey makes this easy because it’s based on patient-reported insights and outcomes.

The HOS helps plans and members alike. The survey enables health plans to assess plan performance, monitor the health of the Medicare population, and evaluate treatment outcomes to identify areas for improvement. At the same time, members use the data to compare MA contracts and find the best fit for their needs. 

HOS methodology

The general premise is simple: to gather data—including physical and mental health, daily activities, and sleep patterns—from Medicare Advantage beneficiaries. The HOS selects a random sample of 1,200 MA plan participants each year, and respondents are surveyed again two years later. 

The survey uses two types of limited data sets (LDS) in its measurements to understand plans and members: 

• Baseline files with data collected during the annual survey
• Analytic files with merged baseline data and follow-up data from the resurvey two years later

But why twice? Follow-up surveys give plans the data they need to know to make meaningful changes. By comparing baseline and follow-up analytic data, a plan can assess its effectiveness in maintaining or improving member health.    

HOS timeline

The HOS is delivered on a specific timeline each year. From summertime all the way through to the shedding of fall leaves, members are selected, surveyed, and recontacted for additional data:

• July 15: Pre-notification letter mailed to all sampled members
• July 22: First questionnaire mailed with cover letter to members
• August 26: Second questionnaire with cover letter mailed to non-respondents
• September 16: First phone outreach attempt to non-respondents
• November 1: Additional phone outreach attempt to non-respondents (before) + Data collection officially closes (Nov 1 deadline)

Note that the HOS timeline also includes a blackout period eight weeks before and during the official CMS HOS and HOS-M survey administration. During this window—from May 24 – November 1—plans may not field any Survey questions.

The HOS helps both members and Star Ratings

Medicare Star Ratings help consumers compare health plans and providers based on quality and performance. The Centers for Medicare & Medicaid Services (CMS) rates MA plans on a five-star scale, factoring in 39 distinct measures across several categories:

• Domain measures (HEDIS, CAHPS, Operations, Pharmacy, HOS)
• Quality improvement (QI) measures x 2 (Part C, Part D)
• Categorical adjustment index (CAI) (Addressing disparities among low-income subsidy, dual eligible, and/or disabled beneficiaries)
• Reward factor (reward for consistently high performing contracts)*
• Health equity index (HEI) (reward for demonstrating disparity reduction in those with social risk factors)*

*Reward factor is the current measure, to be replaced by HEI in 2027 Star Ratings.

Star Ratings incorporate HOS measures

Medicare Part C Star Ratings look at five HOS measures, including functional health and HEDIS measures:

1. Monitoring physical activity
2. Improving bladder control
3. Reducing fall risks
4. Improving or maintaining physical health**
5. Improving or maintaining mental health**

**Measures are for display only in 2024 and 2025 Star Ratings.

While the latter two metrics do not currently impact Star Ratings, the results are included in each plan’s annual HOS Performance Measurement Report of adjusted scores from their baseline and two-year follow-up surveys. In 2026, these measures will be added to Star Ratings with the change in weights impacting the focus of health plans.

Why the HOS will matter in Medicare in 2025 and beyond

Both HOS and the Medicare system are fluid. CMS aims to drive health equity, improving measurement methods and holding plans to rigorous standards. A few key changes could make a difference in the coming years:

Frailty payments

Frailty adjustments account for Medicare expenditures of community populations with functional impairments. Medicare Advantage organizations planning to sponsor Fully Integrated Dual Eligible Special Needs Plans (FIDE SNPs) and seeking frailty payments must contract with an approved survey vendor to conduct the HOS and gather data to calculate frailty adjustments to the FIDE SNP risk scores. Frailty scores are based on HOS surveys from the year prior to the payment year. 

Enhancing HOS 

CMS is currently in the process of securing Office of Management and Budget (OMB) approval to evaluate new survey items and revised content to improve HOS measurement. A revised survey could include items that zoom in on various aspects of health not currently measured. 

• PROMIS physical function items: Questions from the PROMIS item banks assess additional functional impairments to enhance the physical functioning activities of daily living (PFADL) measure.
• Generalized anxiety disorder 2 (GAD-2) items: Questions measure anxiety to assess mental health beyond current HOS items centered on depression.
• Health-related social needs (HRSN) items: Questions assess unmet social needs related to SDOH to determine if plans are addressing these needs.

Making changes to HOS questions aims to eliminate items with minimal impact and introduce new ones to improve the value of the survey. Field testing these updates could inform formal updates, including factoring into Star Ratings.

Drive positive HOS results with Medicare support

The Health Outcomes Survey helps to unravel what’s right and wrong with Medicare, reflecting perceptions of care that can impact your plan’s rating. By measuring data over time, HOS provides a clearer picture of plan quality than a one-time, knee-jerk reaction from members, and it’s still evolving to become even more helpful.

Pyx Health offers innovative solutions to support the physical and mental health measures that stand to impact HOS and Star Ratings in the coming years. Our approach combines compassionate care from support staff who connect Medicare members with plan and community resources with evidence-based technology to elevate engagement, uncover and address SDOH needs, and improve outcomes.

Curious about how it works? Download our case study to learn how Pyx Health drives member outcomes and helps plans achieve their goals.