High-cost claims: Bold strategies for smarter health plan management 

High-cost claimants pose an escalating challenge for employer health plans. As medical advances bring stunning new treatments to the market, we’ve seen rapid growth in the size and frequency of claims associated with a very small number of members. An analysis of health plan data in Mercer’s Compass data warehouse looked at members with claims in excess of $100k per year. While they accounted for just 1% of the 2.3 million members in the analysis, they drove 34% of total employer healthcare spend in 2025.  

While stop-loss coverage can help mitigate risk, many employers are finding it’s no longer enough. Unsurprisingly, “more focused management of high-cost claimants” is the top priority of large US health plan sponsors in their strategic planning for the next few years. In this post, we’ll discuss four areas where focused efforts can help employers rein in costs. 

1. Understand your data: Analyzing claims to gain clarity. 
You can’t fix what you can’t see, and traditional high-cost claimant reporting is no longer sufficient for plan management. The right data warehouse solution provides visibility into key cost drivers and gives you the ability to build clinical profiles of high-cost members. By pairing data with benchmarking tools and clinical support for claims interpretation, employers can identify members currently on a high-cost trajectory, target cost containment strategies, assess future risks, and forecast expenses for financial planning. 

2. Strategic oversight of medical specialty pharmacy and gene/cell therapies. 
Specialty infusions and injections such as biologics, cancer therapies, and gene/cell treatments administered in a provider setting are major, highly variable cost drivers. While carrier site-of-care programs aim to move treatment away from high-priced outpatient facilities, many medical specialty drugs, especially cancer therapies, are excluded — plus, a change in site of care doesn’t always guarantee lower pricing. Benchmarking can help identify cases with above-market pricing that can either be shifted to lower-cost settings or moved to PBMs without compromising outcomes. Carrier/vendor programs are increasingly targeting high-dollar outliers among maintenance chemotherapies and immunotherapies, which represent about 80% of the highest-cost injectables, to support cost containment. Employers should also consider ways to maximize utilization of centers of excellence for expensive gene and cellular therapies, both to ensure quality care and potentially to gain some financial protection through contracting. 

3. Take a peekaboo view into neonatal intensive care unit management. 
NICU admissions are at an all‑time high. The financial impact on employers is significant: NICU admissions consistently rank among the top five high‑cost claim categories and represents over half of all claims above $3 million according to Sun Life. Predicting NICU cases is difficult because maternity case management is often optional, and prenatal claim coding may not indicate elevated neonatal risk. Employers can improve visibility by collaborating with carriers to monitor authorizations and clinical signals in claims data, for example, prematurity or congenital anomaly diagnoses and neonatologist critical‑care claims. Early actions — clinical oversight to prevent discharge delays, pre‑payment review to catch billing errors and duplicates, case‑rate contracting, and targeted negotiation — can reduce costs, but it’s important that intervention occurs before facility bills are paid. Active engagement with your carrier is essential to determine what actions may be taken for each claimant. For one Mercer client, coordinated advocacy and carrier collaboration reduced a $17 million billed claim to an allowed amount of $4.4 million. 

4. Outlier inpatient stays. 
Lengthy, intensive inpatient admissions for conditions such as heart attack and sepsis can appear as erratic claim spikes. However, similar to NICU cases, these members can be identified early as emerging large claimants through utilization management and claims data indicators, such as repeated critical care procedure codes and diagnoses of multiple organ failure. This early identification can give your plan advance notice of catastrophic-level incoming claims. Management strategies before facility claims payment include clinical oversight to prevent discharge delays, pre-payment review of facility bills for errors and duplicates, and targeted negotiation. These pre-payment reviews — which AI can sometimes help with — and negotiations can yield savings of 20-30% in some cases. 

What’s the take-away for employer health plan sponsors? There are effective, proven strategies for mitigating the impact of high-cost claims. As these claims drive an ever-growing share of health plan costs, a focused cost management strategy — grounded in the experience of your own population — is more important than ever.