WTW released its 30th annual Best Practices in Healthcare Survey on October 28, 2026, surveying 471 US employers with at least 100 employees, covering seven million workers. The headline is 11.1% projected 2027 health cost trend before plan changes, the steepest reading since the early 2000s. Pharmacy trend alone climbs to 11.5% in 2026 from 9% in 2025. GLP-1 coverage fell for the first time in three years, from 57% of employers to 53%.
The number that matters for a self-insured plan sponsor isn’t 11.1%. It’s the 86% of employers who told WTW that high-cost claimants, not pharmacy list prices, are their top cited cost pressure, ahead of the 83% citing pharmacy spend directly. That is a frequency story, not a unit-cost story, and it lands differently on a stop-loss aggregate corridor than a trend headline does.
Who It Affects
Self-insured employers of all sizes renewing stop-loss for January 1, 2027, plus the carriers and MGUs pricing aggregate attachments off this survey cycle. The GLP-1 pullback adds a second layer for any plan with members on weight-management therapy: 30% of employers still covering GLP-1s are weighing elimination, and 91% of those cite cost. Dropping coverage removes a pharmacy cost driver from the trend calculation, but it does not remove the comorbid conditions GLP-1s were treating, which can resurface as medical claims instead.
The Reserve Mechanism: Expected Claim Ratio
An aggregate stop-loss corridor is typically built from an expected claim ratio (ECR): a projected per-employee claims figure times enrollment, with the carrier’s trend assumption doing most of the work in that projection. A carrier that applies 11.1% as a flat multiplier to last year’s claims is modeling a unit-cost shift. But WTW’s own data says the pressure is concentrated in the frequency of high-cost claimants, the population already driving the catastrophic tail covered by specific stop-loss lasers, not a broad-based rise in everyday utilization.
That distinction changes where the risk sits. A flat-trend ECR smooths the increase evenly across the whole claim distribution. A frequency-driven increase concentrates it in the tail, exactly where aggregate corridors are thinnest relative to exposure. Plans whose brokers can’t say which assumption their carrier used this renewal are carrying risk they haven’t actually measured. The GLP-1 pullback compounds the ambiguity: it lowers projected pharmacy PMPM in the near term while leaving an open question about rebound comorbidity claims feeding back into the same high-cost-claimant bucket WTW just flagged as the primary driver.
What This Means for Your Next Review
Ask your broker or stop-loss carrier, in writing, whether this year’s aggregate attachment was priced off a flat trend percentage or a claimant-frequency model, and request the high-cost claimant count (members above $100,000 or $250,000 in annual claims) used in that pricing. If your plan is among the 30% weighing a GLP-1 exit, model the comorbidity rebound scenario before finalizing, not after the first stop-loss claim arrives. See What’s Actually Driving Your IBNR Higher? for the broader frequency-versus-severity diagnostic.
Sources
- WTW 2026 Best Practices in Healthcare Survey, StockTitan summary, October 28, 2026
- WTW press release, GlobeNewswire, October 28, 2026
- WTW, “Healthcare costs are rising. Is your strategy ready?”
- Insurance Business America, “Employers face 11.1% healthcare cost spike but balk at the fix,” October 28, 2026