Sun Life’s 2026 High-Cost Claims and Injectable Drug Trends report, released May 21, analyzed more than 70,000 stop-loss claims from 3,300 self-funded employers and found that secondary health conditions, not primary diagnoses, are the dominant cost driver pushing claims above $3 million. For plan sponsors setting specific stop-loss deductibles based on primary diagnosis alone, the finding exposes a structural blind spot in catastrophic claim modeling.
The report’s headline number: million-dollar-plus claims increased 46% from 2022 to 2026. Blood cancer claims averaged $5.45 million in 2025, with the single highest leukemia claim approaching $8 million. Elevidys, the gene therapy for Duchenne muscular dystrophy, averaged $3.6 million per treatment. But the comorbidity finding is more consequential for renewal pricing than any single diagnosis.
Sun Life’s data identifies strong connections among cancer, cardiovascular disease, chronic kidney disease (CKD), and orthopedic conditions. These conditions share common risk factors: obesity, diabetes, and chronic inflammation. Liver disease treatment spending rose 43% in 2025, averaging $230,000 per patient. Osteoarthritis prevalence among dialysis patients hit 54%. When these secondary conditions layer onto a primary diagnosis, they compound inpatient stays, injectable drug costs, and total claim severity in ways that single-diagnosis risk models do not capture.
Claims involving GLP-1 medications rose 24% year over year, adding pharmacy spend on top of the underlying condition costs. That trend interacts directly with the comorbidity finding: GLP-1s target obesity, which links to the cardiovascular, CKD, and orthopedic clusters driving the highest-cost claims.
Who it affects
Self-insured employers in every sector that purchase specific stop-loss coverage, particularly those with specific deductibles between $250,000 and $500,000 where a single comorbid claimant can breach the attachment point multiple times in a policy year. Benefits directors and CFOs reviewing renewal exhibits should pay close attention to how their stop-loss carrier models tail risk above $3 million.
The reserve mechanism
The standard approach to stop-loss renewal underwriting segments expected claims by primary diagnosis. Sun Life’s data suggests this understates tail severity. When a cancer patient also develops CKD or cardiovascular complications, the claim trajectory shifts from the primary diagnosis distribution to a compounded severity curve that current models underweight.
This affects three variables in the IBNR calculation for self-funded health plans: the expected claim ratio above the specific deductible, the aggregate corridor adequacy, and the severity loading for large claims already in development. Plans that laser individual claimants based on their primary diagnosis may be missing the secondary-condition risk that actually drives the claim past the deductible.
What this means for your next review
At the next stop-loss renewal or reserve study, ask whether comorbidity clusters are modeled in the expected claim distribution above the specific deductible. Request a breakout of claims exceeding $1 million by the number of concurrent active diagnoses. If your TPA’s data extract captures only the primary ICD-10 code at the claim level, the secondary-condition severity is invisible to your actuary and your stop-loss carrier. Getting secondary diagnosis data into the extract is the first step toward pricing the risk you actually carry.