All-payer claims databases (APCDs) comprise claims from multiple payers that can be traced to a single patient. To correctly estimate cost-sharing for an individual patient, we developed an algorithm to reconcile payments from secondary and tertiary payers to claims that are not fully covered by primary insurance. In a Colorado APCD cancer cohort (n = 70, 100), reconciliation of claims across multiple payers markedly lowered estimated cost-sharing for patients with more than one source of coverage (5, 544 (no reconciliation) ; 5, 013 (primary payer only) to 1, 580). The largest reductions in cost-sharing after reconciliation were for individuals with Traditional Medicare with Medigap (6, 449→1, 123; Δ = -5, 326), dual Medicare-Medicaid (4, 439→2, 340; Δ = -2, 099), and Medicaid-commercial (2, 708→2, 009; Δ = -699). Excluding secondary payments from estimates of cost-sharing systematically inflates cost-sharing estimates. A transparent reconciliation algorithm is necessary to correctly estimate cost-sharing and is recommended for researchers and policymakers who use the APCD for estimating costs across payers and to the patient.
DeVoss et al. (Tue,) studied this question.