Better Evidence Starts With the Right Claims Data Source

Real-world evidence can help biopharma teams better understand patient populations, care patterns, healthcare resource utilization, disease burden, and outcomes. But the value of that evidence depends on whether the data source is fit for the question being asked.

That question was central to Magnolia Market Access research presented at ISPOR 2026. The poster, Comparability of Closed and Open Claims Data for Healthcare Resource Utilization Assessment in Acute Ischemic Stroke, compared open and closed claims data among patients with persistent upper extremity deficit following acute ischemic stroke. The objective was to assess healthcare resource utilization captured in open claims compared with closed claims data.

The findings point to a practical challenge in evidence planning: open and closed claims data are both valuable, but they have different strengths.

Open claims can offer broader coverage, larger patient counts, and more timely visibility into patient interactions across settings and payers. In the ISPOR 2026 analysis, open claims identified more than 10 times the number of acute ischemic stroke admissions compared with closed claims and showed generally similar rates of baseline comorbid conditions.

The scale and timeliness of open claims can be useful when teams need directional visibility into patient activity or utilization patterns. But scale alone does not determine whether a data source is appropriate for a specific evidence question.

Closed claims, by contrast, are generated from insurance providers and are tied to defined enrollment periods. This allows for a more complete longitudinal view of a patient’s care across settings over time. The ISPOR 2026 analysis found higher rates across follow-up outcomes in closed claims compared with open claims. These differences suggest that open claims may have incomplete capture over time, making them less reliable than closed claims for longitudinal outcomes analysis in this context.

When the data source does not match the question, teams risk over-interpreting findings or relying on evidence that may not fully support the decision at hand.

In practice, open claims can be especially useful for market sizing and trend analyses, particularly for rare conditions or newer treatments, where scale and timeliness are important. Closed claims may be more appropriate when the analysis requires continuous enrollment, longitudinal follow-up, or a more complete view of outcomes over a defined period.

The key is not to view one source as universally better than the other. It is to understand what each source can credibly support.

Magnolia Market Access helps biopharma teams evaluate these tradeoffs early. By aligning the evidence question, data-source selection, analytic approach, and market access objective, MMA supports more credible analysis across HEOR/RWE, Market Analytics, Value/Evidence Planning, and broader access strategy.

For teams planning a claims-based analysis, the goal should not simply be to find the largest dataset or the fastest dataset. The goal should be to select the data source that can credibly answer the question that matters most.

That same principle applies beyond claims data. As biopharma teams evaluate electronic health records, registries, lab data, patient-reported outcomes, chart reviews, and other real-world data sources, the strategic question remains the same: what evidence is needed, and which data source can credibly support it?

For market access and evidence planning teams, the value of real-world data is not just in having access to more information. It is in knowing how to use the right information, in the right context, to support decisions that affect access, evidence generation, and commercialization strategy.