How Digital Scheduling Platforms Effect Insurance-Based Disparities in Access to Specialist Outpatient Care: A Cross-Sectional Audit Study in Berlin, Germany (Preprint)

<sec> <title>BACKGROUND</title> Digital appointment scheduling platforms have the potential to be widely adopted but may interact with insurance-driven incentives to amplify access inequities. In Germany’s dual insurance system, privately insured (PHI) patients may obtain earlier specialist appointments than statutory health insurance (SHI) patients. </sec> <sec> <title>OBJECTIVE</title> To quantify differences in wait times to first-available specialist outpatient appointments for SHI versus PHI profiles on a large commercial online scheduling platform (Doctolib) in Berlin, and to assess whether providers offering equal appointment options for both insurance types are deprioritized by the platform. </sec> <sec> <title>METHODS</title> We performed a cross-sectional internet-based audit between January 6 and February 26, 2025. Two standardized simulated patient profiles (SHI and PHI) were used to query 1,867 platform listings; providers with at least one bookable slot for both profiles were retained (n = 492). Primary outcome was wait time in days to the earliest available appointment. Paired t-tests compared within-provider wait times; subgroup analyses examined specialty-specific differences. Sensitivity analyses excluded the top 5% longest waits. Effect sizes (Hedges’ g) were computed. </sec> <sec> <title>RESULTS</title> Across 492 providers, mean wait times were 50.3 days (SD 52.2) for SHI and 22.6 days (SD 36.8) for PHI, yielding a mean difference of 27.7 days (95% CI 23.6–31.9; t(491) = 13.05; p &lt; .001; Hedges’ g = 0.59). After excluding the top 5% of wait times (n = 44), the difference remained significant (Δ = 23.1 days, 95% CI 20.0–26.2; t(447) = 14.77; p &lt; .001). The largest specialty gaps were observed in urology (Δ = 45.8 days; p &lt; .001), general surgery (Δ = 34.9 days; p = .012) and ENT (Δ = 31.6 days; p &lt; .001). Providers that offered earlier PHI appointments showed substantially longer SHI waiting times (61.8 vs 37.5 days; p &lt; .001) and substantially shorter PHI waits (12.0 vs 38.2 days; p &lt; .001). Platform ranking was correlated with earlier PHI availability (r = 0.574; p = 0.001), suggesting algorithmic amplification of differential access. </sec> <sec> <title>CONCLUSIONS</title> On this commercial scheduling platform in Berlin, SHI patients experienced substantially longer waits for first-available specialist appointments than PHI patients across multiple specialties. Platform ranking and differential slot allocation appear to amplify pre-existing insurance-based access inequities. Algorithmic transparency and insurance-neutral ranking criteria should be considered to promote equitable access. </sec> <sec> <title>CLINICALTRIAL</title> no registration </sec>