How Online Scheduling Platforms Affect Insurance-Based Disparities in Access to Specialist Outpatient Care in Berlin, Germany: Cross-Sectional Audit Study.

Abstract

Online scheduling platforms are increasingly chosen by patients for scheduling outpatient appointments. Due to payment for listing or platform decisions on listing visibility, they can amplify access inequalities. Especially in Germany's dual insurance system, the beneficiary difference in waiting times for private health insurance (PHI) patients compared to statutory health insurance (SHI) patients for specialist appointments might increase. The objective of this study was to quantify differences in waiting times for the first available specialist outpatient appointments for SHI versus PHI profiles on a large commercial online scheduling platform (Doctolib) in Berlin and to assess whether practices offering equal appointment options for both insurance types are deprioritized by the platform. We performed a cross-sectional, internet-based audit between January 6, 2025, and February 26, 2025. Two standardized simulated patient profiles (SHI and PHI) were used to query 1867 platform listings; practices with at least 1 bookable slot for both profiles were documented (n=492). The primary outcome was the waiting time in days for the earliest available appointment. Paired 1-tailed t tests and Wilcoxon signed-rank tests were used to compare within-provider waiting times, while exploratory subgroup analyses examined specialty-specific differences. Sensitivity analyses excluded the top 5% of the longest waits. Effect sizes (Hedges g) were computed. Across 492 practices, mean waiting times were 50.4 (SD 52.2) days for SHI and 22.6 (SD 36.8) days for PHI, yielding a mean difference of 27.8 days (95% CI 23.6-31.9 d; t491=13.05; P<.001; Hedges g=0.59). After excluding the top 5% of waiting times (n=44), the difference remained significant (Δ=23.1 d; 95% CI 20.0-26.2 d; t447=14.77; P<.001). Providers that offered earlier PHI appointments showed substantially longer SHI waiting times (61.8 vs 37.5 d; P<.001) and substantially shorter PHI waits (12.0 vs 38.2 d; P<.001). Platform ranking was correlated with earlier PHI availability (Spearman rank correlation r=0.574; P<.001). On this commercial online scheduling platform in Berlin, SHI patients experienced substantially longer waits for the first available specialist appointments than PHI patients across multiple specialties. Potential mechanisms that could amplify pre-existing insurance-based access inequities are discussed. Transparency about the platform's ranking criteria should be considered to promote equitable access.