Pandemic-Associated Shifts and Spatial Inequality in Public Attention to Pulmonary Function Testing in China: A 14-Year Baidu Index Study

Background/Objectives: Pulmonary function tests (PFTs), especially spirometry, are important for chronic respiratory disease diagnosis and management, but Baidu-based online search interest in PFT-related information remains insufficiently characterized. This study examined long-term Baidu search activity for a selected PFT-related keyword in China from 2011 to 2024, with attention to pandemic-period changes, provincial variation, spatial inequality, and associated socioeconomic factors. Methods: We analyzed Baidu Index data from 1 January 2011 to 31 December 2024. The selected PFT-related keyword, “pulmonary function instrument,” was compared with “blood pressure monitor” and “blood glucose meter.” Daily Baidu Index values were aggregated into monthly and annual series. Temporal trends, relative search-intensity ratios, interrupted time-series analysis, inequality indices, fixed-effects regression, subgroup heterogeneity, and convergence dynamics were assessed. Results: PFT-related Baidu search activity remained lower than that for blood pressure and glucose monitoring, with relative search-intensity ratios below 0.35. Descriptively, PFT-related searches increased during 2020–2022; however, the re-specified seasonality-adjusted ITSA using unsmoothed monthly observations did not provide strong statistical evidence for an immediate level change at pandemic onset or a sustained slope change. Provincial differences persisted, with higher values generally observed in several eastern coastal provinces. Inequality indices were lower on average during 2020–2022 but fluctuated over time, and beta-convergence analyses provided limited statistical evidence of systematic catch-up among initially low-index provinces. Urbanization, per capita GDP, and population aging were positively associated with PFT-related Baidu Index values, while subgroup findings were interpreted as exploratory ecological associations. Conclusions: PFT-related Baidu search activity in China remained lower than search activity for blood pressure and glucose monitoring and showed persistent provincial variation. These findings suggest lower visibility of PFT-related information within the Baidu-based online environment.