Unveiling spatial clusters of systemic sclerosis mortality in Spain: A comprehensive geographical analysis

Objectives: This study examined the spatial patterns of systemic sclerosis mortality in Spain from 2003 to 2022, identifying provincial-level clusters and sex-specific differences to explore potential underlying factors.

Methods: Mortality and population data (2003-2022) were sourced from the National Institute of Statistics. Age-standardized mortality rates were calculated, and spatial patterns were analyzed using standardized mortality ratios and smoothed relative risks via the Besag, York, and Mollié model, with statistical inference performed using the Integrated Nested Laplace Approximation (INLA) technique. Spatial clustering was assessed using Tango's and Kulldorff's tests.

Results: A total of 2016 SSc deaths were recorded, revealing a marked gender disparity. SSc mortality rates showed a consistent annual increase of 2.1% for both sexes, with women experiencing rates approximately 3.4 times higher than men. Age-specific analysis demonstrated higher mortality rates among women across all age groups, with an average sex ratio of 2.9, and rates increased with age for both sexes. Spatial analysis identified significant clusters of elevated SSc mortality in northwestern Spain, primarily in León and Asturias, with additional clusters extending to nearby provinces. These regions, characterized by silica mining and related industries, exhibited notable variations between men and women in the specific provinces affected.

Conclusions: This study identifies significant geographic and sex-based disparities in SSc mortality across Spain, with prominent clusters in the north. The results highlight the potential impact of environmental and occupational exposures on disease outcomes, emphasizing the need for targeted public health interventions in high-risk areas.