Spatial distribution combined cold and hotspots of China's healthy adult male serum CA19-9 reference value based on classification and regression tree / 西安交通大学学报(医学版)

Objective: To provide clinical criteria with regional basis of the reference values of carbohydrateantigen 19-9 (CA19-9) in healthy Chinese male adults. Methods: First, the reference values of CA19-9 in 9,382 healthy male adults distributed in 64 cities and counties in China were collected to construct the database. Then geographical factors received dimensionality reduction by comprehensive application of the principal component analysis, variation coefficient method, and correlation analysis; then the classification regression tree model was constructed. Third, the hotspot and spatial distribution of the reference values of CA19-9 in healthy male adults was drawn based on 2,322 observation data points. Results: The reference value of CA19-9 showed spatial variation, which was higher in the southern region than in the northern region, and higher in Jilin and Liaoning provinces than in the eastern central region. Hotspots were mostly distributed in the southern region, and cold spots in the northern region. Conclusion: There exist spatial variation of the reference values of CA19-9 at spatial level. Therefore, when it comes to clinical diagnosis, it is necessary to consider regional variation.