Epidemiological characteristics of fractures of spine, hip, proximal humerus and forearm during the haze epidemic period

Abstract

Background

Air pollutants have an impact on the occurrence of spine fractures, hip fractures, proximal humerus fractures and forearm fractures. This study aimed at evaluating the short-term impact of particulate matter with aerodynamic diameters of less than 2.5 µm (PM_2.5) on the occurrence of those fractures in Shijiazhuang, Hebei, China.

Methods

The daily meteorological, pollution, and fracture data of Shijiazhuang from 2014 to 2019 were collected. Distribution characteristics of fractures were described using descriptive epidemiological methods. The distributed lag nonlinear model (DLNM) was used to reveal the description of those fractures in the exposed and lag dimensions at the same time. Based on gender and age (<18 years old, 18-69 years old and >69 years old), stratified analysis was performed. Sensitivity analysis was performed to ascertain the robustness of the results.

Results

Between 2014 and 2019, fracture incidences in Shijiazhuang exhibited an overall increasing trend, with an obvious seasonality. PM_2.5 was positively related to daily fracture cases and the effects were more obvious in women, adolescents and people of working age. When PM_2.5 concentrations increased by one interquartile range (IQR) (70 μg/m³), RR exhibited a unimodal distribution. Its peak appeared on the 16^th day of lag (RR=1.005987, 95% CI:1.002472,1.009652), and the RRs were also statistically significant from the 10^th to 22^nd day of lag. Similarly, cumulative effects of each increase in the concentration of PM_2.5 IQR also showed a unimodal distribution. The largest cumulative effect occurred on the 28^th day of lag (RR=1.084457, 95% CI:1.012207,1.161864), and the cumulative RRs were also statistically significant from the 19^th day to 30^nd days. In the dose-response relationship, as PM_2.5 concentrations increased, RR increased.

Conclusion

Year by year, fractures in Shijiazhuang City exhibited an increasing trend. PM_2.5 can affect the occurrence of those fractures. The impact on women, adolescents and people of working age is even greater. The supervision of PM_2.5 should be strengthened while large-scale emissions should be limited.