Sources of Heterogeneity on Parameters of Dose-Response Relationship Between PM₁₀ and Short-Term Mortality by Meta Regression Method

Objective To identify the sources of heterogeneity on parameters of dose-response relationship between PM₁₀ daily concentration and mortality rate of certain diseases, so as to provide reference for transferring benefits among inter-city epidemiological studies.

Methods Epidemiological literatures on dose-response relationship between PM₁₀ daily concentration and mortality rate were collected by systematically searching China Journal Full-text Database(CJFD), PubMed database, and Elsevier Science Direct database. Stata 12.0 software was used to conduct single-factor and multi-factor meta regression analyses on the heterogeneity sources of the PM₁₀ induced short-time mortalities by disease categories.

Results Eleven literatures were finally included, covering 67 cities from China, USA, Europe, Latin America, and other Asia countries or areas. The results of meta regression analysis showed that factors such as PM₁₀ background concentration, temperature, humidity, proportion of population over 65 years old, and GDP per capita had significant effects on the dose-response relationship between PM₁₀ daily concentration and cardiovascular mortality rate. In cities with higher temperature and proportion of population over 65 years old as well as lower PM₁₀ background concentration, relative humidity, and GDP per capita, the increment of population-based cardiovascular mortality rate associated with each 10-μg/m³ increase of PM₁₀ compared to the background level was greater than that in the cities with corresponding factors skewed to the opposite direction. The results also showed that factors like PM₁₀ background concentration, temperature, and GDP per capita had significant effects on the dose-response relationship between PM₁₀ and respiratory mortality rate. In cities with higher temperature and lower PM₁₀ background concentration and GDP per capita, the increment of populationbased respiratory mortality rate associated with each 10-μg/m³ increase of PM₁₀ was greater than that in the cities with corresponding factors skewed to the opposite direction.

Conclusion The sources of heterogeneity on parameters of dose-response relationship between PM₁₀ and short-term mortality include PM₁₀ background concentration, temperature, relative humidity, proportion of population over 65 years old, and GDP per capita.