Incidence of chronic obstructive pulmonary disease and risk factors in the Suzhou cohort / 中华流行病学杂志

Objective: To understand the incidence of chronic obstructive pulmonary disease (COPD) in the Suzhou cohort, and explore the risk factors for the development of COPD in Suzhou, and provide a scientific basis for COPD prevention. Methods: This study was based on the China Kadoorie Biobank project in Wuzhong District, Suzhou. After excluding individuals with airflow obstruction and self-reported chronic bronchitis, emphysema, or pulmonary heart disease at baseline, 45 484 individuals were finally included in the analysis. Cox proportional risk models were used to analyze risk factors of COPD and calculate hazard ratios and 95% confidence interval (CI) in the Suzhou cohort. The effect modifications of smoking on the association between other risk factors and COPD were evaluated. Results: Complete follow-up was available through December 31, 2017. Participants were followed up for a median of 11.12 years, and 524 individuals were diagnosed with COPD during the follow-up period; the incidence was 105.54 per 100 000 person-years. Multivariate Cox proportional risk regression models showed that age (HR=3.78, 95%CI:3.32-4.30), former smoking (HR=2.00, 95%CI:1.24-3.22), current smoking (<10 cigarettes/day, HR=2.14, 95%CI:1.36-3.35;≥10 cigarettes/day, HR=2.69, 95%CI:1.60-4.54), history of respiratory disease (HR=2.08, 95%CI:1.33-3.26), daily sleep duration ≥10 hours (HR=1.41, 95%CI:1.02-1.95) were associated with increased risk of COPD. However, education level of primary school and above (primary or junior high school, HR=0.65, 95%CI:0.52-0.81; high school and above, HR=0.54, 95%CI:0.33-0.87), consuming fresh fruit daily (HR=0.59, 95%CI:0.42-0.83) and consuming spicy food weekly (HR=0.71, 95%CI:0.53-0.94) were associated with reduced risk of COPD. Conclusions: The incidence of COPD is low in Suzhou. Older age, smoking, history of respiratory disease, and long sleep duration were risk factors for the development of COPD in the Suzhou cohort.

Change trend and prediction of lung cancer mortality in Suzhou in 2001-2020 / 公共卫生与预防医学

Objective To explore the epidemiological characteristics and trend of lung cancer mortality in Suzhou, to predict the future lung cancer mortality by ARIMA model, and to provide a scientific basis for the research of lung cancer prevention and control strategy. Methods The annual change percentage (APC) was used to analyze the annual change trend of lung cancer mortality from 2001 to 2020, and the ARIMA optimal model was employed to predict the lung cancer mortality from 2021 to 2025. Results The average annual crude mortality of lung cancer in Suzhou from 2001 to 2020 was 46.45/100 000, while the standardized mortality was 23.51/100 000. In recent 20 years, the crude mortality showed an upward trend and the standardized mortality showed a downward trend (APC crude rate = 2.51%, APC standardized rate = -0.78% , P < 0.001). The standardized mortality of lung cancer in men was 3.22 times that in women. The mortality of lung cancer in people over 45 years old increased with the increase of age, but the mortality in the 30-59 years old group showed a downward trend year by year. ARIMA model predicted that the annual trend of lung cancer crude mortality will tend to be flat in the next five years. Conclusion The crude mortality rate of lung cancer in Suzhou shows an upward trend, while the standardized mortality rate decreases year by year, suggesting that we should pay attention to the prevention and control of lung cancer in the elderly, accurately identify high-risk population of lung cancer, promote health publicity and education, carry out lifestyle intervention, and popularize the early screening of lung cancer.

Incidence of gastric cancer and risk factors in Suzhou cohort / 中华流行病学杂志

Objective: To describe gastric cancer incidence in Suzhou cohort, explore the environmental risk factors of gastric cancer in Suzhou, and provide appropriate suggestions for gastric cancer prevention and control. Methods: The participants were from the Suzhou cohort of China Kadoorie Biobank. Baseline survey was conducted from 2004 to 2008, followed by long-term follow-up until December 31, 2013. After the exclusion of those who had been previously diagnosed with peptic ulcer and malignant tumor reported at baseline survey and gastric cancer within six months after enrollment, a total of 50,136 participants were included. Cox proportional risk models were used to identify risk factors of gastric cancer and their hazard ratios in Suzhou. The effect modifications of gender on the association between risk factors and gastric cancer were analyzed. Results: In the follow-up of 7.19 years (median), 374 gastric cancers cases occurred. The standardized incidence was 94.57 per 100 000 person-years. Multivariate Cox proportional risk model analysis found that age (10 years old as a age group, HR=2.20, 95%CI: 1.92-2.53, P<0.001), current smoking (HR=1.84, 95%CI: 1.10-3.07 P=0.020), consumption of preserved vegetables weekly (HR=2.28, 95%CI: 1.28-4.07, P=0.005) and daily (HR=2.05, 95%CI: 1.16-3.61, P=0.013) were risk factors for gastric cancer. Female (HR=0.44, 95%CI: 0.25-0.76, P=0.003) and refrigerator use (10 years as a limit, HR=0.85, 95%CI: 0.74-0.97, P=0.016) were protective factors for gastric cancer. Further analysis showed that there was heterogeneity between males and females in the association between refrigerator use years and the incidence of gastric cancer (P=0.009), and there was an interaction effect between gender and refrigerator use on the incidence of gastric cancer (P=0.010). Conclusions: The incidence of gastric cancer in Suzhou cohort was high. The risk factors of gastric cancer varied. There was a synergistic interaction effect between gender and refrigerator use years on the incidence of gastric cancer.

Big-sized trees overrule remaining trees' attributes and species richness as determinants of aboveground biomass in tropical forests.

Large-diameter, tall-stature, and big-crown trees are the main stand structures of forests, generally contributing a large fraction of aboveground biomass, and hence play an important role in climate change mitigation strategies. Here, we hypothesized that the effects of large-diameter, tall-stature, and big-crown trees overrule the effects of species richness and remaining trees attributes on aboveground biomass in tropical forests (i.e., we term the "big-sized trees hypothesis"). Specifically, we assessed the importance of: (a) the "top 1% big-sized trees effect" relative to species richness; (b) the "99% remaining trees effect" relative to species richness; and (c) the "top 1% big-sized trees effect" relative to the "99% remaining trees effect" and species richness on aboveground biomass. Using environmental factor and forest inventory datasets from 712 tropical forest plots in Hainan Island of southern China, we tested several structural equation models for disentangling the relative effects of big-sized trees, remaining trees attributes, and species richness on aboveground biomass, while considering for the full (indirect effects only) and partial (direct and indirect effects) mediation effects of climatic and soil conditions, as well as interactions between species richness and trees attributes. We found that top 1% big-sized trees attributes strongly increased aboveground biomass (i.e., explained 55%-70% of the accounted variation) compared to species richness (2%-18%) and 99% remaining trees attributes (6%-10%). In addition, species richness increased aboveground biomass indirectly via increasing big-sized trees but via decreasing remaining trees. Hence, we show that the "big-sized trees effect" overrides the effects of remaining trees attributes and species richness on aboveground biomass in tropical forests. This study also indicates that big-sized trees may be more susceptible to atmospheric drought. We argue that the effects of big-sized trees on species richness and aboveground biomass should be tested for better understanding of the ecological mechanisms underlying forest functioning.

Tree crown complementarity links positive functional diversity and aboveground biomass along large-scale ecological gradients in tropical forests.

Most of the previous studies have shown that the relationship between functional diversity and aboveground biomass is unpredictable in natural tropical forests, and hence also contrary to the predictions of niche complementarity effect. However, the direct and indirect effects of functional diversity on aboveground biomass via tree crown complementarity in natural forests remain unclear, and this potential ecological mechanism is yet to be understood across large-scale ecological gradients. Here, we hypothesized that tree crown complementarity would link positive functional diversity and aboveground biomass due to increasing species coexistence through efficient capture and use of available resources in natural tropical forests along large-scale ecological gradients. We quantified individual tree crown variation, functional divergence of tree maximum height, and aboveground biomass using data from 187,748 trees, in addition to the quantifications of climatic water availability and soil fertility across 712 tropical forests plots in Hainan Island of Southern China. We used structural equation modeling to test the tree crown complementarity hypothesis. Aboveground biomass increased directly with increasing functional diversity, individual tree crown variation and climatic water availability. As such, functional diversity enhanced individual tree crown variation, thereby increased aboveground biomass indirectly via individual tree crown variation. Additional positive effects of climatic water availability and soil fertility on aboveground biomass were accounted indirectly via increasing individual tree crown variation and/or functional diversity. This study shows that tree crown complementarity mediates the positive effect of functional diversity on aboveground biomass through light capture and use along large-scale ecological gradients in natural forests. This study also mechanistically shows that tree crown complementarity increases species coexistence through maintenance of functional diversity, which in turn enhances aboveground biomass in natural tropical forests. Hence, managing natural forests with the aim of increasing tree crown complementarity holds promise for enhancing carbon storage while conserving biodiversity in functionally-diverse communities.

Climatic water availability is the main limiting factor of biotic attributes across large-scale elevational gradients in tropical forests.

Climatic water availability is a key spatial driver of species distribution patterns in natural forests. Yet, we do not fully understand the importance of climatic water availability relative to temperature, and climate relative to edaphic factors for multiple biotic attributes across large-scale elevational gradients in natural forests. Here, we modelled multiple abiotic factors (elevation, climate, and edaphic factors) with each of the taxonomic-related (Shannon's species diversity, species richness, species evenness, and Simpson's dominance) and tree size or biomass-related (individual tree size variation, functional dominance and divergence, and aboveground biomass) biotic attributes through boosted regression trees (BRT) models, using biophysical data from 247,691 trees across 907 plots in tropical forests in Hainan Island of Southern China. The tested multiple abiotic factors explained simultaneously 43, 50, 36, 45, 37, 50, 17 and 46%, respectively, of the variations in Shannon's species diversity, species richness, species evenness, Simpson's dominance, individual tree size variation, functional dominance, functional divergence and aboveground biomass. After the large influences of elevation (i.e. 30.43 to 62.83%), climatic water availability accounted for most (i.e. 15.52 to 25.30%) of the variations in all biotic attributes. Beside the increasing trend with elevational gradients, taxonomic diversity increased strongly with climatic water availability whereas tree size or biomass-related biotic attributes showed strong decreasing and increasing trends. Tree size or biomass-related rather than taxonomic-related biotic attributes also decreased apparently with mean annual temperature. Most of the biotic attributes monotonically increased with soil fertility but decreased with soil pH, whereas soil textural properties had mostly negligible influences. This study strongly reveals that future climate change (i.e. a decrease in climatic water availability with an increase in mean annual temperature) is thus likely to have a substantial influence on the biotic attributes in the studied tropical forests across large-scale elevational gradients.