Multi-Factor Analysis of Single-Center Asthma Control in Xiamen, China

Clinical guidelines are systematically developed statements designed to help practitioners and patients make decisions regarding the appropriate health care for specific circumstances. Guidelines are based on the scientific evidence on therapeutic interventions. The first asthma guidelines were published in the mid 1980s when asthma became a recognized public health problem in many countries. The Global Initiative on Asthma (GINA) was launched in 1995 as a collaborative effort between the NHLBI and the World Health Organization (WHO). The first edition was opinion-based but updates were evidence-based. A new update of the GINA guidelines was recently available and it is based on the control of the disease. Asthma guidelines are prepared to stimulate the implementation of practical guidelines in order to reduce the global burden of asthma. Although asthma guidelines may not be perfect, they appear to be the best vehicle available to assist primary care physicians and patients to receive the best possible care of asthma.

Question What is the association between reductions in regional air pollutant concentration and incidence of childhood asthma? Findings In this longitudinal study that included 4140 children, each 4.3–parts-per-billion decrease in nitrogen dioxide was associated with a reduction of 0.83 cases per 100 person-years in asthma incidence; each 8.1-μg/m 3 decrease in particulate matter less than 2.5 μm was associated with a reduction of 1.53 cases per 100 person-years in asthma incidence. There were no statistically significant associations with change in ozone and particulate matter less than 10 μm. Meaning Declines in nitrogen dioxide and particulate matter less than 2.5 μm may be associated with decreased childhood asthma incidence. Importance Exposure to air pollutants is a well-established cause of asthma exacerbation in children; whether air pollutants play a role in the development of childhood asthma, however, remains uncertain. Objective To examine whether decreasing regional air pollutants were associated with reduced incidence of childhood asthma. Design, Setting, and Participants A multilevel longitudinal cohort drawn from 3 waves of the Southern California Children’s Health Study over a period of air pollution decline. Each cohort was followed up from 4th to 12th grade (8 years): 1993-2001, 1996-2004, and 2006-2014. Final follow-up for these data was June 2014. Population-based recruitment was from public elementary schools. A total of 4140 children with no history of asthma and residing in 1 of 9 Children’s Health Study communities at baseline were included. Exposures Annual mean community-level ozone, nitrogen dioxide, and particulate matter less than 10 μm (PM 10 ) and less than 2.5 μm (PM 2.5 ) in the baseline year for each of 3 cohorts. Main Outcomes and Measures Prospectively identified incident asthma, collected via questionnaires during follow-up. Results Among the 4140 children included in this study (mean [SD] age at baseline, 9.5 [0.6] years; 52.6% female [n = 2 179]; 58.6% white [n = 2273]; and 42.2% Hispanic [n = 1686]), 525 incident asthma cases were identified. For nitrogen dioxide, the incidence rate ratio (IRR) for asthma was 0.80 (95% CI, 0.71-0.90) for a median reduction of 4.3 parts per billion, with an absolute incidence rate decrease of 0.83 cases per 100 person-years. For PM 2.5 , the IRR was 0.81 (95% CI, 0.67-0.98) for a median reduction of 8.1 μg/m 3 , with an absolute incidence rate decrease of 1.53 cases per 100 person-years. For ozone, the IRR for asthma was 0.85 (95% CI, 0.71-1.02) for a median reduction of 8.9 parts per billion, with an absolute incidence rate decrease of 0.78 cases per 100 person-years. For PM 10 , the IRR was 0.93 (95% CI, 0.82-1.07) for a median reduction of 4.0 μg/m 3 , with an absolute incidence rate decrease of 0.46 cases per 100 person-years. Conclusions and Relevance Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 between 1993 and 2014 were significantly associated with lower asthma incidence. There were no statistically significant associations for ozone or PM 10 . This study uses Southern California Children’s Health Study data to examine associations between changes in regional air pollution (ozone, nitrogen dioxide, and particulate matter <10 μm and <2.5 μm) and changes in childhood asthma incidence across 3 child cohorts.

There has been no clear consensus about whether prenatal exposure to air pollution contributes to the development of wheezing and asthma in children. We conducted a systematic review to analyze the association between exposure to different pollutants during pregnancy and the development of childhood wheezing and asthma.