Modeling respiratory illnesses with change point: A lesson from the SARS epidemic in Hong Kong

Abstract It is generally agreed that respiratory disease is closely related to ambient air quality and weather conditions. Besides, hygiene related factors such as the public health measures by the government and possible personal awareness in the community can also affect the spread of infectious respiratory diseases. However, there is no quantitative support for this conclusion, because of lack of quality data. The severe acute respiratory syndrome (or SARS) outbreak in 2003 triggered strict public health measures and personal awareness in the prevention of infectious respiratory diseases, providing us an opportunity to quantify the impact of hygiene related factors in the spread of the disease. In this paper, we model the number of the respiratory illnesses by a semiparametric model which models the environmental and weather impacts using a multiple index model and the impact of other public health measures and possible personal awareness using a growth curve with jump. Using data from Hong Kong, we found that public health measures contributed to about 39% of reduction in the number of respiratory illnesses during the SARS period. However, the impact of hygienically related factors eventually fades as time passes. The results provide indirect quantitative support to the usefulness of governmental campaigns to arouse the awareness of the public in staying away from transmission of respiratory diseases during the full outbreak of the disease. The results also show the fast fading of alertness of Hong Kong people towards the epidemic. Furthermore, our model also offers a way to model the impacts of environmental factors on respiratory diseases, when the data contains the effect of human intervention, by introducing the change point and growth curve to remove such an effect.

[1]  Heung Wong,et al.  Effect of ambient air pollution on respiratory illness in Hong Kong: a regional study , 2009 .

[2]  M. Kenward,et al.  An Introduction to the Bootstrap , 2007 .

[3]  S. Leeder,et al.  Acute effects of urban ambient air pollution on respiratory symptoms, asthma medication use, and doctor visits for asthma in a cohort of Australian children. , 2004, Environmental research.

[4]  Boštjan Gomišček,et al.  Acute effects of particulate matter on respiratory diseases, symptoms and functions:: epidemiological results of the Austrian Project on Health Effects of Particulate Matter (AUPHEP) , 2004 .

[5]  Ker-Chau Li,et al.  Sliced Inverse Regression for Dimension Reduction , 1991 .

[6]  J. Schwartz,et al.  Short term effects of air pollution on health: a European approach using epidemiologic time series data: the APHEA protocol. , 1996, Journal of epidemiology and community health.

[7]  John J. McArdle,et al.  Growth Curve Analysis in Contemporary Psychological Research , 2003 .

[8]  Peter J Green,et al.  Lead discussion on 'Varying coefficient models' by Hastie & Tibshirani , 1993 .

[9]  Ruey S. Tsay,et al.  Functional-Coefficient Autoregressive Models , 1993 .

[10]  Thomas M. Stoker,et al.  Investigating Smooth Multiple Regression by the Method of Average Derivatives , 2015 .

[11]  A. Danchin,et al.  The Severe Acute Respiratory Syndrome , 2003 .

[12]  Susan Solomon,et al.  Observations of a “weekend effect” in diurnal temperature range , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[13]  F. Dominici,et al.  Airborne particulate matter and mortality: timescale effects in four US cities. , 2003, American journal of epidemiology.

[14]  Robert Maynard,et al.  Key airborne pollutants--the impact on health. , 2004, The Science of the total environment.

[15]  F. Dominici,et al.  Combining evidence on air pollution and daily mortality from the 20 largest US cities: a hierarchical modelling strategy , 2000 .

[16]  F. J. Richards.  A Flexible Growth Function for Empirical Use , 1959 .

[17]  Ker-Chau Li.  Sliced inverse regression for dimension reduction (with discussion) , 1991 .

[18]  L. Ho,et al.  The impact of community psychological responses on outbreak control for severe acute respiratory syndrome in Hong Kong , 2003, Journal of epidemiology and community health.

[19]  H. Tong,et al.  Article: 2 , 2002, European Financial Services Law.

[20]  J. Schwartz,et al.  Harvesting and long term exposure effects in the relation between air pollution and mortality. , 2000, American journal of epidemiology.

[21]  J. Scott Greene,et al.  The impacts of weather and pollution on human mortality in Birmingham, Alabama and Philadelphia, Pennsylvania , 2000 .

[22]  S. Navrud.  Valuing Health Impacts from Air Pollution in Europe , 2001 .

[23]  Tord Kjellstrom,et al.  Spatial analysis of annual air pollution exposure and mortality. , 2003, The Science of the total environment.

[24]  Scott L. Zeger,et al.  Harvesting-resistant estimates of air pollution effects on mortality. , 1999 .

[25]  R. H. Moore,et al.  Regression Graphics: Ideas for Studying Regressions Through Graphics , 1998, Technometrics.

[26]  Duncan Lee,et al.  Air pollution and health in Scotland: a multicity study. , 2009, Biostatistics.

[27]  Kristin Aunan,et al.  Exposure-response functions for health effects of ambient air pollution applicable for China -- a meta-analysis. , 2004, The Science of the total environment.

[28]  Yingcun Xia,et al.  Cumulative effects of air pollution on public health , 2006, Statistics in medicine.

[29]  S L Zeger,et al.  Harvesting-resistant estimates of air pollution effects on mortality. , 1999, Epidemiology.

[30]  Quanxi Shao,et al.  A REPARAMETERISATION METHOD FOR EMBEDDED MODELS , 2002 .