A Coupled Spatial-Network Model: A Mathematical Framework for Applications in Epidemiology.

There is extensive evidence that network structure (e.g., air transport, rivers, or roads) may significantly enhance the spread of epidemics into the surrounding geographical area. A new compartmental modeling framework is proposed which couples well-mixed (ODE in time) population centers at the vertices, 1D travel routes on the graph's edges, and a 2D continuum containing the rest of the population to simulate how an infection spreads through a population. The edge equations are coupled to the vertex ODEs through junction conditions, while the domain equations are coupled to the edges through boundary conditions. A numerical method based on spatial finite differences for the edges and finite elements in the 2D domain is described to approximate the model, and numerical verification of the method is provided. The model is illustrated on two simple and one complex example geometries, and a parameter study example is performed. The observed solutions exhibit exponential decay after a certain time has passed, and the cumulative infected population over the vertices, edges, and domain tends to a constant in time but varying in space, i.e., a steady state solution.

Global burden of diseases, injuries, and risk factors for young people's health during 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013.

BACKGROUND: Young people's health has emerged as a neglected yet pressing issue in global development. Changing patterns of young people's health have the potential to undermine future population health as well as global economic development unless timely and effective strategies are put into place. We report the past, present, and anticipated burden of disease in young people aged 10-24 years from 1990 to 2013 using data on mortality, disability, injuries, and health risk factors. METHODS: The Global Burden of Disease Study 2013 (GBD 2013) includes annual assessments for 188 countries from 1990 to 2013, covering 306 diseases and injuries, 1233 sequelae, and 79 risk factors. We used the comparative risk assessment approach to assess how much of the burden of disease reported in a given year can be attributed to past exposure to a risk. We estimated attributable burden by comparing observed health outcomes with those that would have been observed if an alternative or counterfactual level of exposure had occurred in the past. We applied the same method to previous years to allow comparisons from 1990 to 2013. We cross-tabulated the quantiles of disability-adjusted life-years (DALYs) by quintiles of DALYs annual increase from 1990 to 2013 to show rates of DALYs increase by burden. We used the GBD 2013 hierarchy of causes that organises 306 diseases and injuries into four levels of classification. Level one distinguishes three broad categories: first, communicable, maternal, neonatal, and nutritional disorders; second, non-communicable diseases; and third, injuries. Level two has 21 mutually exclusive and collectively exhaustive categories, level three has 163 categories, and level four has 254 categories. FINDINGS: The leading causes of death in 2013 for young people aged 10-14 years were HIV/AIDS, road injuries, and drowning (25·2%), whereas transport injuries were the leading cause of death for ages 15-19 years (14·2%) and 20-24 years (15·6%). Maternal disorders were the highest cause of death for young women aged 20-24 years (17·1%) and the fourth highest for girls aged 15-19 years (11·5%) in 2013. Unsafe sex as a risk factor for DALYs increased from the 13th rank to the second for both sexes aged 15-19 years from 1990 to 2013. Alcohol misuse was the highest risk factor for DALYs (7·0% overall, 10·5% for males, and 2·7% for females) for young people aged 20-24 years, whereas drug use accounted for 2·7% (3·3% for males and 2·0% for females). The contribution of risk factors varied between and within countries. For example, for ages 20-24 years, drug use was highest in Qatar and accounted for 4·9% of DALYs, followed by 4·8% in the United Arab Emirates, whereas alcohol use was highest in Russia and accounted for 21·4%, followed by 21·0% in Belarus. Alcohol accounted for 9·0% (ranging from 4·2% in Hong Kong to 11·3% in Shandong) in China and 11·6% (ranging from 10·1% in Aguascalientes to 14·9% in Chihuahua) of DALYs in Mexico for young people aged 20-24 years. Alcohol and drug use in those aged 10-24 years had an annual rate of change of >1·0% from 1990 to 2013 and accounted for more than 3·1% of DALYs. INTERPRETATION: Our findings call for increased efforts to improve health and reduce the burden of disease and risks for diseases in later life in young people. Moreover, because of the large variations between countries in risks and burden, a global approach to improve health during this important period of life will fail unless the particularities of each country are taken into account. Finally, our results call for a strategy to overcome the financial and technical barriers to adequately capture young people's health risk factors and their determinants in health information systems. FUNDING: Bill & Melinda Gates Foundation.

Mental distress and functional health in the United States.

INTRODUCTION: Mental illness prevalence is increasing in USA. Understanding the relationship between functional status and mental health is crucial in optimizing psychiatric treatment. METHODS: We used 2000-2014 BRFSS data to examine the relationship between functional health and frequent mental distress in 51 states. RESULTS: East-South-Central US (14.88%) had the highest prevalence of frequent mental distress and West-North-Central (9.42%) the lowest. Tennessee (15.7%) had the highest prevalence of frequent mental distress and North Dakota (7.4%) the lowest. East-South-Central had the highest prevalence on all functional limitation items. West Virginia had the highest prevalence of functional limitation (29.1%), use of special equipment (14.0%), blindness (8.6%), walking difficulty (23.0%), and difficulty running errands (12%). Females were more likely to report frequent mental distress in all states and more likely to report functional limitations in 32 states. Those who were divorced, smoker, unemployed, and of African American/American Indian/Alaskan native/other race were more likely to have a functional limitation. The prevalence of frequent mental distress increased steadily from 2000 for males and females but showed a decline from 2013 to 2014. The rate of increase was higher between 2008 and 2013 compared to previous years. CONCLUSIONS: Our study showed a high prevalence of mental distress and poor functional health in the US with a large variation between states and socio-demographic groups. Moreover, our findings showed a strong association between poor mental health and functional limitations. Our findings call for integrating mental and physical health research and clinical care to reduce the burden of mental health in the US.

Prevalence of asthma in Saudi adults: findings from a national household survey, 2013.

BACKGROUND: There are not enough data on the epidemiology of asthma in the Kingdom of Saudi Arabia (KSA). We analyzed data from a national household survey conducted in KSA in 2013 to estimate prevalence, associated risk factors and control measurements of asthma. METHODS: The Saudi Health Interview Survey was a cross-sectional national multistage survey of 10,735 individuals aged 15 years or older. The survey included a detailed household questionnaire and a physical exam. We used self-reported clinical diagnosis of asthma to assess prevalence of asthma. RESULTS: The prevalence of asthma in KSA was 4.05 % (95 % confidence interval [CI]: 3.54-4.62 %). Asthma was less frequent in individuals with higher education but higher in former smokers and obese individuals. Around 76.7 % of asthma patients (95 % CI: 70.6-82.0 %) experienced an asthmatic attack, and 61.6 % (95 % CI: 54.4-68.4 %) visited a hospital/emergency room because of asthma during the past year. Asthma attack was less frequent in older patients (odds ratio [OR] = 0.78, 95 %CI: 0.59-0.96 for each decade of life). Current use of medication for asthma was highly associated with asthma attacks (OR = 9.14, 95 % CI: 3.29-25.38). Asthma attack was also more frequent in individuals who were exposed to secondhand smoking (OR = 2.17, 95 %CI: 1.05-4.45) and those who were obese (OR = 3.01, 95 %CI: 1.34-6.78). CONCLUSION: Saudi Arabia has a relatively low prevalence of diagnosed asthma; however, many of the patients with known asthma do not have it under good control. Our study calls for programs to inform patients about the importance and proper means of controlling their condition. Implementing and monitoring of clinical guidelines can also help to improve asthma control among patients as well as identify undiagnosed cases.

Use of dental clinics and oral hygiene practices in the Kingdom of Saudi Arabia, 2013.

OBJECTIVES: We conducted a large household survey in 2013 to determine the current status of oral health practices and use of oral health services in the Kingdom of Saudi Arabia (KSA). METHODS: The Saudi Health Information Survey is a national multistage survey of individuals ≥ 15 years of age. We used a backward elimination multivariate logistic regression model to measure the association between having been to a dental clinic during the last year, and sex, age, marital status, education, time since last routine medical examination, history of diagnosis with a cardiovascular chronic condition, brushing or flossing teeth and use of Miswak (a chewing stick). RESULTS: Between April and June 2013, 10,735 participants completed the survey (89.4% of the households contacted). An estimated 1.5 million (11.5%) and 6.3 million (48.6%) Saudi Arabian people, ≥ 15 years of age, had visited a dental clinic for a routine check-up and for a complaint during the last year, respectively. In total, 16.3%, 85.0% and 52% of Saudi Arabian people never brush their teeth, never floss their teeth or never use Miswak, respectively. The probability of visiting a dental clinic increased with education, among individuals who brushed or flossed their teeth and who used Miswak. CONCLUSIONS: Oral hygiene practices are not common among Saudi Arabian people, and use of health care for prevention of oral disease is limited. Hence, the need for oral health promotion is pressing. The KSA Ministry of Health should develop and implement programmes, through its primary health clinics, to increase the awareness of the importance of good oral health.

On Your Mark, Get Set, Go: Levels of Physical Activity in the Kingdom of Saudi Arabia, 2013.

BACKGROUND: With the lack of appropriate data, we conducted a large household survey in 2013 to determine current rates of physical activity in the Kingdom of Saudi Arabia (KSA). METHODS: The Saudi Health Interview Survey is a national multistage survey of individuals aged 15 years or older. We used a multivariate logistic regression model to measure association between sociodemographic and selected characteristics and meeting the recommended levels of moderate and vigorous weekly physical activity. RESULTS: Of a total of 12,000 households contacted, 10,735 (89.4%) participants completed Saudi Health Interview Survey. An estimated 4.5 million (34.5%) Saudis aged 15 years or older reported no weekly physical activity, while only 1.7 million (12.9%) meet the recommended levels of moderate physical activity (MPA). The likelihood of meeting MPA decreased with age, education, among women, those with a history of diagnosis of select chronic conditions, including diabetes. Similar results were found for the likelihood of meeting the recommended levels of vigorous weekly physical activity. CONCLUSIONS: We found very low levels of physical activity in KSA. Perhaps, KSA can challenge communities or employers to devise solutions and reward those with the best results. These solutions would be of great value to other Gulf countries, as well.

Health in times of uncertainty in the eastern Mediterranean region, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013.

BACKGROUND: The eastern Mediterranean region is comprised of 22 countries: Afghanistan, Bahrain, Djibouti, Egypt, Iran, Iraq, Jordan, Kuwait, Lebanon, Libya, Morocco, Oman, Pakistan, Palestine, Qatar, Saudi Arabia, Somalia, Sudan, Syria, Tunisia, the United Arab Emirates, and Yemen. Since our Global Burden of Disease Study 2010 (GBD 2010), the region has faced unrest as a result of revolutions, wars, and the so-called Arab uprisings. The objective of this study was to present the burden of diseases, injuries, and risk factors in the eastern Mediterranean region as of 2013. METHODS: GBD 2013 includes an annual assessment covering 188 countries from 1990 to 2013. The study covers 306 diseases and injuries, 1233 sequelae, and 79 risk factors. Our GBD 2013 analyses included the addition of new data through updated systematic reviews and through the contribution of unpublished data sources from collaborators, an updated version of modelling software, and several improvements in our methods. In this systematic analysis, we use data from GBD 2013 to analyse the burden of disease and injuries in the eastern Mediterranean region specifically. FINDINGS: The leading cause of death in the region in 2013 was ischaemic heart disease (90·3 deaths per 100 000 people), which increased by 17·2% since 1990. However, diarrhoeal diseases were the leading cause of death in Somalia (186·7 deaths per 100 000 people) in 2013, which decreased by 26·9% since 1990. The leading cause of disability-adjusted life-years (DALYs) was ischaemic heart disease for males and lower respiratory infection for females. High blood pressure was the leading risk factor for DALYs in 2013, with an increase of 83·3% since 1990. Risk factors for DALYs varied by country. In low-income countries, childhood wasting was the leading cause of DALYs in Afghanistan, Somalia, and Yemen, whereas unsafe sex was the leading cause in Djibouti. Non-communicable risk factors were the leading cause of DALYs in high-income and middle-income countries in the region. DALY risk factors varied by age, with child and maternal malnutrition affecting the younger age groups (aged 28 days to 4 years), whereas high bodyweight and systolic blood pressure affected older people (aged 60-80 years). The proportion of DALYs attributed to high body-mass index increased from 3·7% to 7·5% between 1990 and 2013. Burden of mental health problems and drug use increased. Most increases in DALYs, especially from non-communicable diseases, were due to population growth. The crises in Egypt, Yemen, Libya, and Syria have resulted in a reduction in life expectancy; life expectancy in Syria would have been 5 years higher than that recorded for females and 6 years higher for males had the crisis not occurred. INTERPRETATION: Our study shows that the eastern Mediterranean region is going through a crucial health phase. The Arab uprisings and the wars that followed, coupled with ageing and population growth, will have a major impact on the region's health and resources. The region has historically seen improvements in life expectancy and other health indicators, even under stress. However, the current situation will cause deteriorating health conditions for many countries and for many years and will have an impact on the region and the rest of the world. Based on our findings, we call for increased investment in health in the region in addition to reducing the conflicts. FUNDING: Bill & Melinda Gates Foundation.

Access and barriers to healthcare in the Kingdom of Saudi Arabia, 2013: findings from a national multistage survey.

OBJECTIVES: We analysed data from a large household survey to identify barriers to healthcare in the Kingdom of Saudi Arabia. METHODS: The Saudi Health Interview Survey (SHIS) is a national multistage survey of individuals aged 15 years or older. The survey combined a household questionnaire and a laboratory blood analysis. We used a backward elimination multivariate logistic regression model to measure association between (1) diagnosis, (2) treatment, and (3) control of hypertension or diabetes and sociodemographic factors, history of diagnosis with chronic conditions, and type of, and distance travelled to, the clinic last visited. RESULTS: Between April and June 2013, a total of 10,735 participants completed SHIS and were invited to the local health clinics. Among hypertensive individuals, women, older individuals, and those previously diagnosed with diabetes and hypercholesterolaemia were more likely to have been diagnosed with hypertension than their counterparts. Among participants diagnosed with hypertension, the likelihood of being treated increased with age and education. The likelihood of having uncontrolled blood pressure despite treatment increased with education and a history of diagnosis with hypercholesterolaemia. Type of clinic visited and distance travelled to last clinic visit were not associated with diagnosis or treatment of hypertension or control of blood pressure. Similar factors were associated with the likelihood of diagnosis and treatment among individuals with diabetes. Having uncontrolled glycated haemoglobin levels, despite treatment, was less common among those who visited governmental clinics other than those of the Ministry of Health, compared with those who visited Ministry clinics. CONCLUSIONS: Our findings highlight the importance of individual characteristics in healthcare-seeking practices rather than system-based potential barriers. Saudis seem to mostly seek healthcare when sick. Hence, the Saudi Ministry of Health needs to implement a comprehensive plan including health education and investigations, to understand the barriers and bottlenecks to healthcare-seeking behaviour.