Imperial College London

Dr Kiara C-M Chang

Faculty of MedicineSchool of Public Health

NIHR Research Fellow







Reynolds BuildingCharing Cross Campus





Publication Type

13 results found

Chang C-M, Mayne E, Laverty A, Agaku I, Filippidis Fet al., 2021, Cigarette prices in eight sub-Saharan African countries in 2018: a cross-sectional analysis, BMJ Open, Vol: 11, ISSN: 2044-6055

Objective: While the trend in smoking prevalence is decreasing worldwide, the number of male tobacco smokers is growing in Africa. This study compares the cigarette market in eight sub-Saharan African countries. This includes examining cigarette prices, pricing differentials, pack sizes and affordability at national and subnational levels.Design and setting: A cross-sectional data analysis using data from the Data on Alcohol and Tobacco in Africa (DATA) Project. The DATA Project was centrally coordinated by project supervisors following a standardised protocol. University students were recruited to conduct data collection and a total of 22 347 retail cigarette price data points collected between June and August 2018 were analysed (including Botswana, Ethiopia, Lesotho, Namibia, Nigeria, South Africa, Zambia and Zimbabwe). Prices were converted to US$ and standardised to the price of a 20-cigarette pack.Results: This research found large price differentials within provinces/states, with the gap between medium and minimum prices per 20-cigarette pack exceeding 50% of the medium price in 18 out of 24 provinces/states. Single cigarettes were widely available, especially in Lesotho and Ethiopia. Results of multivariable regression suggest prices (per 20-cigarette pack) were lower for cigarettes sold in packs than single sticks (−US$0.27, 95% CI: −US$0.39 to −US$0.23) and lower in less populated areas (−US$0.28 in rural compared with urban settings, 95% CI: −US$0.41 to −US$0.15). Availability of cheaper single cigarettes (lower per unit price than packed cigarettes) were identified for Lesotho and South Africa.Conclusions: These findings identify a varied picture in cigarette pricing in studied countries and suggest measures to tackle pricing differentials and availability of single sticks are warranted. These measures should counteract the potential health consequences of the increasing penetration of tobacco indus

Journal article

Chang K, Khandpur N, Neri D, Touvier M, Huybrechts I, Millett C, Vamos Eet al., 2021, Association between childhood consumption of ultraprocessed food and adiposity trajectories in the Avon Longitudinal Study of Parents and Children birth cohort, JAMA Pediatrics, Vol: 175, ISSN: 2168-6211

Importance Reports of associations between higher consumption of ultraprocessed foods (UPF) and elevated risks of obesity, noncommunicable diseases, and mortality in adults are increasing. However, associations of UPF consumption with long-term adiposity trajectories have never been investigated in children.Objective To assess longitudinal associations between UPF consumption and adiposity trajectories from childhood to early adulthood.Design, Setting, and Participants This prospective birth cohort study included children who participated in the Avon Longitudinal Study of Parents and Children (ALSPAC) in Avon County, southwest England. Children were followed up from 7 to 24 years of age during the study period from September 1, 1998, to October 31, 2017. Data were analyzed from March 1, 2020, to January 31, 2021.Exposures Baseline dietary intake data were collected using 3-day food diaries. Consumption of UPF (applying the NOVA food classification system) was computed as a percentage of weight contribution in the total daily food intake for each participant and categorized into quintiles.Main Outcomes and Measures Repeated recordings of objectively assessed anthropometrics (body mass index [BMI; calculated as weight in kilograms divided by height in meters squared], weight, and waist circumference) and dual-energy x-ray absorptiometry measurements (fat and lean mass indexes [calculated as fat and lean mass, respectively, divided by height in meters squared] and body fat percentage). Associations were evaluated using linear growth curve models and were adjusted for study covariates.Results A total of 9025 children (4481 [49.7%] female and 4544 [50.3%] male) were followed up for a median of 10.2 (interquartile range, 5.2-16.4) years. The mean (SD) UPF consumption at baseline was 23.2% (5.0%) in quintile 1, 34.7% (2.5%) in quintile 2, 43.4% (2.5%) in quintile 3, 52.7% (2.8%) in quintile 4, and 67.8% (8.1%) in quintile 5. Among those in the highest quintile of UPF

Journal article

Levy RB, Rauber F, Chang K, Louzada MLDC, Monteiro CA, Millett C, Vamos EPet al., 2021, Ultra-processed food consumption and type 2 diabetes incidence: A prospective cohort study., Clinical Nutrition, Vol: 40, Pages: 3608-3614, ISSN: 0261-5614

BACKGROUND: Ultra-processed foods account for more than 50% of daily calories consumed in several high-income countries, with sales of ultra-processed foods soaring globally, especially in middle-income countries. The objective of this study is to investigate the association between ultra-processed food (UPF) consumption and risk of type 2 diabetes (T2D) in a UK-based prospective cohort study. METHODS: Participants of the UK Biobank (2007-2019) aged 40-69 years without diabetes at recruitment who provided 24-h dietary recall and follow-up data were included. UPFs were defined using the NOVA food classification. Multivariable Cox proportional hazards regression models were used to evaluate the association between UPF consumption and the risk of T2D adjusting for socio-demographic, anthropometric and lifestyle characteristics. RESULTS: A total of 21,730 participants with a mean age of 55.8 years and mean UPF intake of 22.1% at baseline were included. During a mean follow-up of 5.4 years (116,956 person-years), 305 incident T2D cases were identified. In the fully adjusted model, compared with the group in the lowest quartile of UPF intake, the hazard ratio for T2D was 1.44, 1.04-2.02 in the group with the highest quartile of UPF consumption. A gradient of elevated risk of T2D associated with increasing quartiles of UPF intake was consistently observed (p value for trend < 0.028). A significantly increased risk of T2D was observed per 10 percentage points increment in UPF consumption ([adjusted HR]: 1.12, 95% confidence interval [CI]: 1.04-1.20). CONCLUSIONS: Our findings demonstrate that a diet high in UPFs is associated with a clinically important increased risk of T2D. Identifying and implementing effective public health actions to reduce UPF consumption in the UK and globally are urgently required.

Journal article

Filippidis F, Chang C-M, Blackmore I, Laverty Aet al., 2020, Prices and illicit trade of cigarettes in the European Union, a cross-sectional analysis, Nicotine and Tobacco Research, Vol: 22, Pages: 2271-2275, ISSN: 1462-2203

IntroductionWithin the context of the World Health Organization Framework Convention on Tobacco Control Protocol to Eliminate Illicit Trade in Tobacco Products and the impending revision of the EU directive on tobacco excise rules we assessed whether cigarettes price is linked to being offered illicit cigarettes.MethodsWe combined data being offered illicit cigarettes from the 2015 Special Eurobarometer Survey on Illicit Tobacco (N=27,672) with area-level data on Gross Domestic Product, unemployment, perceived corruption and sharing a border with a non-European Economic Area (non-EEA) state. We used the 2015 Weighted Average Price of cigarettes (WAP), which reflects the average price of a cigarette pack in each member state. We assessed associations between prices and illicit trade using 3-level ordered regression models.Results19.6% of respondents reported ever being offered illicit cigarettes, 6.4% repeatedly. In fully adjusted models WAP was not associated with being more likely to have been offered illicit market cigarettes more often (adjusted Odds Ratio=1.02, 95% Confidence Interval 0.91; 1.15). Sharing a border with a non-EEA member state was associated with increased likelihood of reporting being offered illicit cigarettes more often (1.73, 1.26;2.39).ConclusionThis study found no significant association between cigarette prices and reporting being offered illicit cigarettes; sharing a border with a non-EEA member state was linked to illicit trade. This study adds to evidence that increasing prices of cigarettes are not associated with illicit trade and that the focus should remain on securing supply chains, including through features such independent traceability systems.ImplicationsAfter adjusting for individual and regional factors, we did not identify an association between prices of cigarettes and likelihood of reporting being offered illicit cigarettes in the EU. Sharing a border with a non-EEA state however, was associated with increased likelihood of

Journal article

Rauber F, Chang K, Vamos EP, da Costa Louzada ML, Monteiro CA, Millett C, Levy RBet al., 2020, Ultra-processed food consumption and risk of obesity: a prospective cohort study of UK Biobank, EUROPEAN JOURNAL OF NUTRITION, Vol: 60, Pages: 2169-2180, ISSN: 1436-6207

Journal article

Parnham J, Millett C, Chang K, von Hinke S, Pearson-Stuttard J, Vamos EPet al., 2020, The Healthy Start scheme and its association with food expenditure in low-income families in the UK, Publisher: OXFORD UNIV PRESS, ISSN: 1101-1262

Conference paper

Palladino R, Vamos E, Chang K, Khunti K, Majeed A, Millett Cet al., 2020, Evaluation of the diabetes screening component of a national cardiovascular risk assessment programme in England: a retrospective cohort study, Scientific Reports, Vol: 10, ISSN: 2045-2322

Type 2 Diabetes (T2D) is increasing but the effectiveness of large-scale diabetes screening programmes is debated. We assessed associations between coverage of a national cardiovascular and diabetes risk assessment programme in England (NHS Health Check) and detection and management of incident cases of non-diabetic hyperglycaemia (NDH) and T2D. Retrospective analysis employing propensity score covariate adjustment method of prospectively collected data of 348,987 individuals aged 40–74 years and registered with 455 general practices in England (January 2009-May 2016). We examined differences in diagnosis of NDH and T2D, and changes in blood glucose levels and cardiovascular risk score between individuals registered with general practices with different levels (tertiles) of programme coverage. Over the study period 7,126 cases of NDH and 12,171 cases of T2D were detected. Compared with low coverage practices, incidence rate of detection in medium and high coverage practices were 15% and 19% higher for NDH and 10% and 9% higher for T2D, respectively. Individuals with NDH in high coverage practices had 0.2 mmol/L lower mean fasting plasma glucose and 0.9% lower cardiovascular risk score at follow-up. General practices actively participating in the programme had higher detection of NDH and T2D and improved management of blood glucose and cardiovascular risk factors.

Journal article

Nazar G, Chang KC-M, Srivastava S, Pearce N, Karan A, Millett Cet al., 2019, Impact of India’s National Tobacco Control Programme on bidi and cigarette consumption: a difference-in-differences analysis, Tobacco Control, Vol: 29, Pages: 103-110, ISSN: 0964-4563

Background Despite the importance of decreasing tobacco use to achieve mortality reduction targets of the Sustainable Development Goals in low-income and middle-income countries (LMICs), evaluations of tobacco control programmes in these settings are scarce. We assessed the impacts of India’s National Tobacco Control Programme (NTCP), as implemented in 42 districts during 2007–2009, on household-reported consumption of bidis and cigarettes.Methods Secondary analysis of cross-sectional data from nationally representative Household Consumer Expenditure Surveys (1999–2000; 2004–2005 and 2011–2012). Outcomes were: any bidi/cigarette consumption in the household and monthly consumption of bidi/cigarette sticks per person. A difference-in-differences two-part model was used to compare changes in bidi/cigarette consumption between NTCP intervention and control districts, adjusting for sociodemographic characteristics and time-based heterogeneity.Findings There was an overall decline in household-reported bidi and cigarette consumption between 1999–2000 and 2011–2012. However, compared with control districts, NTCP districts had no significantly different reductions in the proportions of households reporting bidi (adjusted OR (AOR): 1.03, 95% CI: 0.84 to 1.28) or cigarette (AOR: 1.01 to 95% CI: 0.82 to 1.26) consumption, or for the monthly per person consumption of bidi (adjusted coefficient: 0.07, 95% CI: −0.13 to 0.28) or cigarette (adjusted coefficient: −0.002, 95% CI: −0.26 to 0.26) sticks among bidi/cigarette consuming households.Interpretation Our findings indicate that early implementation of the NTCP may not have produced reductions in tobacco use reflecting generally poor performance against the Framework Convention for Tobacco Control objectives in India. This study highlights the importance of strengthening the implementation and enforcement of tobacco control policies in LMICs to ach

Journal article

Laverty AA, Vamos E, Millett C, Chang K, Filippidis F, Hopkinson Net al., 2019, Child awareness of and access to cigarettes – impacts of the point of sale display ban in England, Tobacco Control, Vol: 28, Pages: 526-531, ISSN: 0964-4563

Introduction England introduced a tobacco display ban for shops with >280 m2 floor area (‘partial ban’) in 2012, then a total ban in 2015. This study assessed whether these were linked to child awareness of and access to cigarettes.Methods Data come from the Smoking, Drinking and Drug Use survey, an annual survey of children aged 11–15 years for 2010–2014 and 2016. Multivariate logistic regression models assessed changes in having seen cigarettes on display, usual sources and ease of access to cigarettes in shopsResults During the partial display ban in 2012, 89.9% of children reported seeing cigarettes on display in the last year, which was reduced to 86.0% in 2016 after the total ban (adjusted OR 0.58, 95% CI 0.50 to 0.66). Reductions were similar in small shops (84.1% to 79.3%)%) and supermarkets (62.6% to 57.3%)%). Although the ban was associated with a reduction in the proportion of regular child smokers reporting that they bought cigarettes in shops (57.0% in 2010 to 39.8% in 2016), we did not find evidence of changes in perceived difficulty or being refused sale among those who still did.Discussion Tobacco point-of-sale display bans in England reduced the exposure of children to cigarettes in shops and coincided with a decrease in buying cigarettes in shops. However, children do not report increased difficulty in obtaining cigarettes from shops, highlighting the need for additional measures to tackle tobacco advertising, stronger enforcement of existing laws and measures such as licencing for tobacco retailers.

Journal article

Chang C, Vamos E, Palladino R, Majeed A, Lee T, Millett Cet al., 2018, Impact of the NHS Health Check on inequalities in cardiovascular disease risk: a difference-in-differences matching analysis, Journal of Epidemiology and Community Health, Vol: 73, Pages: 11-18, ISSN: 0143-005X

Background We assessed impacts of a large, nationwide cardiovascular disease (CVD) risk assessment and management programme on sociodemographic group inequalities in (1) early identification of hypertension, type 2 diabetes (T2D) and chronic kidney disease (CKD); and (2) management of global CVD risk among high-risk individuals.Methods We obtained retrospective electronic medical records from the Clinical Practice Research Datalink for a randomly selected sample of 138 788 patients aged 40–74 years without known CVD or diabetes, who were registered with 462 practices between 2009 and 2013. We estimated programme impact using a difference-in-differences matching analysis that compared changes in outcome over time between attendees and non-attendees.Results National Health Service Health Check attendance was 21.4% (29 672/138 788). A significantly greater number of hypertension and T2D incident cases were identified in men than women (eg, an additional 4.02%, 95% CI 3.65% to 4.39%, and 2.08%, 1.81% to 2.35% cases of hypertension in men and women, respectively). A significantly greater number of T2D incident cases were identified among attendees living in the most deprived areas, but no differences were found for hypertension and CKD across socioeconomic groups. No major differences in CVD risk management were observed between sociodemographic subgroups (eg, programme impact on 10-year CVD risk score was −1.13%, −1.48% to −0.78% in male and −1.53%, −2.36% to −0.71% in female attendees).Conclusion During 2009–2013, the programme had low attendance and small overall impacts on early identification of disease and risk management. The age, sex and socioeconomic subgroups appeared to have derived similar level of benefits, leaving existing inequalities unchanged. These findings highlight the importance of population-wide interventions to address inequalities in CVD outcomes.

Journal article

Woringer M, cecil E, watt H, chang K, hamid F, khunti K, dubois E, evason J, Majeed A, soljak Met al., 2017, Evaluation of community provision of a preventive cardiovascular programme - the National Health Service Health Check in reaching the under-served groups by primary care in England: cross sectional observational study, BMC Health Services Research, Vol: 17, ISSN: 1472-6963

Background:Cardiovascular disease (CVD) is the leading cause of premature mortality and a major contributor of health inequalities in England. Compared to more affluent and white counterparts, deprived people and ethnic minorities tend to die younger due to preventable CVD associated with lifestyle. In addition, deprived, ethnic minorities and younger people are less likely to be served by CVD prevention services. This study assessed the effectiveness of community-based outreach providers in delivering England’s National Health Services (NHS) Health Check programme, a CVD preventive programme to under-served groups.Methods:Between January 2008 and October 2013, community outreach providers delivered a preventive CVD programme to 50,573 individuals, in their local communities, in a single consultation without prescheduled appointments. Community outreach providers operated on evenings and weekends as well as during regular business hours in venues accessible to the general public. After exclusion criteria, we analysed and compared socio-demographic data of 43,177 Health Check attendees with the general population across 38 local authorities (LAs). We assessed variation between local authorities in terms of age, sex, deprivation and ethnicity structures using two sample t-tests and within local authority variation in terms of ethnicity and deprivation using Chi squared tests and two sample t-tests respectively.Results:Using Index of Multiple Deprivation, the mean deprivation score of the population reached by community outreach providers was 6.01 higher (p < 0.05) than the general population. Screened populations in 29 of 38 LAs were significantly more deprived (p < 0.05). No statistically significant difference among ethnic minority groups was observed between LAs. Nonetheless some LAs – namely Leicester, Thurrock, Sutton, South Tyneside, Portsmouth and Gateshead were very successful in recruiting ethnic minority groups. The mean proportion of men s

Journal article

CHANG C, LEE T, VAMOS E, SOLJAK M, JOHNSTON D, KHUNTI K, MAJEED A, MILLETT Cet al., 2016, Impact of NHS Health Check on cardiovascular disease risk: difference-in-differences matching analysis, Canadian Medical Association Journal, ISSN: 1488-2329

Journal article

Chang K, Soljak MA, Lee T, Woringer, Johnston, Khunti K, Majeed, Millettet al., 2015, Coverage of a national cardiovascular risk assessment and management programme (NHS Health Check): Retrospective database study, Preventive Medicine, Vol: 78, ISSN: 1096-0260

Journal article

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