Evidence from big data in obesity research: international case studies.

BACKGROUND/OBJECTIVE: Obesity is thought to be the product of over 100 different factors, interacting as a complex system over multiple levels. Understanding the drivers of obesity requires considerable data, which are challenging, costly and time-consuming to collect through traditional means. Use of 'big data' presents a potential solution to this challenge. Big data is defined by Delphi consensus as: always digital, has a large sample size, and a large volume or variety or velocity of variables that require additional computing power (Vogel et al. Int J Obes. 2019). 'Additional computing power' introduces the concept of big data analytics. The aim of this paper is to showcase international research case studies presented during a seminar series held by the Economic and Social Research Council (ESRC) Strategic Network for Obesity in the UK. These are intended to provide an in-depth view of how big data can be used in obesity research, and the specific benefits, limitations and challenges encountered. METHODS AND RESULTS: Three case studies are presented. The first investigated the influence of the built environment on physical activity. It used spatial data on green spaces and exercise facilities alongside individual-level data on physical activity and swipe card entry to leisure centres, collected as part of a local authority exercise class initiative. The second used a variety of linked electronic health datasets to investigate associations between obesity surgery and the risk of developing cancer. The third used data on tax parcel values alongside data from the Seattle Obesity Study to investigate sociodemographic determinants of obesity in Seattle. CONCLUSIONS: The case studies demonstrated how big data could be used to augment traditional data to capture a broader range of variables in the obesity system. They also showed that big data can present improvements over traditional data in relation to size, coverage, temporality, and objectivity of measures. However, the case studies also encountered challenges or limitations; particularly in relation to hidden/unforeseen biases and lack of contextual information. Overall, despite challenges, big data presents a relatively untapped resource that shows promise in helping to understand drivers of obesity.

Obesity surgery and risk of colorectal and other obesity-related cancers: An English population-based cohort study.

BACKGROUND: The association between obesity surgery (OS) and cancer risk remains unclear. We investigated this association across the English National Health Service. A population-based Swedish study has previously suggested that OS may increase the risk of developing colorectal cancer (CRC). METHODS: A retrospective observational study of individuals who underwent OS (surgery cohort) or diagnosed with obesity, but had no OS (no-surgery cohort) (1997-2013) were identified using Hospital Episode Statistics. Subsequent diagnosis of CRC, breast, endometrial, kidney and lung cancer, as well as time 'at risk', were determined by linkage to National Cancer Registration & Analysis Service and Office of National Statistics data, respectively. Standardised incidence ratios (SIR) in relation to OS were calculated. RESULTS: 1 002 607 obese patients were identified, of whom 3.9% (n = 39 747) underwent OS. In the no-surgery obese population, 3 237 developed CRC (SIR 1.12 [95% CI 1.08-1.16]). In those who underwent OS, 43 developed CRC (SIR 1.26 [95% CI 0.92-1.71]). The OS cohort demonstrated decreased breast cancer risk (SIR 0.76 [95% CI 0.62-0.92]), unlike the no surgery cohort (SIR 1.08 [95% CI 1.04-1.11]). Increased risk of endometrial and kidney cancer was observed in surgery and no-surgery cohorts. CONCLUSIONS: CRC risk is increased in individuals diagnosed as obese. Prior obesity surgery was not associated with an increased CRC risk. However, the OS population was small, with limited follow-up. Risk of breast cancer after OS is reduced compared with the obese no-surgery population, while the risk of endometrial and kidney cancers remained elevated after OS.

A retrospective observational study of length of stay in hospital after colorectal cancer surgery in England (1998-2010).

The National Health Service (NHS) is facing financial constraints and thus there is considerable interest in ensuring the shortest but optimal hospital stays possible. The aim of this study was to investigate patterns of postoperative length of stay (LOS) stay across the English NHS and to identify factors that significantly influence both optimal and prolonged LOS.Data were obtained from the National Cancer Data Repository (NCDR). National patterns of LOS were examined and multilevel mixed effects logistic regression was used to study factors associated with an "ideal" (≤5 days) or a prolonged (≥21 days) LOS in hospital after major resection. Funnel plots were used to examine variation across hospitals in both risk-adjusted and unadjusted LOS.All 240,873 individuals who underwent major resection for colorectal cancer were diagnosed between 1998 and 2010 in the English NHS. The overall median LOS was 10 (interquartile range [IQR] 7-14 days) days, but it fell over time from 11 (IQR 9-15) days in 1998 to 7 (IQR 5-12) days in 2010. The proportion of people experiencing "ideal" LOS increased dramatically from 4.9% in 1998 to 34.2% in 2010, but the decrease in the proportion of patients who experienced a prolonged LOS was less marked falling from 11.2% to 8.4%, respectively. Control charts showed that there was significant variation in short and prolonged LOS across NHS trusts even after adjustment for case-mix.Significant variation in LOS existed between NHS hospitals in England throughout period 1998 to 2010. Understanding the underlying causes of this variation between surgical providers will make it possible to identify and spread best practice, improve services, and ultimately reduce LOS following colorectal cancer surgery.

Incidence of oral cancer among South Asians and those of other ethnic groups by sex in West Yorkshire and England, 2001-2006.

In 2008 there were 11682 cases of oral cancer in the United Kingdom; this is 16.41/100000 population, and 3.7% of all cancers. Ethnic coding of these data is poor, and so databases were combined to report rates for the incidence of oral cancer in South Asians compared with those among other ethnic groups in West Yorkshire, 2001-2006. A total of 2157 patients with oral cancer were identified in West Yorkshire, 138 of whom were South Asian (6.4%). We analysed them by ethnicity, sex, area in which they lived, and site of cancer. Oral cancer was significantly more common among South Asian women than those from other ethnic groups in England and West Yorkshire, and in England alone it was significantly more common in men of other ethnic groups than those from South Asia. Patients from South Asia were at higher risk of being diagnosed with oral cancer than those of other ethnic groups within West Yorkshire, when data were adjusted for age at diagnosis and sex. In England and in West Yorkshire there was a significantly higher rate of oral cancer among Southern Asian women than among those of other ethnic groups, and men in other ethnic groups had a higher incidence than those from South Asia (England only). The excess of oral cancers gives further weight to the association between smokeless tobacco, smoking, alcohol, and dietary intake by ethnic group. This information is particularly pertinent in areas such as West Yorkshire where there are large groups of Asian people.