Understanding the impact of the follow-up period on the association between excess body weight, and cardiovascular events and mortality: a prospective cohort study of the UK Biobank.

objectiveStudies have examined the association between excess body weight and risk of cardiovascular (CV) outcomes in the general population. However, the impact of the follow-up period of excess body weight on the association between excess weight and CV outcomes is less investigated. We sought to investigate this using the UK Biobank data. STUDY

designPopulation-based prospective cohort study.

settingThe UK.

participantsAdults aged between 40 and 69 years were recruited between 2006 and 2010. The study included 469 162 participants; the median (IQR) age was 57 (50-63) years, and 56.3% of the participants were female. EXPOSURES: Body mass index, age, gender, ethnicity, education, smoking status (never, previous and current), alcohol status (never, previous and current), systolic blood pressure, sleep duration, walking pace, overall health rating (excellent, good, fair and poor), dietary patterns (such as red and processed meat consumption, and intake of fish, fruit, poultry and vegetables) and self-reported medical history (such as diabetes, chest pain/discomfort and falls). OUTCOMES: CV outcomes, including CV events such as cerebrovascular disease, ischaemic heart disease, heart failure and CV death.

resultsOf the 469 162 participants without CV disease at baseline, 56.3% were female. The mean age was 57 (SD: 9.6) years. During the median follow-up of 13.7 (IQR: 12.9-14.4) years, 27 305 participants developed a CV outcome, including 6698 who had a CV death. Overall, the strength of association between obesity and CV outcomes increased gradually as the follow-up period increased compared with normal weight. A significant association between obesity and the first CV event was observed after 4 years follow-up period (HR (95% CI) 1.14 (1.02 to 1.26)). The association of obesity with CV death was found after 10 years of follow-up, and there was an increasing strength of the association between 10 years (1.11 (1.01 to 1.22)) and 15 years (1.21 (1.13 to 1.29)) follow-up periods. No association was found between being overweight and CV death at any follow-up. Both overweight and obesity in men were associated with CV death observed before 8 years, while obese women were found to be associated with CV events and CV death after 8 years follow-up period.

conclusionsThis large observation study shows that obesity could lead to CV death as early as 10 years follow-up period, while individuals who were obese were more likely to have their first CV event after 4 years follow-up. No association between being overweight and CV death was observed in any follow-up time. Further studies are needed to evaluate the impact of the follow-up period on associations between overweight/obesity and CV outcomes. Screening or early intervention for obesity can be highly valuable for preventing and managing CV outcomes in a primary care setting.