Lifestyle trajectories and ischaemic heart diseases: a prospective cohort study in UK Biobank

Aims To evaluate the associations of baseline and long-term trajectories of lifestyle with incident ischaemic heart diseases (IHDs). Methods and results 29 164 participants in the UK Biobank who had at least one follow-up assessment and were free of IHD at the last follow-up assessment were included. We constructed a weighted unhealthy lifestyle score though summing five lifestyle factors [smoking, physical activity, diet, body mass index, and sleep duration]. Lifestyle assessed at baseline (2006-09), the first follow-up assessment (2012-13), and the second follow-up assessment (since 2014) were used to derive the trajectories of each individual. The joint categories were created through cross-classifying the three baseline lifestyle categories (ideal, intermediate, and poor) by the three lifestyle trajectory categories (improve, maintain, and decline). During a median follow-up period of 4.2 years, 868 IHD events were recorded. The hazard ratio (HR) of incident IHD associated with per unit increase in unhealthy lifestyle trajectory was 1.08 [95% confidence interval (CI): 0.99-1.17]. Subgroup analyses indicated such association was stronger among individuals with hypertension (HR: 1.13, 95% CI: 1.03-1.24), diabetes (HR: 1.23, 95% CI: 0.96-1.58), or hyperlipidaemia (HR: 1.09, 95% CI: 0.97-1.22). Compared with participants consistently adhering to an ideal lifestyle (ideal-maintain), the HRs of incident IHD were 1.30 (1.07-1.58) for intermediate-maintain, 1.52 (1.23-1.88) for poor-maintain, 1.25 (0.93-1.68) for intermedia-improve, 1.48 (1.17-1.88) for poor-improve, 1.46 (1.08-1.99) for intermedia-decline, and 1.77 (1.21-2.59) for poor-decline. Conclusions A declined lifestyle trajectory increased the risk of incident IHD, irrespective of baseline lifestyle levels. Individuals with hypertension, diabetes, or hyperlipidaemia were more predisposed to the influence of lifestyle change. Lay Summary It is known that an unhealthy lifestyle at baseline was associated with an increased risk of cardiovascular diseases (CVDs), but the risk attributed to the lifestyle changes (or trajectories) over the long term has not been well quantified. Meanwhile, the effects of lifestyle, either in baseline level or trajectories, on different CVD subtypes such as ischaemic heart diseases (IHDs) and stroke varied. Thus, this study used the data from UK Biobank to construct a weighted unhealthy lifestyle score and to evaluate the prospective associations of baseline and long-term trajectories of the unhealthy lifestyle score with the risk of incident IHD. A total of 352 251 and 29 164 participants were included in the unhealthy lifestyle construction and lifestyle trajectory analysis, respectively. We found a poorer lifestyle at baseline was significantly associated with an increased risk of incident IHD in a linear dose-response fashion. Besides, a declined lifestyle trajectory was associated with an increased risk of incident IHD, irrespective of baseline lifestyle levels, and such an association was stronger among individuals with hypertension, diabetes, or hyperlipidaemia. Compared with the maintainers, risks of incident IHD attenuated when individuals improved their lifestyle and strengthened when declined their lifestyle.A declined lifestyle trajectory increased the risk of incident IHD, irrespective of baseline lifestyle levels. Such association was stronger among participants with hypertension, diabetes, or hyperlipidaemia.Compared with the maintainers of lifestyle, risks of incident IHD attenuated when individuals improved their lifestyle and strengthened when declined their lifestyle.