Assessing the severity of cardiovascular disease in 213,088 people with coronary heart disease (CHD) in England: a retrospective cohort study using the Clinical Practice Research Datalink.
Problem
Coronary heart disease (CHD) is the most common cardiovascular (CV) disease (CVD) and was responsible for nearly 9.5m deaths worldwide in 2016. In the UK, nearly 2.3m people have CHD. Despite the importance of assessing CV severity, however, no established CVD severity scores for primary care patients with CHD exist. Past studies examining CVD severity in patients with CHD are limited, with most currently available CV risk stratification tools are for people without prevalent CVD.Our study aims: 1) develop and validate CV severity score in people with CHD using routinely-collected clinical data; 2) evaluate its association with risks of all-cause and cause-specific hospitalisation and mortality.
Approach
A retrospective cohort study using Clinical Practice Research Data link (CPRD) GOLD data between 2007-2017. People with CHD aged ≥35years and registered in English general practices were included. The study population was randomly divided into 80% and 20% parts as the training and validation datasets, respectively. Baseline and longitudinal severity scores were developed based on 20 relevant severity domains. Cox regression models and competing risk regressions were used to evaluate the association between severity and 1-year all-cause mortality (primary outcome), 1-year hospitalisations (secondary outcomes) after controlling for age, gender, ethnicity, and deprivation.Patient and public involvement and Engagement (PPIE): we invited people with CHD to a PPIE meeting to obtain their opinions on the included severity domains and the readability of our lay summary. All participants agreed on the importance of grading disease severity and their perceptions about the domains varied.
Findings
A cohort of 213,088 people with CHD (170,395 in the training dataset and 42,693 in the validation dataset) from 398 general practices was identified. Mean (±SD) age was 64.5 (±12.7) years, 98,041 (46%) were women, 189,272 (89%) White, and 45,719 (22%) and 34,412 (16%) from least and most deprived areas, respectively.Overall, 49,918 (23%) patients died, and 173,204 (81%) patients had ≥1 hospitalisation during 9.4 (±6.0) years of follow-up. A 1-unit increase in baseline severity score was associated with significantly 41% increased risk for all-cause mortality (95%CI: 37%-45%, AUROC=0.83). In the competing risk regressions, a 1-unit increase in score was associated with 28% increased risk for any-cause hospitalisation (27%-29%, AIC=992,096), and 39% risk for CV/diabetes hospitalisation (37%-40%, AIC=699,635). The new score improved the models' predictive value for all outcomes when added to socio-demographic variables. The findings were consistent in the validation dataset.Conclusions: A higher CV severity score in people with CHD is associated with increased risks for any cause and CV-related hospital admissions and mortality.
Consequences
This reproducible scoring tool based on routinely-collected data can support practitioners to provide better clinical management of CHD in primary care with wider implications on public health programmes for people with CHD and informing commissioning.