Research Article: Multimorbidity and survival for patients with acute myocardial infarction in England and Wales: Latent class analysis of a nationwide population-based cohort

Date Published: March 6, 2018

Publisher: Public Library of Science

Author(s): Marlous Hall, Tatendashe B. Dondo, Andrew T. Yan, Mamas A. Mamas, Adam D. Timmis, John E. Deanfield, Tomas Jernberg, Harry Hemingway, Keith A. A. Fox, Chris P. Gale, Carolyn S. P. Lam

Abstract: BackgroundThere is limited knowledge of the scale and impact of multimorbidity for patients who have had an acute myocardial infarction (AMI). Therefore, this study aimed to determine the extent to which multimorbidity is associated with long-term survival following AMI.Methods and findingsThis national observational study included 693,388 patients (median age 70.7 years, 452,896 [65.5%] male) from the Myocardial Ischaemia National Audit Project (England and Wales) who were admitted with AMI between 1 January 2003 and 30 June 2013. There were 412,809 (59.5%) patients with multimorbidity at the time of admission with AMI, i.e., having at least 1 of the following long-term health conditions: diabetes, chronic obstructive pulmonary disease or asthma, heart failure, renal failure, cerebrovascular disease, peripheral vascular disease, or hypertension. Those with heart failure, renal failure, or cerebrovascular disease had the worst outcomes (39.5 [95% CI 39.0–40.0], 38.2 [27.7–26.8], and 26.6 [25.2–26.4] deaths per 100 person-years, respectively). Latent class analysis revealed 3 multimorbidity phenotype clusters: (1) a high multimorbidity class, with concomitant heart failure, peripheral vascular disease, and hypertension, (2) a medium multimorbidity class, with peripheral vascular disease and hypertension, and (3) a low multimorbidity class. Patients in class 1 were less likely to receive pharmacological therapies compared with class 2 and 3 patients (including aspirin, 83.8% versus 87.3% and 87.2%, respectively; β-blockers, 74.0% versus 80.9% and 81.4%; and statins, 80.6% versus 85.9% and 85.2%). Flexible parametric survival modelling indicated that patients in class 1 and class 2 had a 2.4-fold (95% CI 2.3–2.5) and 1.5-fold (95% CI 1.4–1.5) increased risk of death and a loss in life expectancy of 2.89 and 1.52 years, respectively, compared with those in class 3 over the 8.4-year follow-up period. The study was limited to all-cause mortality due to the lack of available cause-specific mortality data. However, we isolated the disease-specific association with mortality by providing the loss in life expectancy following AMI according to multimorbidity phenotype cluster compared with the general age-, sex-, and year-matched population.ConclusionsMultimorbidity among patients with AMI was common, and conferred an accumulative increased risk of death. Three multimorbidity phenotype clusters that were significantly associated with loss in life expectancy were identified and should be a concomitant treatment target to improve cardiovascular outcomes.Trial NCT03037255.

Partial Text: The increasing prevalence of long-term health conditions, and consequent growing prevalence of multimorbidity (the presence of multiple co-morbidities), is a major global challenge facing healthcare systems [1,2]. Presently, around two-thirds of patients with cardiovascular disease are estimated to have at least 1 long-term health condition [3]. With improved survival rates following acute myocardial infarction (AMI) as well as an ageing population [4–6], there are more patients living longer with multimorbidity, which is associated with reduced quality of life, increased healthcare burden, and increased mortality [3,7,8].

There were a total of 693,388 patients included (median age 70.7 years; 452,896 [65.5%] men) and 1,872,468 person-years follow-up. There were 412,809 (59.5%) patients with AMI who had at least 1 pre-existing co-morbid condition. The majority of these had 1 condition (238,302, 57.7%), whereas 120,693 (29.2%) had 2, and 53,814 (13.0%) had 3 or more, up to a maximum of 7 (63, 0.02%). The most prevalent conditions were hypertension (n = 302,388, 45.9%), diabetes mellitus (n = 122,228, 18.6%), and COPD or asthma (n = 89,211, 13.6%). Whilst chronic renal failure, chronic heart failure, and peripheral vascular disease were the least prevalent, patients with these conditions most frequently had additional conditions (27,812 [89.6%], 28,445 [84.1%], and 23,201 [84.0%], respectively) (Fig 1).

In this nationwide study of patients hospitalised with AMI, almost two-thirds had multimorbidity, most commonly with hypertension and diabetes mellitus. Those with 1 long-term health condition in addition to AMI were 32% more likely to die over the 8.4-year follow-up period, whereas those with 2 or more long-term health conditions were twice as likely to die, compared with those without multimorbidity. Each condition was associated with a unique and significant loss of life expectancy, which was greatest for those with chronic heart failure. Using latent class analysis, we identified 3 patient groups based on their probability of long-term health conditions that had distinct survival trajectories and may be considered as novel post-AMI survival phenotypes.



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