Relation of Body Mass Index to Outcomes in Acute Coronary Syndrome

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We assessed the association of BMI with all-cause and cardiovascular (CV) mortality in a contemporary acute coronary syndrome cohort. Patients from the Australian Cooperative National Registry of Acute Coronary Care, Guideline Adherence and Clinical Events and Global Registry of Acute Coronary Events between 2009 and 2019, were divided into BMI subgroups (underweight: <18.5, healthy: 18.5 to 24.9, overweight: 25 to 29.9, obese: 30 to 39.9, extremely obese: >40). Logistic regression was used to determine the association between BMI group and outcomes of all cause and CV death in hospital, and at 6 months. 8,503 patients were identified, mean age 64 ± 13, 72% male. The BMI breakdown was: underweight- 95, healthy- 2,140, overweight- 3,258, obese- 2,653, extremely obese- 357. Obese patients were younger (66 ± 12 vs 67 ± 13), with more hypertension, diabetes, and dyslipidemia vs healthy (all p < 0.05). Obese had lower hospital mortality than healthy: all-cause: 1% versus 4%, aOR (95% CI): 0.49(0.27, 0.87); CV: 1% versus 3%, 0.51(0.27, 0.96). At 6-month underweight had higher mortality than healthy: all-cause: 11% versus 4%, 2.69(1.26, 5.76); CV: 7% versus 1%, 3.54(1.19, 10.54); whereas obese had lower mortality: all-cause: 1% versus 4%, 0.48(0.29, 0.77); CV: 0.4% versus 1%, 0.42(0.19, 0.93). When BMI was plotted as a continuous variable against outcome a U-shaped relationship was demonstrated, with highest event rates in the most obese (>60). In conclusion, BMI is associated with mortality following an acute coronary syndrome. Obese patients had the best outcomes, suggesting persistence of the obesity paradox. However, there was a threshold effect, and favorable outcomes did not extend to the most obese.

Section snippets

Background

Body mass index (BMI) is a commonly used metric used to determine whether patients are in a "healthy" range; with the extremes of BMI (underweight and overweight patients) both considered to have poorer overall outcomes. Obesity is becoming increasingly prevalent1; In Australia, 67% of the adult population were overweight (35.6%) or obese (31.3%).2 Obesity is a cardiovascular risk factor which predicts coronary artery disease, heart failure, and premature death.3, 4, 5, 6 However, in those with

Methods

We performed a retrospective analysis of the Australian Cooperative National Registry of Acute Coronary Care, Guideline Adherence and Clinical Events (CONCORDANCE) and the Australian cohort of the Global Registry of Acute Coronary Events (GRACE Australia), both have been described previously.16,17 Both databases are multicentre, prospective, national, electronic cohort registries that aim to provide information on patients with ACS throughout Australia.16,17 The registries were conducted at 52

Results

8503 patients were identified, mean age 64 ± 15, the majority were male (72%). The number of patients in each category were: underweight- 95, healthy- 2,140, overweight- 3,258, obese- 2,653, and extremely obese- 375. Underweight patients were older (69.3 ±15 vs 66.9±13), more likely to be female (61% vs 32%) and had a higher prevalence of anemia, peripheral vascular disease, and previous cardiac failure than healthy patients (all p<0.05). Obese were younger (62.2 ±13 vs 66.9±13), with a higher

Discussion

There are conflicting data on the association between obesity and being underweight on outcomes in those with established ACS. This retrospective, multicentre, observational study, spanning a 20-year period, is the largest on this subject in a contemporary Australian population. Our study shows the persistence of the obesity paradox for in-hospital cardiovascular and all-cause mortality, and the presence of a U shaped relationship between outcomes and increasing BMI at 6 months, where patients

Authors contribution

Seshika Ratwatte writing – conceptualisation, methodology, writing original draft, review and editing, Karice Hyun – methodology, formal analysis, writing – review and editing, Mario D'Souza - methodology, formal analysis, Jennifer Barraclough – conceptualisation, writing – review and editing, Derek P. Chew writing – review and editing, Pratap Shetty writing – review and editing,Sanjay Patel writing – review and editing, David Amos writing – review and editing, and David Brieger –

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    The CONCORDANCE registry has been funded by grants to the Sydney Local Health District from Sanofi Aventis, Astra Zeneca, Eli Lilly, Boehringer Ingelheim, the Merck Sharp and Dohme/Schering Plough joint venture, and the National Heart Foundation of Australia. The sponsors played no role in the design, analysis, or preparation of this study.

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    This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation.

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