Validation and recalibration of the Framingham cardiovascular disease risk models in an Australian Indigenous cohort

Abstract

BackgroundIn Australia, clinical guidelines for primary prevention of cardiovascular disease recommend the use of the Framingham model to help identify those at high risk of developing the disease. However, this model has not been validated for the Indigenous population.DesignCohort study.MethodsFramingham models were applied to the Well Person’s Health Check (WPHC) cohort (followed 1998–2014), which included 1448 Aboriginal and Torres Strait Islanders from remote Indigenous communities in Far North Queensland. Cardiovascular disease risk predicted by the original and recalibrated Framingham models were compared with the observed risk in the WPHC cohort.ResultsThe observed five- and 10-year cardiovascular disease probability of the WPHC cohort was 10.0% (95% confidence interval (CI): 8.5–11.7) and 18.7% (95% CI: 16.7–21.0), respectively. The Framingham models significantly underestimated the cardiovascular disease risk for this cohort by around one-third, with a five-year cardiovascular disease risk estimate of 6.8% (95% CI: 6.4–7.2) and 10-year risk estimates of 12.0% (95% CI: 11.4–12.6) and 14.2% (95% CI: 13.5–14.8). The original Framingham models showed good discrimination ability (C-statistic of 0.67) but a significant lack of calibration (χ2 between 82.56 and 134.67). After recalibration the 2008 Framingham model corrected the underestimation and improved the calibration for five-year risk prediction (χ2 of 18.48).ConclusionsThe original Framingham models significantly underestimate the absolute cardiovascular disease risk for this Australian Indigenous population. The recalibrated 2008 Framingham model shows good performance on predicting five-year cardiovascular disease risk in this population and was used to calculate the first risk chart based on empirical validation using long-term follow-up data from a remote Australian Indigenous population.

Cardiovascular disease risk assessment for Aboriginal and Torres Strait Islander adults aged under 35 years: a consensus statement

“…While studies in remote communities have shown that, applied alone, FRE underestimates the risk of CVD events, these findings may not apply to all Aboriginal and Torres Strait Islander peoples. The findings from these communities are likely to reflect a clustering of non‐FRE risk factors, including socio‐economic disadvantage, rather than an inherent underestimation of CVD risk due to race.…”

“…Until these risk calculators are updated, when assessing absolute CVD risk in Aboriginal and Torres Strait Islander peoples aged 30–34 years, clinicians should enter an age of 35 years. Studies comparing predicted and observed numbers of CVD events in remote Aboriginal and Torres Strait Islander populations have shown that FRE underestimates the risk of CVD events in people aged less than 35 years . Therefore, the use of a slightly older age in these situations is unlikely to significantly inflate CVD risk.…”

Absolute cardiovascular disease risk and lipid‐lowering therapy among Aboriginal and Torres Strait Islander Australians

“…‐ 27 However, data on the exact probability of CVD events in people with each condition by age are limited, especially at younger ages and for Aboriginal and Torres Strait Islander people. Further validation and calibration of CVD risk assessment for Aboriginal and Torres Strait Islander people is needed to improve CVD prevention 28 …”

“…Further validation and calibration of CVD risk assessment for Aboriginal and Torres Strait Islander people is needed to improve CVD prevention. 28 Although estimates from the AATSIHS sample are considered to be nationally representative, the survey did not sample individuals from non-private dwellings (eg, hotels, short stay caravan parks, hospitals, prisons). However, our sample was the largest and most representative sample of an indigenous population, in Australia or elsewhere, ever assessed for CVD risk, and population weights were applied to achieve reliable estimates.…”

Development and Use of Prediction Models for Classification of Cardiovascular Risk of Remote Indigenous Australians

“…While the annual CVD risk assessment using a validated absolute risk algorithm has been recommended for Indigenous Australians [7], there is widespread belief that current tools have deficiencies in assessing CVD risk in this high risk population [6,8,9]. Several studies have shown that the equations derived from the Framingham study underestimate the CVD risk of Indigenous Australians [10,11]. One explanation for this underestimation may be that certain CVD risk factors for Indigenous people such as albuminuria and waist circumference are not included in the Framingham CVD equations [2,3,12,13].…”