HbA 1c and cardiovascular risk score identify people who may benefit from preventive interventions: a 7 year follow-up of a high-risk screening programme for diabetes in primary care (ADDITION), Denmark

Aims/hypothesis The measurement of HbA 1c is suggested as a diagnostic test for diabetes. Screening for diabetes also identifies individuals with elevated cardiovascular risk but who are free of diabetes. This study aims to assess whether screening by HbA 1c or glucose measures alone, or in combination with a cardiovascular risk assessment, identifies people who may benefit from preventive interventions, i.e. people with screen detected diabetes and people belonging to groups with excess mortality, during a median follow-up of 7 years. Methods A population-based, stepwise high-risk screening programme was performed in 193 family practices from 2001 to 2006. Individuals aged between 40 and 69 years ( N = 163,185) were sent a diabetes risk questionnaire. Of these, 20,916 people at risk of diabetes were stratified by glucose measures (normal glucose tolerance [NGT], impaired fasting glucose [IFG], impaired glucose tolerance [IGT] and diabetes), HbA 1c (<6%; 6.0–6.4%; or ≥6.5%) and cardiovascular risk (heart SCORE <5 or ≥5). People were followed for a median of 7 years or until death. Excess mortality was calculated using the Cox hazard ratio (HR). Results SCORE ≥ 5 identified 91.7% (95% CI 91.1–92.3%) of those who might benefit from preventive interventions. SCORE ≥ 5 in combination with HbA 1c ≥ 6.0% identified 96.7% (95% CI 96.3–97.0%), compared with 97.6% (95%CI 97.2–97.9%) in combination with glucose measures. Glucose measures or HbA 1c alone identified 26.1% (95% CI 25.2–27.0%) and 19.8% (95% CI 19.0–20.6%), respectively. Conclusion/interpretation In a population-based high risk screening programme in primary care, HbA 1c ≥ 6.0% combined with an elevated cardiovascular risk assessment (SCORE ≥ 5) can feasibly be used to identify those who may benefit from preventive lifestyle intervention and/or polypharmacy. Trial registration ClinicalTrials.gov NCT 00237549. Funding The study received unrestricted grants from Novo Nordisk, Novo Nordisk Scandinavia, Astra Denmark, Pfizer Denmark, GlaxoSmithKline Pharma Denmark, Servier Denmark and HemoCue Denmark.