Cross-sectional comparison of point-of-care with laboratory HbA1c in detecting diabetes in real-world remote Aboriginal settings

OBJECTIVES To determine if point-of-care (POC) glycated haemoglobin (HbA₁c) is sufficiently accurate in real-world remote settings to predict or exclude the diagnosis of diabetes based on laboratory HbA1c measurements. DESIGN Cross-sectional study comparing POC capillary HbA₁c results with corresponding venous HbA₁c levels measured in a reference laboratory. PARTICIPANTS Aboriginal patients ≥15 years old who were due for diabetes screening at the participating clinics were invited to participate. Two hundred and fifty-five Aboriginal participants were enrolled and 241 were included in the analysis. SETTING 6 primary healthcare sites in the remote Kimberley region of Western Australia from September 2011 to November 2013. MAIN OUTCOME MEASURES Concordance and mean differences between POC capillary blood HbA₁c measurement and laboratory measurement of venous blood HbA₁c level; POC capillary blood HbA1c equivalence value for screening for diabetes or a high risk of developing diabetes; sensitivity, specificity and positive-predictive value for diagnosing and screening for diabetes; barriers to conducting POC testing. RESULTS Concordance between POC and laboratory results was good (ρ=0.88, p<0.001). The mean difference was -0.15% (95% limits of agreement, -0.67% to 0.36%). POC HbA₁c measurements ≥6.5%, 48 mmol/mol had a specificity of 98.2% and sensitivity of 73.7% for laboratory measurements ≥6.5%. The POC equivalence value for screening for diabetes or a high risk of developing diabetes was ≥5.7%, 39 mmol/mol (sensitivity, 91%; specificity, 76.7% for laboratory measurements ≥6.0%, 42 mmol/mol). Staff trained by other clinic staff 'on the job' performed as well as people with formal accredited training. Staff reported difficulty in maintaining formal accreditation. CONCLUSIONS POC HbA₁c testing is sufficiently accurate to be a useful component in screening for, and diagnosing, diabetes in remote communities. Limited local training is adequate to produce results comparable to laboratory results and accreditation processes need to reflect this.