Cross-sectional comparison of point-of-care with laboratory HbA(1c) in detecting diabetes in real-world remote Aboriginal settings

OBJECTIVES: To determine if point-of-care (POC) glycated haemoglobin (HbA(1c)) is sufficiently accurate in real-world remote settings to predict or exclude the diagnosis of diabetes based on laboratory HbA(1c) measurements. DESIGN: Cross-sectional study comparing POC capillary HbA(1c) results with corresponding venous HbA(1c) 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 HbA(1c) measurement and laboratory measurement of venous blood HbA(1c) level; POC capillary blood HbA(1c) 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 HbA(1c) 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 HbA(1c) 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.