Sunday, 18 November 2012

Six-monthly HbA1c tests in diabetes 'unnecessary'

GPs do not need to test blood glucose in patients with stable diabetes every six months, as recommended by NICE, as it leads to a high rate of false positives an NHS report has concluded.
Annual monitoring would give more meaningful information on changes to HbA1c which for most people happen quite slowly, the NHS Diabetes report said.
Statistical modelling showed for patients whose HbA1c is currently 56mmol/mol, six-monthly monitoring would pick up 405 positive tests per 1,000 patients – that is HbAlc readings above 58.5 mmol/mol - but 28% of those would be due to measurement variation and not a real increase.
For the same group of patients annual monitoring would pick up 479 per 1,000 patients but with only 16% would be false positives, the University of Oxford researchers who did the analysis found.
In other groups with lower starting HbA1c readings most of the positive tests seen with six-monthly tests would be false positives, the report said.
For someone with a starting HbA1c, a positive test six months later has a 64% chance of being false compared with 31% after a year, the figures showed.
‘For many people with diabetes, six-monthly monitoring is more likely to yield a false-positive test – attributable to the within-measurement variability of HbA1c – than a true-positive test, attributable to the change over time in glycaemic control,’ the researchers concluded.
‘Annual monitoring gives more time for a meaningful change to occur in HbA1c.’

1 comment:

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