The importance of confirming screening test results for diabetes and hypertension

Simon Collins, HIV i-Base

A study from South Africa involving more than 18,000 participants reported that referrals for diabetes mellitus and hypertension were reduced by 48% and 66%, respectively, when single screening results were confirmed by a second test,

This was part of a community study looking at the positive predictive values (PPV) of a single screening result of glycated haemoglobin A1c (HbA1c) above 6.5% and the World Health Organization STEPS protocol above 140/90 mmHg respectively at the initial screen.

Results from the abstract include: “Of 18,027 participants enrolled, 10.2% (1,831) had a screening BP over 140/90 mmHg. Of those without a prior diagnosis, 871 (47.6%) received follow-up measurements. Only 51.2% (451) of those with completed follow-up measurements had a repeat BP>140/90 mmHg at the home visit and were referred to care. To achieve a 90% correct referral rate, a systolic BP threshold of 192 was needed at first screening. For DM screening, 1,615 (9.0%) individuals had an HbA1c > 6.5%, and of those without a prior diagnosis, 1,151 (71.2%) received a follow-up blood glucose. Of these, only 34.1% (395) met criteria for referral for DM. To ensure a 90% positive predictive value i.e. a screening HbA1c of >16.6% was needed.”

 Reference

Olivier S et al for the Vukuzai study team. Pitfalls of single measurement screening for diabetes and hypertension in community-based settings. Global Heart. 2021; 16(1): 79. DOI: 10.5334/gh.1083. (3 December 2021).
https://globalheartjournal.com/articles/10.5334/gh.1083