Pitfalls of Single Measurement Screening for Diabetes and Hypertension in Community-Based Settings
Stephen Olivier,
Thomas Murray,
Philippa Matthews,
Ngcebo Mhlongo,
Resign Gunda,
Kathy Baisley,
Dickman Gareta,
Tshwaraganang Modise,
Theresa Smit,
Kobus Herbst,
Xolile Mpofana,
Thumbi Ndung’u,
Olivier Koole,
Deenan Pillay,
Willem Hanekom,
Emily Wong,
Mark J. Siedner,
Vukuzazi Study team
Affiliations
Stephen Olivier
Africa Health Research Institute, KwaZulu-Natal
Thomas Murray
Africa Health Research Institute, KwaZulu-Natal
Philippa Matthews
Africa Health Research Institute, KwaZulu-Natal, ZA; Islington GP Federation, London
Ngcebo Mhlongo
Africa Health Research Institute, KwaZulu-Natal
Resign Gunda
Africa Health Research Institute, KwaZulu-Natal
Kathy Baisley
Africa Health Research Institute, KwaZulu-Natal, ZA; London School of Hygiene and Tropical Medicine, London
Dickman Gareta
Africa Health Research Institute, KwaZulu-Natal
Tshwaraganang Modise
Africa Health Research Institute, KwaZulu-Natal
Theresa Smit
Africa Health Research Institute, KwaZulu-Natal
Kobus Herbst
Africa Health Research Institute, KwaZulu-Natal; DSI-MRC South African Population Research Infrastructure Network (SAPRIN), Durban
Xolile Mpofana
Africa Health Research Institute, KwaZulu-Natal
Thumbi Ndung’u
Africa Health Research Institute, KwaZulu-Natal; HIV Pathogenesis Programme, The Doris Duke Medical Research Institute, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, ZA; Max Planck Institute for Infection Biology, Berlin, DE; Division of Infection and Immunity, University College London, London
Olivier Koole
Africa Health Research Institute, KwaZulu-Natal, ZA; London School of Hygiene and Tropical Medicine, London
Deenan Pillay
Africa Health Research Institute, KwaZulu-Natal, ZA; Division of Infection and Immunity, University College London, London
Willem Hanekom
Africa Health Research Institute, KwaZulu-Natal, ZA; Division of Infection and Immunity, University College London, London
Emily Wong
Africa Health Research Institute, KwaZulu-Natal, ZA; Division of Infectious Diseases, University of Alabama Birmingham, Birmingham, AL
Mark J. Siedner
Africa Health Research Institute, KwaZulu-Natal, ZA; Harvard Medical School, Boston, MA
Background: Cross-sectional screening programs are used to detect and refer individuals with non-communicable diseases to healthcare services. We evaluated the positive predictive value of cross-sectional measurements for Diabetes Mellitus (DM) and hypertension (HTN) as part of a community-based disease screening study, ‘Vukuzazi’ in rural South Africa. Methods: We conducted community-based screening for HTN and DM using the World Health Organization STEPS protocol and glycated haemoglobin A1c (HbA1c) testing, respectively. Nurses conducted follow-up home visits for confirmatory diagnostic testing among individuals with a screening BP above 140/90 mmHg and/or HbA1c above 6.5% at the initial screen, and without a prior diagnosis. We assessed the positive predictive value of the initial screening, compared to the follow up measure. We also sought to identify a screening threshold for HTN and DM with greater than 90% positive predictive value. Results: 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. Conclusions: A second home-based screening visit to confirm a diagnosis of DM and HTN reduced health system referrals by 48% and 66%, respectively. Two-day screening programmes for DM and HTN screening might save individual and healthcare resources and should be evaluated carefully in future cost effectiveness evaluations.
