High Rates of Undiagnosed Target Organ Damage Among Adults with Elevated Blood Pressure or Diabetes Mellitus in a Community-Based Survey in Lesotho

INTRODUCTION

Prevalence of elevated blood pressure (BP) and diabetes mellitus (DM) is increasing in sub-Saharan Africa. Data on target organ damage such as retinopathy, left ventricular hypertrophy (LVH), renal impairment and peripheral neuropathy (PN) among persons with elevated BP and/or DM in sub-Saharan Africa remain scarce.

AIM

To determine at community-level the prevalence of retinopathy, LVH, renal impairment, and PN among adults with elevated BP and/or DM, and assess the association of elevated BP and/or DM with target organ damage in Lesotho.

METHODS

During a household-based survey, a sub-sample of adults with elevated BP (≥ 140/90 mmHg) and/or DM (glycosylated hemoglobin ≥ 6.5%), as well as comparators (BP < 140/90 mmHg, HbA1c < 6.5%) were screened for retinopathy, LVH, renal impairment, and PN. We used multivariable logistic regression for inferential analysis.

RESULTS

Out of 6108 participants screened during the survey, 420 with elevated BP only, 80 with DM only, 61 with elevated BP and DM, and 360 comparators were assessed for target organ damage. Among those with elevated BP, and among those with DM with or without elevated BP, prevalence of retinopathy was 34.6% (89/257) and 14.4% (15/104); renal impairment was 45.0% (156/347) and 42.4% (56/132), respectively. Among those with elevated BP, 2.3% (7/300) and 65.7% (224/341) had LVH and left ventricular concentric remodeling, respectively. PN, only assessed among those with DM, was present in 32.6% (42/129). Elevated BP was associated with increased odds of retinopathy (aOR, 19.13; 95% CI, 8.52-42.94; P < 0.001) and renal impairment (aOR, 1.80; 95% CI, 1.27-2.55; P = 0.001). Presence of both elevated BP and DM was associated with an increased odds of retinopathy (aOR, 16.30; 95%CI, 5.69-46.68; P < 0.001), renal impairment (aOR, 2.55; 95% CI, 1.35-4.81; P = 0.004), and PN (aOR, 2.13; 95% CI, 1.04-4.38; P = 0.040).

CONCLUSION

We found a high prevalence of undiagnosed target organ damage among adults with elevated BP and/or DM during community-based screening. These findings emphasize the importance of regular prevention and screening activities in this setting.

Head-to-head comparison of the WHO STEPwise approach with immediate unattended and delayed unattended automated blood pressure measurements during household-based screening: a diagnostic accuracy study in Lesotho

Background

WHO introduced the STEPwise approach to surveillance (STEPS) to monitor trends in non-communicable diseases. For arterial hypertension, the STEPS protocol takes the average of the last two out of three standard blood pressure measurements (SBPM). This study assesses the diagnostic accuracy of SBPM, same-day and next-day unattended automated measurement (uABP), with 24 h ambulatory measurement (24 h-ABPM) as reference.

Methods

This diagnostic accuracy study was done within a population-based household survey on cardiovascular risk factors in two districts in Northern Lesotho. Adults (aged ≥ 18 years) with elevated SBPM (defined as ≥140/90 mmHg), and 2:1 age- and sex-matched participants with normal SBPM during the survey were recruited. Following SBPM, first uABP readings were obtained on survey day. Afterwards, participants received a 24 h-ABPM device. Second uABP readings were taken 24 h later, after retrieval of the 24 h-ABPM. The main outcome was overall diagnostic accuracy of all screening measurements (SBPM, first uABP, and second uABP), determined using area under the receiver operating characteristic curve (AUROC), with 24 h-ABPM as a reference.

Findings

Between November 2, 2021 and August 31, 2022, 275 participants (mean age 58 years (SD: 16 years), 163 (59%) female) were enrolled, 183 of whom had elevated and 92 had normal SBPM. Mean difference between systolic daytime 24 h-ABPM and screening measurements was highest for SBPM (mean difference: -13 mmHg; 95% CI: -14 to -11). Mean difference between diastolic daytime 24 h-ABPM and diastolic SBPM was -2 mmHg (95% CI: -4 to -1), whereas no difference was found for mean diastolic first uABP (mean difference: -1 mmHg; 95% CI: -2.0 to 0.3); and mean diastolic second uABP (mean difference: 1.0 mmHg; 95% CI: -0.4 to 2.3). White coat hypertension was highest with SBPM (55 [20%]), followed by first uABP (27 [9.8%]), and second uABP (18 [6.5%]). Using systolic daytime 24 h-ABPM as a reference, the uABPs had higher AUROC (first uABP: 87% [95% CI: 83-91]; second uABP: 88% [95% CI: 84-92]); SBPM: (79% [95% CI: 74-85]). This difference was significant between first uABP and SBPM (P = 0.0024), and between second uABP and SBPM (P = 0.0017).

Interpretation

uABP had better diagnostic performance than SBPM. Integration of uABP into STEPS protocol should be considered.

Funding

Swiss Agency for Development and Cooperation under the ComBaCaL project, and the World Diabetes Foundation.