Dataset Information

Association of Sickle Cell Trait With Hemoglobin A1c in African Americans.

ABSTRACT: Hemoglobin A1c (HbA1c) reflects past glucose concentrations, but this relationship may differ between those with sickle cell trait (SCT) and those without it.To evaluate the association between SCT and HbA1c for given levels of fasting or 2-hour glucose levels among African Americans.Retrospective cohort study using data collected from 7938 participants in 2 community-based cohorts, the Coronary Artery Risk Development in Young Adults (CARDIA) study and the Jackson Heart Study (JHS). From the CARDIA study, 2637 patients contributed a maximum of 2 visits (2005-2011); from the JHS, 5301 participants contributed a maximum of 3 visits (2000-2013). All visits were scheduled at approximately 5-year intervals. Participants without SCT data, those without any concurrent HbA1c and glucose measurements, and those with hemoglobin variants HbSS, HbCC, or HbAC were excluded. Analysis of the primary outcome was conducted using generalized estimating equations (GEE) to examine the association of SCT with HbA1c levels, controlling for fasting or 2-hour glucose measures.Presence of SCT.Hemoglobin A1c stratified by the presence or absence of SCT was the primary outcome measure.The analytic sample included 4620 participants (mean age, 52.3 [SD, 11.8] years; 2835 women [61.3%]; 367 [7.9%] with SCT) with 9062 concurrent measures of fasting glucose and HbA1c levels. In unadjusted GEE analyses, for a given fasting glucose, HbA1c values were statistically significantly lower in those with (5.72%) vs those without (6.01%) SCT (mean HbA1c difference, -0.29%; 95% CI, -0.35% to -0.23%). Findings were similar in models adjusted for key risk factors and in analyses using 2001 concurrent measures of 2-hour glucose and HbA1c concentration for those with SCT (mean, 5.35%) vs those without SCT (mean, 5.65%) for a mean HbA1c difference of -0.30% (95% CI, -0.39% to -0.21%). The HbA1c difference by SCT was greater at higher fasting (P?=?.02 for interaction) and 2-hour (P?=?.03) glucose concentrations. The prevalence of prediabetes and diabetes was statistically significantly lower among participants with SCT when defined using HbA1c values (29.2% vs 48.6% for prediabetes and 3.8% vs 7.3% for diabetes in 572 observations from participants with SCT and 6877 observations from participants without SCT; P<.001 for both comparisons).Among African Americans from 2 large, well-established cohorts, participants with SCT had lower levels of HbA1c at any given concentration of fasting or 2-hour glucose compared with participants without SCT. These findings suggest that HbA1c may systematically underestimate past glycemia in black patients with SCT and may require further evaluation.

SUBMITTER: Lacy ME

PROVIDER: S-EPMC5713881 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Association of Sickle Cell Trait With Hemoglobin A1c in African Americans.

Lacy Mary E ME Wellenius Gregory A GA Sumner Anne E AE Correa Adolfo A Carnethon Mercedes R MR Liem Robert I RI Wilson James G JG Sacks David B DB Jacobs David R DR Carson April P AP Luo Xi X Gjelsvik Annie A Reiner Alexander P AP Naik Rakhi P RP Liu Simin S Musani Solomon K SK Eaton Charles B CB Wu Wen-Chih WC

JAMA 20170201 5

<h4>Importance</h4>Hemoglobin A1c (HbA1c) reflects past glucose concentrations, but this relationship may differ between those with sickle cell trait (SCT) and those without it.<h4>Objective</h4>To evaluate the association between SCT and HbA1c for given levels of fasting or 2-hour glucose levels among African Americans.<h4>Design, setting, and participants</h4>Retrospective cohort study using data collected from 7938 participants in 2 community-based cohorts, the Coronary Artery Risk Developmen ...[more]

PMID: 28170479

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Project description:The association between sickle cell trait (SCT) and chronic kidney disease (CKD) is uncertain.To describe the relationship between SCT and CKD and albuminuria in self-identified African Americans.Using 5 large, prospective, US population-based studies (the Atherosclerosis Risk in Communities Study [ARIC, 1987-2013; n?=?3402], Jackson Heart Study [JHS, 2000-2012; n?=?2105], Coronary Artery Risk Development in Young Adults [CARDIA, 1985-2006; n?=?848], Multi-Ethnic Study of Atherosclerosis [MESA, 2000-2012; n?=?1620], and Women's Health Initiative [WHI, 1993-2012; n?=?8000]), we evaluated 15,975 self-identified African Americans (1248 participants with SCT [SCT carriers] and 14,727 participants without SCT [noncarriers]).Primary outcomes were CKD (defined as an estimated glomerular filtration rate [eGFR] of <60 mL/min/1.73 m2 at baseline or follow-up), incident CKD, albuminuria (defined as a spot urine albumin:creatinine ratio of >30 mg/g or albumin excretion rate >30 mg/24 hours), and decline in eGFR (defined as a decrease of >3 mL/min/1.73 m2 per year). Effect sizes were calculated separately for each cohort and were subsequently meta-analyzed using a random-effects model.A total of 2233 individuals (239 of 1247 SCT carriers [19.2%] vs 1994 of 14,722 noncarriers [13.5%]) had CKD, 1298 (140 of 675 SCT carriers [20.7%] vs 1158 of 8481 noncarriers [13.7%]) experienced incident CKD, 1719 (150 of 665 SCT carriers [22.6%] vs 1569 of 8249 noncarriers [19.0%]) experienced decline in eGFR, and 1322 (154 of 485 SCT carriers [31.8%] vs 1168 of 5947 noncarriers [19.6%]) had albuminuria during the study period. Individuals with SCT had an increased risk of CKD (odds ratio [OR], 1.57 [95% CI, 1.34-1.84]; absolute risk difference [ARD], 7.6% [95% CI, 4.7%-10.8%]), incident CKD (OR, 1.79 [95% CI, 1.45-2.20]; ARD, 8.5% [95% CI, 5.1%-12.3%]), and decline in eGFR (OR, 1.32 [95% CI, 1.07-1.61]; ARD, 6.1% [95% CI, 1.4%-13.0%]) compared with noncarriers. Sickle cell trait was also associated with albuminuria (OR, 1.86 [95% CI, 1.49-2.31]; ARD, 12.6% [95% CI, 7.7%-17.7%]).Among African Americans in these cohorts, the presence of SCT was associated with an increased risk of CKD, decline in eGFR, and albuminuria, compared with noncarriers. These findings suggest that SCT may be associated with the higher risk of kidney disease in African Americans.

Project description:ImportanceAfrican Americans and individuals of African ancestry have a higher risk of stroke compared with non-Hispanic white individuals. Identifying the source of this disparity could provide an opportunity for clinical stroke risk stratification and more targeted therapy. Whether sickle cell trait (SCT) is an indicator of increased risk of ischemic stroke among African Americans is still unclear.ObjectiveTo examine whether SCT is associated with a higher risk of incident ischemic stroke among African Americans.Design, setting, and participantsThis meta-analysis assessed the association of SCT with the risk of incident ischemic stroke. Four large, prospective, population-based studies with African American cohorts were assessed: Jackson Heart Study (September 1, 2005, through December 31, 2012), Multi-Ethnic Study of Atherosclerosis (July 1, 2002, through December 31, 2012), Reasons for Geographic and Racial Differences in Stroke (January 1, 2003, through December 31, 2014), and Women's Health Initiative (October 1, 1998, through December 31, 2012). Using a Cox proportional hazards regression model adjusted for major stroke risk factors, this study estimated the hazard ratio for incident ischemic stroke associated with SCT. Data analysis was performed from July 10, 2016, to February 2, 2017.Interventions or exposuresParticipants' SCT status determined by polymerase chain reaction assay genotyping or a combination of whole-exome sequencing and imputation.Main outcomes and measuresIncident ischemic stroke.ResultsThis meta-analysis included 19 464 African American individuals (1520 with SCT, 17 944 without SCT, and 620 with ischemic stroke) from 4 studies, with a mean (SD) age of 60.0 (13.0) years (5257 [27.0%] men and 14 207 [73.0%] women). No differences were found in the distribution of risk factors for ischemic stroke comparing participants with and those without SCT at study visit 1 in each cohort. The crude incidence of ischemic stroke was 2.9 per 1000 person-years (95% CI, 2.2-4.0 per 1000 person-years) among those with SCT and 3.2 per 1000 person-years (95% CI, 2.7-3.8 per 1000 person-years) among those without SCT. After stroke risk factors were adjusted for, the hazard ratio of incident ischemic stroke independently associated with SCT in the meta-analysis of all 4 cohorts was 0.80 (95% CI, 0.47-1.35; P = .82). The results of the meta-analysis were similar to those of individual cohorts, in which the results were also similar.Conclusions and relevanceSickle cell trait may not be associated with incidence of ischemic stroke among African Americans. The results of this study suggest performing a more thorough clinical evaluation of a stroke patient with SCT rather than assuming that SCT is the etiologic factor for the stroke.

Dataset Information

Association of Sickle Cell Trait With Hemoglobin A1c in African Americans.

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Association of Sickle Cell Trait With Hemoglobin A1c in African Americans.

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