Disparities in cardio metabolic risk between Black and White women with polycystic ovary syndrome: a systematic review and meta-analysis

Objective

We conducted a systematic review and meta-analysis to summarize and quantitatively pool evidence on cardiometabolic health disparities between Black and White women with polycystic ovary syndrome in the United States in response to the call for further delineation of these disparities in the international evidence-based guideline for the assessment and management of polycystic ovary syndrome.

Data Sources

Databases of MEDLINE, Web of Science, and Scopus were searched initially through March 05, 2020, and confirmed on September 11, 2020.

Study Eligibility Criteria

Observational studies documenting cardiometabolic risk profile (glucoregulatory, lipid profile, anthropometric, and blood pressure status) in Black and White women with polycystic ovary syndrome were included. Studies on children (<17 years old) and pregnant or menopausal-aged women (>50 years) were excluded. The primary outcome was fasting glucose. Furthermore, data on major cardiovascular events (stroke, coronary heart disease, heart failure) and mortality rate (cardiovascular death, total mortality) were evaluated.

Methods

Data were pooled by random-effects models and expressed as mean differences and 95% confidence intervals. Studies were weighted based on the inverse of the variance. Heterogeneity was evaluated by Cochran Q and I² statistics. Study methodologic quality was assessed by the Newcastle-Ottawa scale.

Results

A total of 11 studies (N=2851 [652 Black and 2199 White]) evaluated cardiometabolic risk profile and all had high quality (Newcastle-Ottawa scale score of ≥8). No studies reported on cardiovascular events and mortality rate. Black women had comparable fasting glucose (−0.61 [−1.69 to 2.92] mg/dL; I²=62.5%), yet exhibited increased fasting insulin (6.76 [4.97–8.56] μIU/mL; I²=59.0%); homeostatic model assessment of insulin resistance (1.47 [0.86–2.08]; I²=83.2%); systolic blood pressure (3.32 [0.34–6.30] mm Hg; I²=52.0%); and decreased triglyceride (−32.56 [−54.69 to −10.42] mg/dL; I²=68.0%) compared with White women (all, P≤.03). Groups exhibited comparable total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and diastolic blood pressure (all, P≥.06).

Conclusions

Black women with polycystic ovary syndrome have a greater tendency for an adverse cardiometabolic risk profile (increased insulin, homeostatic model assessment of insulin resistance, and systolic blood pressure) despite lower triglycerides than White women. Our observations support the consideration of these disparities for diagnostic, monitoring, and management practices in Black women and for future guideline recommendations. Given the heterogeneity among studies, future research should address the relative contributions of biologic, environmental, socioeconomic, and healthcare factors to the observed disparities. Furthermore, longitudinal research is required to address patient-pressing complications, including cardiovascular events and mortality rate in Black women with polycystic ovary syndrome as a high-risk yet understudied population.

Introduction

Women with polycystic ovary syndrome (PCOS) exhibit an adverse cardiometabolic risk profile compared with their counterparts without PCOS.1, 2, 3 Poor glucoregulatory status, characterized by abnormal glucose and insulin levels secondary to insulin resistance (IR), is the key pathophysiological factor associated with a wide range of metabolic disruptions in PCOS.^2,4,5 Although the true risk of cardiovascular mortality remains unclear in this clinical population,⁶ the theoretical risk is substantial and warrants consideration of treatment and prevention strategies given both short- and long-term implications of cardiometabolic aberrations on pregnancy outcomes, lifelong health, and wellness.

AJOG at a Glance

We aimed to evaluate cardiometabolic health disparities between Black and White women with polycystic ovary syndrome (PCOS) in the United States.

Black women with PCOS have a greater tendency for adverse cardiometabolic risk profiles, evidenced by increased insulin, insulin resistance, and systolic blood pressure, despite lower triglyceride levels than White women.

This is the first systematic review to show a disproportionate cardiometabolic risk burden among Black women with PCOS in the United States. Our findings support the need to address health disparities in current clinical practice, future guideline development, and longitudinal research evaluating cardiovascular events and mortality rate in Black women with PCOS as a high-risk understudied population.

The degree to which cardiometabolic aberrations may disproportionately impact diverse populations of women with PCOS is important yet understudied. We and others have shown differences in cardiovascular risk factors, metabolic syndrome (MetS) rate, prediabetes, and type 2 diabetes status across diverse populations of women with PCOS in the United States and worldwide, supporting the potential for cardiometabolic health disparities in Indigenous, South Asian, Middle Eastern, and Black women compared with White or Caucasian counterparts.10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 7, 8, 9 The recent international evidence-based guideline for the assessment and management of PCOS emphasizes the need to further delineate these disparities to inform targeted diagnosis, monitoring, and management of high-risk clinical populations and subsequent adaptations of the guideline recommendations across geographic regions and clinical settings.²⁶ Although the guideline recommends that health professionals consider presentation and manifestations of PCOS across diverse populations,²⁶ our knowledge about the presence and magnitude of cardiometabolic health disparities is far from complete and remains to be elucidated.

In the United States, our knowledge about health disparities in the context of PCOS is limited to a few cross-sectional analyses that have yielded inconsistent results. Black or African Americans are a large underrepresented group in the United States. According to the Census Bureau (2019) data, approximately 44 million people in the United States are Black alone, representing 13.4% of the total population.²⁷ However, Black women with PCOS are understudied, and their cardiometabolic characteristics have yielded conflicting results compared with their White counterparts. Some studies reported a worse cardiometabolic profile in Black compared with White women with PCOS, as evidenced by increased fasting glucose,¹⁴ increased fasting insulin,^8,9,11,13, 14, 15^,17,20 elevated systolic blood pressure (SBP)^7,8,14 and diastolic blood pressure (DBP),^7,14 decreased high-density lipoprotein cholesterol (HDL-C),^7,14 and increased MetS rate.^7,14 Conversely, others showed no differences between these groups in fasting glucose,^{7,9,11,13,16,17} fasting insulin,^16,18,19 SBP,^10,17, 18, 19, 20 DBP,^10,17, 18, 19, 20 total cholesterol (TC),^12,15,17 low-density lipoprotein cholesterol (LDL-C),^8,17,19 HDL-C,^8,10,12 waist circumference (WC),^9,10,18 and waist to hip ratio.^11,12 To complicate matters, there is even evidence to support that Black women with PCOS have a more favorable cardiometabolic profile than White women, as assessed by decreased TC,^8,14 increased HDL-C,^15,17 decreased LDL-C,¹² and triglyceride (TG).^{7,10,12,14,15,17}

The inconsistency may stem, in part, from the small sample sizes of individual studies, which have limited their statistical power to capture health disparities in cardiometabolic outcomes. Difficulties in establishing accurate PCOS status owing to reliance on self-reported diagnosis and unreliable measures of androgen status²⁸ and ovarian morphology29, 30, 31 may have also contributed. The use of retrospective data and failure to account for variations in age, adiposity, lifestyle, and socioeconomic status across studies may have led to inconsistent findings. Furthermore, data regarding cardiovascular events (eg, nonfatal stroke, myocardial infarction, and heart failure), cardiovascular mortality, or total mortality are sparse in Black women with PCOS. Collectively, whether Black and White women with PCOS exhibit cardiometabolic risk differences remains unknown yet is critical for sustainable and successful management strategies that set the foundation for achieving health equity in this clinical population.³²

To address this knowledge gap, we conducted a systematic review and meta-analysis to characterize cardiometabolic health disparities between Black and White women with PCOS in the United States. Our primary aim was to assess whether Black women with PCOS exhibited worse glucoregulatory status, as assessed by increased fasting glucose, than White women. As our secondary aim, we evaluated whether other cardiometabolic risk factors (glucoregulatory [insulin, IR], anthropometric, lipid profile, and blood pressure status), major cardiovascular events (stroke, coronary heart disease, and heart failure), and the mortality rate (cardiovascular death and total mortality) were exacerbated in Black women with PCOS than their White counterparts. Our focus on these cohorts is relevant because data from the general population have shown a substantial and persistent risk for cardiovascular disease and type 2 diabetes morbidity and or mortality in Black vs White cohorts,^33,34 which could manifest early in reproductive-aged women with PCOS with underlying metabolic complications, warranting early preventative and management modalities. We hypothesized that Black women with PCOS would exhibit increased glucoregulatory dysregulation (increased glucose, IR, and hyperinsulinemia) and an overall worse cardiometabolic risk compared with White women with PCOS.