Sex differences in chronic kidney disease awareness among US adults, 1999 to 2018

Abstract

Background: Chronic kidney disease (CKD) is less prevalent among men than women, but more men than women initiate kidney replacement therapy. Differences in CKD awareness may contribute to this gender gap, which may further vary by race/ethnicity. We aimed to investigate trends in CKD awareness and the association between individual characteristics and CKD awareness among US men versus women.

Methods and findings: We conducted a serial, cross-sectional analysis of 10 cycles (1999-2018) from the National Health and Nutrition Examination Survey (NHANES). Adult participants with CKD stages G3-G5 (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73m2) were included, unless they were on dialysis or medical information was missing. Serum creatinine was measured during NHANES medical exams. CKD stage was classified by eGFR, based on the CKD-EPI formula. CKD awareness was assessed with the question: "Have you ever been told by a health care professional you had weak or failing kidneys", asked in standardized NHANES questionnaires on each survey. Using logistic regression models, we evaluated the association between sex and CKD awareness, adjusting for potential confounders including age, race/ethnicity and comorbidities. We stratified CKD awareness by 5 pre-defined calendar-year periods and conducted all analyses for the complete study population as well as the Caucasian and African American subpopulations. We found that among 101871 US persons participating in NHANES, 4411 (2232 women) had CKD in stages G3-G5. These participants were, on average, 73±10 years old, 25.3% reported diabetes, 78.0% reported hypertension or had elevated blood pressure during medical examinations and 39.8% were obese (percentages were survey-weighted). CKD awareness was more prevalent among those with higher CKD stage, younger age, diabetes, hypertension and higher body mass index. CKD awareness was generally low (<22.5%), though it increased throughout the study period, remaining consistently higher among men compared to women, with a decreasing gender gap over time (adjusted odds ratio [men-to-women] for CKD awareness = 2.71 [1.31-5.64] in period 1; = 1.32 [0.82-2.12] in period 5). The sex difference in CKD awareness was smaller in African American participants, in whom CKD awareness was generally higher. Using serum creatinine rather than eGFR as the CKD-defining exposure, CKD awareness increased with rising serum creatinine, in a close to identical fashion among both sexes during 1999-2008, while during 2009-2018, CKD awareness among women increased earlier than among men (i.e. with lower serum creatinine levels).

Conclusions: CKD awareness is lower among US women than men. The narrowing gap between the sexes in more recent years and the results on CKD awareness by serum creatinine indicate that health care professionals have previously been relying on serum creatinine to inform patients about their condition, but in more recent years have been using eGFR, which accounts for women's lower serum creatinine levels due to their lower muscle mass. Additional efforts should be made to increase CKD awareness among both sexes.

Fig 1. Flow chart of the study sample.

Fig 2. Association of chronic kidney disease awareness and patient characteristics.

Association of chronic kidney disease (CKD) awareness by sex with period, CKD stage, age group, Diabetes Mellitus (DM), Hypertension (HT) and BMI in all NHANES participants (A), Caucasians (B) and African Americans (C), 1999–2018; Odds ratios were adjusted for all other characteristics shown, odds ratios for all participants (A) were further adjusted for race/ethnicity. The numerical values for these odds ratios and 95% confidence intervals are shown in supporting information S3 Table.

Fig 3. Chronic kidney disease awareness of men versus women over time.

Chronic kidney disease (CKD) awareness of men versus women in NHANES 1999–2018 of all study participants (A), Caucasians (B) and African Americans (C); (top) Unadjusted CKD awareness over time with 95% confidence interval (bottom) CKD awareness odds ratios of men versus women by year with 95% confidence interval; Odds ratios were adjusted for CKD disease stage, age, diabetes, hypertension and BMI; Odds ratios for all study participants were further adjusted for race/ethnicity.

Fig 4. Chronic kidney disease awareness of men versus women by creatinine.

Chronic kidney disease awareness of men versus women in NHANES 1999–2008 and 2009–2018, by creatinine interval, of all study participants (A), Caucasians (B) and African Americans (C).