Gender Disparity in Hemodialysis Practices and Mortality: A Nationwide Cross-Sectional Observational Study

Introduction

In the general population,¹ women tend to have higher survival rates than men, which may be attributable to their lower occurrence of cardiovascular risk factors and diseases.^2,3 Recognized physiological differences between genders may contribute to reported disparities in various diseases, including type 2 diabetes, cardiovascular disease, depression, and various stages of kidney disease.^4-13 The progression rate of numerous kidney disorders is influenced by gender, a topic that has been extensively examined in more comprehensive reviews.¹⁴ The largest meta-analysis conducted to date, encompassing over 11,000 patients from 68 different studies, has shown that women with conditions such as polycystic kidney disease, IgA nephropathy, membranous nephropathy, and ‘chronic kidney disease of unknown etiology’ tend to experience a slower progression of kidney disease compared to men with matching blood pressure and lipid levels who have these conditions.¹⁵ More recently, two additional population-based studies have also revealed that men exhibit a slower chronic kidney disease (CKD) progression compared to women.^16,17 Previous observational studies from the Dialysis Outcomes and Practice Patterns Study (DOPPS)¹⁸ and the Austrian Dialysis Registry,¹⁹ have shown no difference in survival between men and women. The present study aims to perform gender-specific analysis of maintenance hemodialysis (MHD) practices and mortality.

Materials and Methods

A nationwide cross-sectional study was conducted in India among patients undergoing MHD in 203 centers provided by a single large network-Nephroplus. There were a total of 9 (4.43%) standalone centers and 194 (95.57%) were part of an institution/hospital. Region-wise distribution of centers is provided in Table 1. Data was collected retrospectively from the hospital management information system and electronic medical records. All adult (>18 years) patients receiving MHD from January 1, 2021 to March 31 2021 were included. Patients who died were identified and an equal number of survivors were randomly selected from the total dialysis population in the dialysis network. We excluded patients on HD for less than 90 days, aged less than 18 years, and deaths due to COVID-19 infection. The patients who died during this period were considered as cases and those who survived were taken as controls [Figure 1]. We stratified the non-survivors (cases) and survivors (controls) by gender to identify gender-specific risk factors for death.

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Figure 1:

Methodology for selection of cases and controls for the study.

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Data on demographic factors, dialysis, educational status, and dialysis payer type (public insurance, out-of-pocket payment, or private insurance) were collected. HD facilities were classified by funding model as public–private partnerships (PPP) or private. PPP is a setup where the government pays for HD in a private dialysis center. Dialysis-related factors included dialysis vintage, frequency of weekly HD sessions, vascular access type, dialysis adequacy (measured online in Fresenius 4008 S machines), hemoglobin, erythropoietin use, and serum albumin levels. Additionally, the cause of CKD (diabetic or non-diabetic), and comorbidities including hypertension, history of heart failure, and any hospitalizations in the past 3 months were also documented. Ethical approval for this study was waived by the Institutional Ethics Committee of The George Institute for Global Health India. This is due to our exclusive use of deidentified data from patients who had voluntarily consented to its use for clinical research at the time of registration at a NephroPlus centre, before any data was collected. A refusal to consent did not impact a patient’s right to receive treatment, which was made clear to patients from the outset.

Discussion

This is the first study from India, exploring factors associated with mortality among both the genders in patients undergoing maintenance hemodialysis. Earlier studies from dialysis cohorts^25,26 showed that the life expectancy of women is not higher than men. While men generally show higher death rates than women in the overall population, DOPPS¹⁴ has shown equivalent mortality rates for both sexes, with the ratio near unity across all DOPPS countries, except Japan. Factors, including ethnic diversity, and disparities in healthcare access may influence the outcome.^27–29 The greater impact of a higher BMI on the survival of male dialysis patients compared to female patients may be attributed to men having more skeletal muscle mass and less fat mass due to male sex hormones.^30,31

Women had a significantly lower educational status than men and lower literacy level was associated with mortality in both genders. A systematic review of 29 studies showed that limited health literacy was found to be a significant and independent predictor of hospital admissions, emergency department visits, skipped dialysis treatments, cardiovascular incidents, and deaths.³² Yet, when literacy levels are compared between genders, a significant disparity is evident, with a noticeable difference in literacy rates between men and women in India.^33,34

The requirement of out-of-pocket expenditure and use of temporary access for initiation of HD are significantly higher in females. The outcomes of this research align with those found in previous studies on healthcare expenditure (HCE) in India and certain Asian nations,^34,35 but they diverge from findings in numerous developed and developing countries.^36,37 Typically, women in developed countries possess greater health awareness, make more use of health services and preventive measures, and consequently spend more on their health care compared to those from developing countries.³⁸ However, in nations like India and China, a tangled mix of poverty and societal stratification, often pushes women’s health down the list of household priorities, leading women to allocate more time to domestic or non-income-generating work.³⁹ This could be the reason for women not being enrolled into state-sponsored or private insurance cover. Also, women may delay addressing their health needs to cater to the needs of the income-earning male members of the family and often give precedence to the health of males over their own⁴⁰ which may potentially result in loss to follow-up, unable to buy medications, non-compliant to medications, failure to create AV fistula before progressing to end stage kidney disease and ending up with the requirement of temporary access for initiation of HD (urgent start HD). Therefore, the gender disparity in HCE in India might be due to the intersection of socioeconomic factors and patriarchal traditions.⁴¹

In this study, IHD was significantly more common in men than women. This is in concordance with previous data. Typically, women have a lower occurrence of IHD than men, except those who are 65 years old and above. As women reach menopause, the disparity in IHD onset between genders narrows, leading to a higher incidence in older women. The post-poned development of IHD in women might be due to the protective effects of natural estrogen and the hormonal shifts associated with menopause.⁴²

There was no difference with respect to serum albumin levels, dialysis duration, frequency, and adequacy between the genders. This suggests that there was no difference between the genders in the quality of treatment delivered, which is similar to previous studies.^43,44 These previous studies showed that there was no gender difference in self-care efficacy among HD population.

The current study is subject to a few limitations. Firstly, the findings of this study demonstrate a correlation between factors associated with mortality in dialysis patients, but they do not establish a cause-and-effect relationship. Secondly, it was a cross-sectional data collection. Hence, variables like BMI, comorbidity status, and lab results, may vary with time. Thirdly, the southern states of India consistently excel compared to the rest of the nation in terms of health, education, and economic prospects.⁴⁵ Disproportionately higher representation of the South Indian population in this study could have confounded the observations. Fourthly, the sample size of women being much smaller than the men is bound to have confounded association of some factors with mortality as in men in this population. Lastly, the sex of the participants was recorded from medical records, without accounting for transgender or non-binary individuals.

Males predominated on maintenance hemodialysis. Females were less educated, required temporary HD catheters for initiation, and less likely to be paid for by public or private health insurance cover compared to males. Hypertension and IHD were significantly more prevalent in males, while diabetes as the cause of kidney failure was more prevalent in females. Multivariate analysis demonstrated that lower educational status, hypoalbuminemia, previous history of hospitalization (last 3 months), and dialysis in centers run by PPP were associated with mortality in males. Lower educational status, heart failure, and previous history of hospitalization were associated with mortality in females.