Access to sanitation and gynecologic health: a time-to-event analysis of hysterectomy before age 40 yearsGrace C. Hohnadel1 and Biplab Kumar Datta2,3*1 Medical College of Georgia, Augusta University, Augusta, GA, USA. 2 Institute of Public and Preventive Health, Augusta University, Augusta, GA, USA. 3Department of Health Management, Economics and Policy, School of Public Health, Augusta University, Augusta, GA, USA.*Corresponding author. Email: bdatta@augusta.edu. Address: 1120 15th Street, Augusta, GA 30912, United States. Tel. +1 706-721-8794.Running title: Sanitation and gynecologic healthNearly one-fifth of the Indian households do not have any toilet facilities and practice open defecation.1 Women are particularly vulnerable to limited sanitation access due to concerns including lack of privacy and being victims of sexual violence,2 along with other factors such as unclean environment, absence of water, and exposure to the elements. Consequently, many women limit urination and defecation, to early morning and late evening to avoid visibility and thereby to reduce the risk of sexual assult.3 Such practice, coupled with unhygienic environments, can severely impact women’s gynecologic health. This study aims to assess the potential influence of not having a toilet facility on adverse gynecologic health outcomes captured by the event of having a hysterectomy before the age of 40 years. While hysterectomy is more prevalent among women aged 40+ years,4 undergoing a hysterectomy before age 40 years could be regarded as a reasonable proxy for gynecologic health issues impacted by built environment such as lack of sanitation facility.Using data on self-reported age at hysterectomy from the 2015-16 and 2019-21 waves of the National Family Health Survey of India, we estimated non-parametric Kaplan-Meier (K-M) survivor functions and parametric Cox proportional hazard models for the event of hysterectomy before age 40 years. K-M survivor functions were separately estimated for the full sample and for sub-samples of never/ever married, urban/rural residence, and poor/non-poor status. Log-rank tests were performed to assess the equality of survivor functions. Based on meeting the proportional hazard assumption, educational attainment, rural region, and ever married status were included in the Cox model as covariates and religion, household wealth-index quintiles, birth year groups (e.g., 1965-1969, 2005-2009), and state of residence (e.g., Andhra Pradesh, West Bengal) were adjusted through stratification. Note that health status conditions (e.g., body mass index) were not included since those were observed at the time of the interview and not during or prior to the event of hysterectomy. Our sample was comprised of 784,862 women, aged 15-49 years, who were living in their current residence for 15+ years. Women who had hysterectomy before age 15 years, or more than 10 years ago prior to the survey, or could not recall the timing of the event, were excluded from analysis.The K-M estimates showed a significantly higher risk of hysterectomy before age 40 years among women living in households without toilet facility (Figure 1). Except for the never-married sub-group, the difference between with and without toilet facility was evident in all sub-groups. Results of the stratified Cox model suggested that women living in households without toilet facility were 1.20 (95% CI: 1.15 – 1.25) times more likely to undergo a hysterectomy before age 40 years compared to those living in households with toilet facility.These results are suggestive of a potential influence of access to sanitation on gynecologic health of reproductive-aged women. To our knowledge, this is one of the first studies to provide an estimate of the relationship between access to toilet facilities and adverse gynecologic health outcomes proxied by hysterectomy before age 40 years. A limitation of the analysis was that we could not adjust for prior health conditions that might influence hysterectomy. A notable strength, on the other hand, was that the association was assessed in a large nationally representative sample, as well as in various sociodemographic sub-sample, utilizing a time-to-event design. We, however, were unable to test any mechanisms which need to be investigated in future research. Our findings that access to sanitation, a Sustainable Development Goal, is closely related to gynecologic health, will help advancing efforts to improve sanitation access and women’s health in low resource settings.