Association of Water, Sanitation, and Hygiene-related Factors, Nutritional Status, and Sociodemographic Covariates with Urinary Iodine Concentration Levels among Filipino Women of Reproductive Age (15-49 Years): A Cross-sectional Study.

Abstract

Background and objective: Iodine deficiency (ID) remains a public health concern in the Philippines. While the country has made progress in addressing ID, pockets of deficiency persist in specific population groups, such as the Filipino women of reproductive age (WRA), whose nutritional status is critical in supporting their own health and that of their children. It has been previously shown that factors related to water, sanitation, and hygiene (WASH) are potentially associated with ID. Thus, this study was conducted to determine the association of WASH-related variables with the levels of urinary iodine concentration (UIC), the primary indicator of recent iodine intake and iodine nutrition status, among Filipino WRA.

Methods: A cross-sectional secondary analysis of nationally representative survey data was employed in this study. The data of 12,344 Filipino women aged 15-49 years old from the 2018, 2019, and 2021 Expanded National Nutrition Surveys (ENNS) were utilized and analyzed. Multiple linear regression analyses were performed to identify WASH-related factors, nutritional status, and sociodemographic covariates as predictors of UIC levels in WRA of ENNS while holding other variables constant. Adjusted regression coefficients were reported. Survey weights were not applied in the analyses as the focus of the study was on determining associations and effect estimates.

Results: Several factors were identified to be significantly associated with insufficient UIC status among the Filipino WRA, including late reproductive years, being married or having a partner, low wealth quintiles, no formal education or completion of elementary level, level 1 source of drinking water, no water treatment modalities, or the absence of an existing garbage disposal method. Upon fully adjusting for age groups, nutritional status, ethnicity, and socioeconomic status as covariates in the models, level 3 drinking water (adjusted effects = 14.02 μg/L; 95% CI: 6.28, 21.77; p <0.001), garbage disposal by a collector system (adjusted effects = 10.81 μg/L; 95% CI: 1.18, 20.44; p = 0.028), and household salt iodine concentration in ppm (adjusted effects = 0.96 μg/L; 95% CI: 0.79, 1.14; p <0.001) were significantly associated with increased UIC levels in WRA. Conversely, the use of bottled water (adjusted effects = -14.54 μg/L; 95% CI: -26.06, -3.01; p = 0.013) was associated with lower UIC levels.

Conclusion: This study revealed that WASH-related factors influence UIC levels of Filipino WRA, including improved water access and the method of garbage disposal. Nutritional status, age, ethnicity, household wealth index, dwelling type, occupation, and household salt iodine content were also observed as significant factors. Hence, targeted WASH interventions, alongside salt iodization programs, should be prioritized to comprehensively address iodine deficiency among Filipino WRA.