Universal salt iodization contributes to health equity: socio-economic status does not affect iodine status in children in Macedonia

Many studies have shown that socio-economic status (SES) contributes to health inequalities, with nutrition as one of the major risk factors. Iodine intake entirely depends on external sources, and deficiencies are known to be more prevalent in lower social groups, especially in countries with limited access to iodized salt. This study aimed to determine the influence of SES on iodine status and iodine availability from household salt in North Macedonia. Using cluster sampling, 1,200 children were recruited, and 1,191 children participated (response rate: 99.2%). Iodine status was assessed through urinary iodine concentration (UIC), and iodine availability through iodine content in household salt requested from participants. SES was assessed using standardized Family Affluence Score (FAS). No statistically significant correlation was found between FAS and iodine in salt. Median regression revealed no significant associations of middle vs. low FAS ({beta}=0.00; 95%-confidence interval (CI)=[-0.61, 0.62]; p=0.999) or high vs. low affluence ({beta}=0.48; 95%CI=[-1.37, 0.41]; p=0.291) with iodine content in household salt. UIC levels were significantly lower in middle FAS children compared to low FAS children ({beta}=-16.4; 95%CI=[-32.3,-0.5]; p=0.043). No statistically significant differences in UIC were found between children with high and low affluence ({beta}=-12.5; 95%CI=[-35.5, 10.5]; p=0.287), possibly due to lowered statistical power for this comparison. Universal salt iodization (USI) proves to be cost-effective measure for appropriate iodine intake in healthy children and adults, irrespective of their social status. It can thus be concluded that USI contributes to reducing health inequalities related to iodine status among population of different social strata.