Data Notes
Monitoring the elimination of iodine deficiency disorders
A set of guidelines for monitoring IDD control programs with process and impact indicators are described in the World Health Organization (WHO) manual, Assessment of iodine deficiency disorders and monitoring of their elimination. In terms of process, it is important to monitor the iodine content of salt at the production/import, retail/wholesale and household levels (consider also assessing usage iodized salt in the food industry, where applicable). To monitor impact, median urine iodine concentration is the primary indicator for assessing the iodine status of a population, with total goiter prevalence providing useful additional information. WHO maintains a program impact database with indicators related to the prevalence of urinary iodine and goiter.(1) UNICEF maintains a database on household consumption of iodized salt. Currently, no agency is responsible for reporting other process-related indicators regarding production, import or sales. Ideally, all process indicators should be combined with impact data to best guide programs and policies in each country.
The indicator
The indicator presented on this page, “Percentage of households consuming iodized salt,” gives part of the picture when it comes to tracking TID elimination efforts.
| Indicator name | Definition | |
|---|---|---|
| Numerator | Denominator | |
| Percentage of households consuming iodized salt (>0 ppm) | Number of households surveyed that used salt for cooking and tested positive (> 0 ppm) for the presence of iodine. | Number of households surveyed |
| Percentage of households consuming iodized salt (>0 ppm) among all tested households with salt | Number of households surveyed that used salt for cooking that tested positive (> 0 ppm) for the presence of iodine. | Number of households surveyed that had salt |
The latest monitoring manual suggests a minimum of 15 parts per million (ppm) of iodine in salt. It is important to assess the amount of iodine in salt samples: to be fully effective in correcting iodine deficiency, iodine-containing salt must not only reach the entire affected population, but it should also contain enough (but not too much) iodine. Although some countries may have different targets (e.g. 12 ppm), the WHO recommendation is to have a concentration of 15 to 40 ppm of iodine in salt at the household level. However, assessment of iodine in salt through household surveys has generally been achieved through the use of rapid test kits. Still, the WHO recommends using only rapid test kits to indicate the presence of iodine and using quantitative methods (e.g., titration) to quantify and report the iodine content of salt. Currently, very few countries have quantitative estimates of iodized salt based on recommended methods, but as the availability of these data increases, the database can be updated to also include related estimates to the iodine content of the salt.
Assessment of iodine content has generally been carried out through the use of rapid test kits. Although the test kit cannot provide data as precise and accurate as titration, it remains the testing method associated with most data points in the global database. Based on WHO recommendations to use only rapid test kits to indicate the presence of iodine and to use another method – titration – to quantify and report the presence of salt containing a particular amount of iodine , a number of countries have stopped reporting the reduction. of ≥15 ppm and only report iodine-containing salt (>0 ppm) in many recent surveys.
Note: The indicator shown on the first map on this page is “percentage of households consuming iodized salt”, while estimates for a similar but different indicator of “percentage of households with salt that consumed iodized salt” are available in there downloadable datasets.
Data collection and reporting
Data on household consumption of iodized salt are collected primarily through nationally representative household surveys, such as MICS and DHS. A more limited number of national estimates in the global database come from primary school surveys in countries where the net primary enrollment rate exceeded 90 percent at the time of the survey or also from reporting systems. monitoring.
Boundaries
There are various limitations associated with reporting progress in household consumption of adequately iodized salt, many of which relate to advances in methodologies and maturation of programs. Great progress has been made in improving program monitoring, leading to increased availability and improved quality of data over the past decade. At the same time, they make older data non-comparable to newer data, thereby limiting the ability to undertake trend analyses. Some key issues are highlighted below:
Moving from monitoring production to household consumption
- Questions on household consumption of iodized salt were not added to large household surveys until the mid-1990s. Even then, not all countries had estimates based on iodized salt. household data. In the early to mid-1990s, many national estimates presented in UNICEF’s annual report The situation of children in the world were based on extrapolations from iodized salt production figures. Since these estimates are not comparable to current data based on household consumption, they cannot be used for trend analysis.
Testing for iodine in household salt samples
- Self-declaration: Although the move from production-based estimates to household consumption-based estimates was positive, it nevertheless introduced some bias since the first estimates were often based on self-reported information. Even some early EDSs did not test for iodine in household salt, relying on self-reports by the respondent or cross-checking against the salt’s label/brand name by the investigator. These self-reported estimates are not comparable to current data based on household consumption which require salt to be tested for the presence of iodine and therefore cannot be used for trend analyses.
- Rapid test kits for the presence of iodine: These kits allow salt to be tested for the presence of iodine and were introduced into many surveys in the mid to late 1990s as a means of cross-checking a salt sample within the household during the survey. This helped reduce the bias of estimates based on self-report from household survey data and represents one of the first examples of direct testing in household surveys. Currently, almost all MICS and DHS as well as most other national household survey and monitoring mechanisms include a salt testing component using rapid iodine test kits.
- Quantitative tests for iodine: The most recent WHO recommendation is to use quantitative methods such as titration to quantify the iodine content of salt samples collected during household surveys. These recommendations also call for the use of rapid test kits to indicate only the presence of iodine. Since the use of quantitative methods to assess iodine content is far from universal and many countries only report iodine-containing salt based on rapid test kits, it has not been possible to report sufficiently iodized salt in the global database. date
