Consultancy Report
To Improve the Quality Control System for Salt Iodine Laboratories In Laos
Dr. Li Sumei
August 1- August 4, 2005

Missions

As a short-term consultant, the author was invited to make a visit to Laos between 1 and 4 August 2005. The missions were as follows:

•  To assess the current quality control system both in salt production level and health sectors

•  To assist in developing a quality assurance program for salt iodine testing based on the existing guideline on monitoring supply of iodized salt in Laos

•  To assist the consultant who comes from China salt to improve the use of WYD checkers

Main Activities

In collaboration with UNICEF, FDQCC and FDD department, the following activities were conducted in 4-day visit:

•  Understand the overall situation of salt monitoring and laboratory testing system by document review and discussion with FDQCC and FDD and salt sector.

•  Visit Khoksaath and Veunkham salt factories in Vientiane municipality and Vientiane city IDD laboratory, as well as the central salt iodine and urinary iodine laboratory. Field observation in the laboratories and interview the technical staff related quality control and the problems in WYD performances.

•  Introduce Chinese national quality assurance system and provide a short training course on testing quality control to the laboratory technicians coming from 7 salt factories and 7 provincial laboratories

•  Help Mr. Zhao Yi who comes from China Salt to check WYD machines and teach how to use the WYD in a correct way, and also to be Chinese-English translator in the whole visit.

Document Review

USI, which initiated in 1995, was implemented as the most appropriate and sustainable strategy to eliminate IDD in Laos. Salt idolization standard was more than 30ppm at the production level, and more than 15ppm at the consumer level. In 2004, salt idolization standard increased to 40-60ppm and more than 20ppm at production and consumer level respectively for the iodine loss in salt delivery and storage.

Total salt requirement in Laos is 28,000 tones/year (5kg/person/year + 2,000 tone for commercial requirement). 90% of total iodized salt produced by 7 salt factories, 5% came from small-scale and 5% imported from neighboring countries.

Salt monitoring system has been established since 2004, the monitoring guideline mainly focused on the 7 large salt producers, as this will capture a significant proportion of the total salt supply. In addition, a school-based monitoring was developed to understand the iodized salt coverage at the households level, and identified the possible problems and its resources, including the salt from 7 salt factories, small producers and neighboring countries.

Salt iodine testing was conducted daily in 7 salt factory laboratories, and 7 provincial laboratories check the testing quality to salt factories once per month; the national laboratory is responsible for training staff from above laboratories, preparing and providing the key reagents that the lower level laboratories can not prepare for provincial and salt laboratories.

1. The overall situation of the current quality control system according to the guideline

The current quality control system includes internal quality control conducted by the salt factories themselves and supervising quality verification by provincial laboratories in the production level.

•  Internal quality control within in the salt factories

•  Hourly testing of iodine in salt has been done by using a rapid test kit (RTK) to determine if there is iodine present in salt. RTK are only qualitative measures that can distinguish between the presence and absence of iodine.

•  Each day, 15 salt samples are selected at random at three times during the iodization process: 5 samples when the process of iodization begins, 5 samples in the middle of the iodization process, 5 samples at the completion of iodization. It is recommended that the 5 salt samples taken at each point in time be from different locations following iodization, including the mixing drums and the point where the salt is emptied into bags. Analysis of the iodine content was conducted on each sample using the WYD kits.

•  The supervising quality verification

The monthly supervising quality verification of production level quality control has been done to test the adequacy of iodized salt being produced as well as to verify the accuracy of records maintained by the factories. The Inspectors who come from provincial laboratories work together with the Factory QA Technician in the factory to collect 15 salt samples, selecting these at random but only at one time during the day, preferably near the end of the iodization process. These 15 samples are separated into two equal amounts and labeled, i.e. one set for the factory to test and a second set for the Provincial FDD Inspector to test. Analysis of the iodine content of the first 5 samples are conducted together with the Inspector observing the technique and methods used by the QA Technician from the factory. The remaining 10 samples are analyzed independently by the Factory QA Technician at the factory and recorded in the daily logbook and then the results for all 15 samples are sent to the Provincial lab. The 15 samples which are collected at the factory by the Inspector and are analyzed using the WYD kit after returning to the Provincial lab. The results from the two sets of analysis should be compared at the end of the month.

Where the difference between the Factory Results and the Inspector Results are significant after the 15 samples are analyzed, there will need to be follow-up action.

2. The questions raised from the current quality control system according to the document review

•  The current internal quality control which mentioned in the guideline is to ensure the salt factories to produce adequacy iodized salt by using routine salt iodine testing, however, who will be responsible for the assurance of testing itself?

•  Monthly verification was conducted by collecting 15 samples, which are tested in both provincial laboratories and salt factory laboratories, if there is significant difference between the results of the two laboratories, which one is correct? How can the laboratory prove their results are correct? Even the results of the two laboratories are close, Can we say they are all correct?

It is clearly that the concept and the content of the quality control in the guideline is for salt monitoring not for salt iodine testing, salt monitoring is based on the prerequisite that the salt iodine testing is accuracy, it is necessary to provide evidence to prove the testing is actually accuracy. To answer the above questions, a testing quality control system should be established in Laos, it will be the important supplementary to the current guideline.

Field observation and interview

In the two salt factory laboratories and one provincial laboratory, the technicians conducted the performance of WYD calibration and salt iodine testing, the investigators interviewed the laboratory staff related to quality control and the existing problems during the use of WYD checker, and the record logs were checked.

The findings from filed observation and interview are as follows:

•  The laboratories implemented sample collection, testing and result record according to the guideline, the monthly summary are reported timely and clearly. The technicians know how to calculate Mean, SD and CV.

•  The technicians of all three labs claimed that they had been trained by the national or provincial laboratories in testing salt iodine with WYD checker.

•  There are necessary resources for salt iodine testing in the three laboratories, including WYD checker, distilled water, standard solution which provided by the national laboratory and other consumption materials.

•  But, the technicians lack the knowledge of internal and external quality control for testing; they do not completely know how to calibrate WYD checker and gray grass ( a standard reference for spectrometry); their testing performances are not so skilled, for example weighing salt samples and pipette solutions; they also have little knowledge about maintenance of WYD checker by clearing the testing cell during and after testing, and keep the gray grass in a clear condition.

•  All the laboratories do not have internal quality control samples; therefore, they never use any internal QC sample to control the testing quality of salt iodine.

•  The national laboratory never conducted external quality control to provincial and salt factory laboratories by using blind QC samples or reference materials.

The gaps of the current quality control system

According to the related document review and field visit, a salt monitoring system has been established in Laos, the guideline is an important document to guide health sector and salt sector to conduct salt monitoring in production level. However, there are some gaps in the current quality control system:

•  The system lacks quality control for salt iodine testing including internal quality control in all the laboratories and external quality control that the national laboratory should conduct to the provincial laboratories and salt factory laboratories.

•  Technical training to the laboratory staff is not adequacy according to the field observation.

•  The current roles of the national laboratory are weak in quality control and technical support. It is necessary to develop its functions in the quality control system.

Recommendations for quality control strategies of salt iodine testing

•  To establish internal quality control within all the testing laboratory

Internal quality control is the strategy of self-control by the testing laboratory, it is important for ensuring testing quality and building up self-confidence of laboratory staff, it is also the basis and prerequisite of conducting external quality control.

In order to conduct internal quality control, quality control samples must be prepared and provided to the provincial and salt factory laboratories first. With the quality control samples, every laboratory should conduct quality control activities according to appendix 1.

To prepare quality control samples is not easy for the national laboratory, because the domestic salt is not suitable for preparing QC samples for inadequacy purity, too much moisture and bigger grains, these characters can lead to iodine loss, therefore, the QC samples will be not stable and reliable. The national laboratory need to acquire purified non-iodine salt, as well as some necessary equipment such as dry machine, mixing machine and packing machine. In addition, the national laboratory needs much training for preparing QC samples.

•  To establish external quality control to all the testing laboratories

External quality control is the external supervision to the testing laboratories, it is usually organized by higher level laboratory to ensure the testing quality of a group of laboratories, identify the system error existing in individual laboratory, and increase the comparability of the results coming from different laboratories.

Proficiency testing is a kind of special external quality control; the differences are the testing being organized by a reference laboratory in which the testing accuracy can be traced to national or international metrological standards, and the reference materials are used to be the blind QC samples.

To conduct external quality control, the national laboratory should prepare quality control samples, or buy reference materials from China, and keep the values of the QC samples or reference materials in confidential, mark them with numbers instead. Then the activities need to be conducted according to appendix 2

3.Strengthen staff technical training to national laboratory

The national laboratory play an important role in the quality control system in Laos, to improve the capability through training is necessary. the national laboratory need to be trained in following aspects:

•  Knowledge of internal quality control and its implementation

•  Organization and implementation of external quality control; evaluation and dissemination of the results.

•  Preparation of standard solution and solution A and B for provincial and salt factory laboratories

•  Preparation the quality control samples

•  Training skills

4.Strengthen staff technical training to the provincial and salt factory laboratories through the national laboratory

It is necessary to keep on-going training course for the provincial and salt factory laboratories by regular workshops in which the new staff will be trained and all the technicians will have the opportunity to exchange their experiences in testing; The national laboratory will discuss with the lower level laboratories related to the problems found in the testing and research the measures to solve the problems and improve the testing capability.

5. Participant regional proficiency testing

To participant regional proficiency testing conducted by China national reference laboratory, which is also the regional resource laboratory is necessary for increasing testing capacity. The proficiency testing is usually conducted once a year.

Recommended Following Actions For Next Step

•  Quality control manual

As a supplementary of the current guideline, a quality control manual for salt iodine is important to establish a quality control system in Laos. FDQCC should draft the manual ccording to the appendix 1 and 2.

•  Oversea training for the national laboratory staff.

The national laboratory staff need to be trained outside in order to develop its function. China National Reference Laboratory is recommended an experienced laboratory for oversea training. It is not only because this laboratory is also Asia-western pacific regional resource laboratory, but also there is an on-going quality assurance network in China and can share experiences with other countries with similar conditions of IDD elimination program.

3. Initiate quality control program for salt iodine testing

In order to establish a quality control system, quality control samples are necessity. The national laboratory of Laos will have the capacity to produce quality control samples in future through training, but as a initiation of the quality control system in Laos, to purchase reference materials of salt iodine from China is the better choice and the easier strategy, in this way, the testing quality control system can be established earlier to support IDD elimination program.

Appendix 1

Internal Quality Control Guideline For Salt Iodine Testing

Internal quality control is the strategy of self-control by the testing laboratory, it is important for ensuring testing quality and building up self-confidence of laboratory staff, it is also the basis and prerequisite of conducting external quality control.

In order to conduct internal quality control, quality control samples must be prepared and provided to the provincial and salt factory laboratories first. With the quality control samples, every laboratory should conduct quality control activities according to the following requirements:

(1) Salt factory laboratories should test the quality control samples while they are doing the salt sample testing. They conduct 3 lots testing everyday according to the guideline, 5 samples in each lot. There are two recommendations for the laboratories to choose, one is the completed QC method , another is the simplified QC method (appendix 1) . The completed QC method is recommended in the initiated period of QC program, the simplified QC method is recommended in the stable period of the quality control program and the on-going quality control work.

The completed QC method:

When they test each lot of salt samples ( 5 salt samples), they should test 2 quality control samples (one is higher concentration, another is lower concentration) simultaneously. Totally 6 QC samples will be tested each day, 2 at the beginning of the iodization, 2 at the middle and 2 at completion of iodization. After finishing one lot testing, The laboratory staff should make self-assessment for the quality of THIS LOT according to the following rules:

•  If the results of 2 QC samples in this lot are all within the reference range, the results of THIS LOT salt samples are acceptable

•  If the results of 2 QC samples in this lot are all out of the reference range, the results of THIS LOT salt samples are refused, and the laboratory staff should check the whole testing process to identify the possible problem and take corrective measures, then the salt sample should be retested

•  If one QC sample is within the reference range, but another is out of the reference range, the laboratory staff should retest the out-range QC sample.

•  if the retest result is within the reference range, the results of THIS LOT salt samples can be acceptable;

•  If it is still out of the range, to open and test another package of QC sample with the same iodine concentration is strongly recommended. If the result of new QC sample is within the reference range, the results of THIS LOT salt samples are acceptable. If the result of new QC sample is still out of the reference range, the results of THIS LOT salt samples are refused, the laboratory staff should check the whole testing process to identify the possible problem and take corrective measures, then the salt sample should be retested.

The simplified QC method :

Salt factory laboratories need not to test 2 QC samples in every lot testing when the testing quality is showed stable in their routine work. What they need to do is testing 2 QC samples only at the beginning of the iodization while the first 5 salt samples are testing. Then they make self-assessment to the testing quality of the whole day ( 3 lots, totally 15 salt samples) according to the following rules.

•  If the results of 2 QC samples are all within the reference range, the results of the 3 LOTS salt samples are acceptable

•  If the results of 2 QC samples are all out of the reference range, the results of 3 LOTS salt samples are refused, and the laboratory staff should check the whole testing process to identify the possible problem and take corrective measures, then the salt sample should be retested

•  If one QC sample is within the reference range, but another is out of the reference range, the laboratory staff should retest the out-range QC sample.

•  If the retest result is within the reference range, the results of THIS LOT salt samples can be acceptable; BUT the laboratory staff need to change the QC strategy form The simplified QC method to The completed QC method in the rest of the testing of this day. In other words, they need test 2 QC samples while they are testing the salt samples at middle of iodization and 2 QC samples while they are testing the salt samples at completion of the iodization respectively in the same day;

•  If the retest QC sample is still out of the range, the results of THIS LOT salt samples are refused, the laboratory staff should check the whole testing process to identify the possible problem and take corrective measures, then the salt sample should be retested

(2) The provincial laboratories conduct supervising quality monitoring once per month in the salt factories according to the guideline. They collect 15 samples and test them in the provincial laboratories. When they test 15 salt samples, they should test 2 quality control samples (one is higher concentration, another is lower concentration) simultaneously. The rules of the self-assessment is the same with The simplified QC method .

(3) Every laboratory should record the daily QC results in the internal quality control chart ( as showed bellow), the chart can provide a clear view of monthly testing quality, and most important is that the chart can help laboratory staff to predict the trend of the testing quality. If the flotation of the QC results around the Mean becomes bigger gradually, it reminds laboratory staff to check the potential problems before the testing out of control.

* the mean of the QC sample is 51mg/kg, Reference range is 51±2mg/kg
(4) The internal quality control results should be recorded in daily logbook.

Appendix 2

External Quality Control Guideline For Salt Iodine Testing

External quality control is the external supervision to the testing laboratories, it is usually organized by higher level laboratory to ensure the testing quality of a group of laboratories, identify the system error existing in individual laboratory, and increase the comparability of the results coming from different laboratories.

•  The national laboratory delivers the blind QC samples (2 concentrations) to the provincial and salt factory laboratories, and provide related information about the QC sample and testing, such as the notice of using the QC samples, the requirements of testing time and testing frequency, the report deadline and report form, et al.

(2) The provincial and salt factory laboratories should test the external QC according to the requirements and report the testing result to the national laboratory before the deadline.

(3) The national laboratory evaluates the result coming from the provincial and salt factory laboratories according to the following rules

•  If the results of 2 QC samples are all within the reference range, the testing ability of the laboratory is qualified.

•  If one of the 2 QC samples is out of the reference range, or 2 QC samples are all out of the reference range, the testing ability of the laboratory is unqualified.

(4) The national laboratory feedback the results to the provincial and salt factory laboratories. The unqualified laboratory should check the whole testing process to identify the possible problem and take corrective measures. The national laboratory should provide technical support to the unqualified laboratory. After the mistakes are corrected, the laboratory can ask for another lot of blind QC samples from the national laboratory if both sides think it is necessary.