Global Review of Health Care Surveys Using Lot Quality Assurance Sampling (LQAS), 1984-2004

Abstract in Brief:



This study conducted a comprehensive global review on the use of lot quality assurance sampling (LQAS) surveys to assess aspects of health care including service delivery, health behaviour and disease burden. A total of 805 LQAS surveys were identified between 1984-2004, through a literature search of publications from six electronic databases, the World Health Organisation, the World Bank, governmental and non-governmental organisations, and individual practitioners. Surveys were then classified using a standard form. The 805 LQAS identified here were conducted in 55 countries and measured health care parameters such as: risk factors for sexually transmitted infections (320 surveys); immunisation coverage (266 surveys); post-disaster assessment (240 surveys); women’s health (224 surveys); growth and nutrition (142 surveys); diarrhoeal disease control (136 surveys); and quality management (88 surveys). A greater than 12-fold increase in the annual number of LQAS surveys was seen by the end of 2004. LQAS surveys are found to be a practical field method increasingly applied in the assessment of preventative and curative health services, and can be used to measure variation in behaviour change when collected recurrently at multiple time points.



General Principles of the LQAS Method



The LQAS method was originally developed in the 1920s as a quality control technique for industrially produced goods, but by the 1980s its sampling concepts were recognised as having universal applications. It is grounded in the principle that inspection of a small, representative sample of a lot will allow for the acceptance or rejection of the entire lot with high probability, should the number of defective goods in that sample exceed a predetermined allowable number. In health systems, a lot most often consists of a supervision area (community or health facility catchment area) and the production unit is the set of health workers in that area. The purpose of using LQAS in this setting is to:

1. Determine whether a specific supervision area has reached the predetermined coverage target.
2. Compare the performance of difference supervision areas.

To use LQAS, health system managers need to identify two thresholds. The first is the coverage target, or proportion of the community that health workers ought to reach during a predetermined time period. The second is an unacceptably low level of coverage that should provoke identification of the causes of the failed service delivery and a focused effort to resolve them.



Several characteristics have made LQAS attractive to health system evaluators:

• A small sample is needed to judge whether a supervision area has reached the predetermined coverage target. This means that data collection does not compete with time for provision of health services.
• LQAS sampling procedures and analyses are relatively simple, which is helpful for supervisors and healthworkers who need management tools that can be easily understood and applied.
• The results provide supervisors with a decisive judgement about action based on a predetermined hypothesis.
• LQAS is a valuable tool when a large number of communities need to be tested.
• Data from individual supervision areas can be combined into an estimate of coverage for an entire programme area that includes multiple supervision areas.

LQAS Training Materials



The increasingly widespread usage of LQAS in recent decades generated a need for standardised formats and standardised presentations, and has resulted in the production of a number of LQAS manuals and guidelines targeted at field users. This article documents 12 manuals published from 1991 onwards, on topics ranging from general health monitoring, immunisation, malaria, neonatal tetanus, nutrition, oral rehydration therapy (ORT), trachoma and tuberculosis.

Major Conclusions



Use of the LQAS method in various health sectors has spread worldwide, with greatest uptake in Africa and in the Americas. The majority of the LQAS surveys (92%) have been conducted in lower income or lower-middle income countries. This reflects the increasing demand for data in areas where healthcare infrastructure is gradually being developed and strengthened. The greatest numbers of LQAS surveys have been used to assess risk factors for HIV/AIDS and sexually transmitted infections, although substantial numbers have also been conducted to assess immunisation coverage, growth and nutrition, and post-disaster health status of communities. The LQAS surveying technique can provide insight in these areas into understanding the relationships between various investments in social, human, and physical capital, and into the effectiveness of differing health strategies in achieving behavioural outcomes.