FHI - Accurate Lab Tests

Providing the prompt, accurate diagnostic services so critical to effective health services is a challenge in countries with limited resources. Even in Ghana -- a country with a well-established public laboratory system and well-trained staff -- the accuracy of laboratory test results is not always a given.

Findings from a series of proficiency tests conducted by Ghana's National Public Health and Reference Laboratory (NPHRL) sounded the alarm about the quality of laboratory diagnostic services. "We would send the same sample to two different labs and get two different results," said Veronica Bekoe, NPHRL chief biologist.

These findings suggested that many cases of HIV, sexually transmitted infections (STIs), malaria, meningitis, hepatitis and other diseases were being misdiagnosed.

NPHRL officials suspected that a lack of standardization among the laboratories was at the root of the problem. During supervisory visits, NPHRL representatives had noted that specialists and technicians at all levels of the laboratory system, from the health centers to the district and regional labs, were using different methods and reagents to test for the same disease, with widely differing results.

"We knew that it could be human error that contributed to the high level of inaccuracy, but that it could also be the result of non-standardized testing procedures," said Veronica Bekoe, NPHRL head technologist.

The NPHRL moved quickly to address the problem. From December 1998 to March 1999, with technical assistance from Family Health International's IMPACT Project, its staff developed standardized operating procedures (SOPs) for the most commonly used tests performed in all the country's clinical and public health laboratories. "We decided to address the problem by first developing the SOPs, and then providing training and follow-up," explained Bekoe.

These SOPs will help lab specialists and technicians conduct more accurate tests, contributing to more effective treatment, disease control and surveillance. As a means to achieving more accurate diagnosis of HIV and other STIs and obtaining better information about the spread of these infections, the procedures are an important part of a wider FHI/IMPACT effort to strengthen the National AIDS Control Programme's response to HIV/AIDS through technical assistance to the public health system in laboratory services and STI training, service delivery and evaluation.

The Challenge

Like many other countries around the world, Ghana faces daunting challenges in controlling infectious diseases. HIV prevalence -- though relatively low for sub-Saharan Africa at 4 percent of the adult population -- has reached the critical level at which experts believe HIV/AIDS epidemics can still be contained, but only if they are addressed promptly and effectively. Diseases once thought to be largely under control, such as malaria and tuberculosis (TB), are resurging, and the development of drug-resistant strains of these and other common infectious diseases makes treatment difficult and even more expensive.

Improving the ability of laboratories to provide prompt, accurate information to health care providers and decision makers is one of the cornerstones of the U.S. Agency for International Development's infectious disease control strategy and a critical step in strengthening national responses to HIV/AIDS.

"Laboratory testing is essential to the diagnosis, monitoring, and surveillance of disease, particularly emerging diseases," said Sheila Mitchell, a specialist in laboratory sciences and consultant for FHI/IMPACT. "Clinicians and public health officials rely on accurate laboratory test results for diagnosis and treatment and also for monitoring disease trends and drug resistance."

Other challenges pose a threat to the accuracy of laboratory diagnostics in Ghana, including shortages of supplies and equipment. But standardizing testing procedures is an important first step in improving laboratory services because even slight variations in methodology can affect the accuracy of a test, Mitchell explained.

Such variations include differences in timing and in the dilution of reagents used in certain tests. For example, when using staining methods to detect acid-fast TB bacilli, one lab technician might leave the stain on for five minutes and another for ten. One might mix a 50 percent solution of a required reagent, while another mixed a 75 percent solution.

"It's really like cooking," Mitchell said. "Some people follow the recipe exactly, and some people put in a pinch of this and a pinch of that. But unfortunately, with laboratory diagnosis the consequences of getting it wrong are much more serious."

For TB diagnosis, for example, precise timing and use of the correct reagents are critical to the sensitivity of the test. "Any modification can lead to inaccurate results," Mitchell said.

The Response

A lack of national standards for laboratory procedures is hardly an unusual problem. What is noteworthy is the response of the national laboratory system in Ghana, which has grown over the past 90 years from its humble beginnings as a small laboratory in a classroom to a network of more than 800 laboratories operating in health centers and district, regional, and teaching hospitals.

The NPRHL used a participatory approach to develop the SOPs. In October 1998, Bekoe organized a technical group with representatives from all laboratory disciplines who compiled lists of the tests used at the different levels of laboratories. Then, with technical assistance from FHI/IMPACT, technical group members developed a format for the SOPs and began drafting the procedures.

In December 1998, FHI/IMPACT supported a one-week workshop for 48 lab specialists and technicians from all ten regions in Ghana and the two teaching hospitals to further develop and refine the SOPs. At the end of the workshop, more than 100 SOPs had been drafted and were ready for editing and review.

"This many SOPs could not have been agreed upon and produced in this short time period using any other process," said Mitchell, who worked with the NPHRL to manage the process and edit the manuals. "The participation of lab specialists from all levels of laboratories, different geographic regions and different lab disciplines also will ensure that the SOPs are practical, easy to follow, and will be used in the laboratories."

Each SOP includes a brief explanation of the principle behind the testing method, lists of the reagents and equipment to be used, a step-by-step description of the procedure, and instructions on any special requirements or precautions.

For example, the SOP for a rapid HIV test (performed only at regional hospitals in Ghana), explains the principle behind the HIV Spot Method, a test that uses what is known as a "capture reagent" absorbed on a porous membrane to trap antibodies to HIV-1 and HIV-2. It lists eight detailed steps to follow, beginning with writing the sample number on the testing device, and nine special precautions for performing the test safely and accurately.

The SOPs have been compiled into manuals for each level of laboratory. In addition, 15,000 laminated sheets of the 10 most common procedures have been produced for use by technicians on the bench. "While the manual is an important reference tool, we hope that the laminated sheets will help technicians on a daily basis in their testing of common diseases," said Mitchell.

Mitchell, who was a microbiologist at the U.S. Centers for Disease Control and Prevention for ten years, noted that it is an ambitious objective for laboratories in any country to systematically standardize and document SOPs and to keep them updated.

"Unless they are regulated by law to do so, few laboratories willingly take the initiative to develop and maintain SOPs because of their heavy workloads and competing priorities," said Mitchell. "But the public health laboratory system in Ghana recognizes the importance of high-quality laboratory testing. It has established a model process and product which can, and should, be shared with other resource-poor countries."

-- Paula Stauffer

Paula Stauffer, a specialist in family planning and reproductive health, is the former resident coordinator of the FHI/IMPACT program in Ghana.

Making Lab Tests More Accurate: Ghanaian Effort Offers Model Process