Operational conditions influencing the proficiency of AFB microscopy services in the Philippines

The microscopy services of the Philippine National Tuberculosis Programme (NTP).

To investigate how operational conditions in field microscopy centres (MC) affect proficiency.

In 2004, a newly developed external quality assessment system (blinded rechecking) for acid-fast bacilli (AFB) microscopy employing lot quality assurance sampling (LQAS) was introduced into the NTP by the Philippine government. Performance reported by the quality assurance centres (QACs) of the four provinces and four cities was analysed.

There was no significant difference in rechecking results between small MCs examining fewer than 166 slides (500 slides/3 sputum samples per suspect) and larger MCs in the provinces. City MCs recorded better performance than those of the provinces. A city QAC covers only five MCs in average, whereas a provincial QAC covers 38. The average distance between city QACs and MCs is much shorter (3.2 km) than in the provinces (60.5 km).

The number of MCs to be covered by each QAC and the distances between QAC and MCs are the dominant factors influencing the quality of AFB microscopy. Combining a few neighbouring MCs to reduce the number of MCs and/or provision of sufficient travel funds and timely use of vehicles, particularly in the provinces, are recommended.