Developing standard reference data for Thai children from a six-minute walk test.

Background: The six-minute walk test (6MWT) is a useful test for pre-and post-treatment comparisons, measuring functional status and predicting morbidity and mortality. The test is not widely used with children because the exact reference data in healthy children are often not known and the test requires concentration and co-operation from the participants, which is harder to manage in children. Data for children have been studied in many countries, but data for Thai children is limited.

Objective: To establish reference values for a six-minute walking distance (6MWD) of healthy Thai children aged between 9 and 12 years.

Material And Method: A cross-sectional study was conducted in healthy children attending the 4 to 6 grades of seven primary schools in Songkla province in southern Thailand. The tests were conducted according to the American Thoracic Society (ATS) guidelines between June and September 2008. The potential variables were evaluated for their relations and confounding factors. Reference curves were developed.

Results: Seven hundred thirty nine students were recruited for the study, 403 boys (54.5%) and 336 girls (45.5%). Only one girl could not complete the test. The mean 6MWD was 677 (+/- 62.2) meters. The average walking distance was 36.4 meters greater in boys than girls (693.5 and 657.1 meters, respectively). The walking distance increased with age from 9 to 12 years of age in boys, but it decreased with age in girls after 11 years old. There were no unexpected events during or after the tests. Multivariate analysis showed that the 6MWD correlated to age, sex, weight and heart rate differences. Age-specific centile curves of 9 to 12 years for the 6MWD in each sex were developed.

Conclusion: 6MWT a practical simple test, is one of several modalities for objective evaluation of functional exercise capacity. The reference value of 6MWT for healthy Thai children aged 9 to 12 years was calculated and reported.