Reference values of 6 minutes walk test (6 MWT) in Bangladeshi healthy subjects aged 25-55 years

Abstract

Introduction: The six minute walk test (6MWT) is increasingly accepted worldwide to assess functional exercise capacity of cardiac and pulmonary diseases for its simplicity.Aims and objectives: The aim of the present study was to provide reference values for 6 Minute Walk Distance (6MWD) and other primary variables such as oxygen saturation (SaO2), pulse rate (PR) and breathlessness perception done in 6MWT.Methods: We studied a sample of 190 healthy subjects (53 females) of age between 25-55 years (37.9±8.5 years). Baseline lung functions including forced expiratory volume in 1st second (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio were measured by a flow sensing spirometer. All subjects performed 6MWT according to standard protocol provided by the American Thoracic Society (ATS) guidelines. The fatigue and dyspnoea was measured before and after 6MWT by modified Borg scale. The SaO2 and PR were measured also by a light weight pulse oxymeter. Results: The mean 6MWD was 466.7±69.4 meter, ranging from 213 to 659 meter and the mean Distance Work (DW) was 28732±7024 kg-m. Dyspnoea status and oxygen saturation remained unaltered throughout the walk. Mean resting and walking SaO2 values were, respectively, 97.1±1.3% and 96.8±1.5%. The mean change in SaO2 was 3±1.5%. PR was significantly affected by the walk. Mean resting and maximum PR after walking were respectively, 80±7 and 103±12 bpm (p<.01). Gender significantly affected the 6MWD (p<.01). In all subjects, the 6MWD was inversely and directly related, respectively, to age (r=-.15; P<.05) and height (r=.41; P<.01).Conclusion: This study showed reference values for the 6MWT variables of subjects in Bangladeshi population.Bangladesh Med Res Counc Bull 2014; 40 (2): 70-73

6 Minute Walk Test (6MWT) for Healthy Adult Volunteers

“…Another study focused on 6MWD reference values in healthy subjects ages 25 to 55 years having Bangladeshi origin. 9 The mean 6MWD for their study was 466.7 ±69 m with 36 meters more distance covered compared with our study. Shrestha SK 10 conducted a similar study in Nepal showed mean 6MWT values 489±86 m and 509±82 m for males and 445±78 m for females.…”

“…A negative correlation was noted with age, weight, height, and BMI, and these results were aligned to the data studied from different countries. [7][8][9] The next step for our study was to derive the reference value for the local population that will be a barometer for comparing with other country's reference values.…”

“…There is a significant error and moderate overestimation of 6MWD values among Pakistani populations analyzed comparatively through the 6MWT predictive equation with six widely accepted equations. [4][5][6][7][8][9][10][11][12] There could be several possible explanations for these discrepancies. For example, in terms of testing strategy, the length of the walking course i.e.…”

“…Although ATS recommends a 30 m walking course 1 , different researchers have employed distances ranging from 15 m to 50 m. [4][5][6][7][8][9][10][11][12] A mean between 0-17 percent was observed from data published in the ATS review. 1 Our test subjects were naïve and practice sessions were not allowed, which could have impacted our 6MWT values.…”

“…6 Differences in the covered distance by healthy subjects have been recorded in some studies. [4][5][6][7][8][9][10][11] Results may also be influenced by the variations in study populations and methodology. Furthermore, high variability in predictive power in most of the published predictive equations has been observed suggesting other factors (not considered in the performance test) potentially playing an important role in distance covered.…”