Predictive equation for six-minute walk test in Indian children, adolescents, and adults

Post-COVID residual dysfunction has been observed in a majority of people, with reduction in cardiopulmonary endurance emerging as a primary symptom. The Six-Minute Walk Test is a simple, reliable, and valid test that is used routinely on people with chronic respiratory dysfunction. In the current COVID-19 pandemic situation, reference values and a predictive equation developed from a large sample across a large age group, from 6 to 75 years, will enable one to establish goals of treatment for post-COVID rehabilitation.

Following institutional ethical clearance, we recruited 1369 participants for the study (685 females and 684 males). Participants were classified according to biological age into group 1 (6-12 years), group 2 (13-17 years), group 3 (18-40 years), group 4 (41-65 years), and group 5 (>65 years). Informed consent was sought and participants were screened using a health history questionnaire. Demographic features, namely, age, height, weight, and body mass index (BMI) were noted. The Six-Minute Walk Test was administered as per ATS guidelines. Clinical parameters, namely, pulse rate, respiratory rate, systolic blood pressure, diastolic blood pressure, and rate of perceived exertion were recorded.

The Six-Minute Walk Test (6MWT) was significantly influenced by age and gender (r = 0.257, P = 0.00 and r = 0.501, P = 0.00, respectively). Walking distance was longest in 13-17-year-old males, whereas females demonstrated a linear decline after 12 years. In each age group, males walked a greater distance than females. Stepwise linear regression analysis was used to derive the following predictive equation: 6MWT = 491.93 - (2.148 × age) + (107.07 × gender) (females = 0, males = 1).

The study confirmed variability of the Six-Minute Walk Test, with age and gender being predominant predictors. Reference values, equations, and percentile charts generated from the study can be utilised to guide clinical decision-making while exercise prescription for patients with post COVID dysfunction.