Rationale: There is little data available on normative values or prediction equations for entry-level 6-minute walk test (6MW) performance in participants of pulmonary rehabilitation (PR) programs. Having prediction equations for men and women would be valuable for estimating a baseline level of physical performance prior to PR entry.
Objective: To develop valid prediction equations from a statewide registry for entry-level 6MW performance in men and women of North Carolina PR programs.
Methods: Six-minute walk test scores (feet) from 742 men aged 22-90 (mean age = 69 +/- 9.5) (mean +/- standard deviation) and 1,064 women aged 20-93 (mean age = 66 +/- 11.2) with obstructive and restrictive lung diseases from 19 North Carolina hospital-based PR programs were submitted over a 6-year period, via Internet, to the North Carolina Pulmonary Rehabilitation Outcomes Registry. Of this sample, 91% were Caucasian, 8% were African American, and 1% were Hispanic American. The mean forced vital capacity (FVC) values for men and women were 2.33 +/- 1.0 and 1.76 +/- 0.69 L, respectively. The forced expiratory volume (FEV1.0) values were 1.28 +/- 0.68 and 1.07 +/- 0.53 L, respectively. Most participants had emphysema, asthma, and/or chronic bronchitis, while less than 10% had restrictive lung diseases. For this model, a regression equation using age, height, and weight as coefficients and PR entry-level 6MW distance as the dependent variable was employed.
Results: The 6MW prediction equations for men and women are presented below:
These equations expectedly predicted 6MW performance levels lower than did validated equations for apparently healthy or older men and women and for certain cardiac populations.
Conclusions: Having valid 6MW prediction equations for those with chronic lung disease may be useful for the PR practitioner in developing a normative benchmark measure of how far a participant should be able to walk prior to entry into a PR program. Using prediction equations from other populations overpredicts 6MW performance in PR participants. Future investigations should focus on specific prediction equations for those with obstructive, restrictive, and combined lung diseases.