Table 2.

Medical Research Council (MRC) average score in estimated severity in groups of COPD^∗ (N = 1,499).

Estimated severity of COPD	Mean	SD
No obstruction	1.47	0.68
Mild COPD	1.39	0.66
Moderate COPD	1.76	0.84
Severe COPD	2.25	1.09
Very severe COPD	3.00	1.35

^∗Chi-square 88.8; P < 0.001.