predicting mortality in COPD patient

Hello fellow nurses,

My question is on the prognosis of COPD. I was wondering if someone would be able to extrapolate on the assessment of the QMVC, and muscle endurance in relation to the prediction of mortality. I heard that quadriceps dysfunction can be present for COPD patients who are NOT exhibiting respiratory difficulty, low weight, and other co-morbidities.

Any feed back would be great!