COPD, a chronic and progressive disease that affects respiratory function in patients, is a complex health issue to handle. In particular, even the prognosis of COPD is difficult due to multiple contributing factors. This is reflected in the compilation of the BODE index, which is a prognostic tool taking into account body mass index, airflow obstruction, dyspnea and exercise capacity. COPD patients tend to experience degradation in all of the aforementioned areas as their condition worsens. Because muscle weakness, dysfunction and muscle mass loss are associated with reduced exercise performance and quality of life, as well as with increased dyspnea, the muscle strength status of particular patients might be able to predict mortality in COPD patients.

Let’s take a look at a survey that tests the suitability of quadriceps strength as a prognostic factor for mortality in COPD patients.

Key Findings

• Prognosis of COPD is difficult due to the complexity of contributing factors.
• Muscle weakness progresses due to and further contributes to exercise intolerance.
• Quadriceps strength was measured in COPD patients over several years.
• Transplantation-free survival is reduced in COPD patients with reduced quadriceps strength.
• Transplantation-free survival is not affected by COPD severity.

Patient Impact

Reduced quadriceps strength is a predictor of increased mortality risk in COPD patients.

Study Methods

Quadriceps maximal voluntary contraction force (QMVC) was measured in patients in which quadriceps strength had been measured in the preceding five years. Primary endpoints studied were death or lung transplantation (as confirmed by primary care physician).

Study Results

Transplantation-free survival (TFS) is significantly reduced in COPD patients with reduced quadriceps strength. TFS is not affected by the severity of COPD according to GOLD levels.

Quadriceps strength is a strong predictor of mortality. Reduced quadriceps strength/increased quadriceps muscle weakness is highly correlated with increased risk of mortality.

References

Swallow EB et al. Quadriceps strength predicts mortality in patients with moderate to severe chronic obstructive pulmonary disease. Thorax. 2007 Feb; 62(2): 115–120.