The effect of protein supplementation on quality of life, physical function, and muscle strength in patients with chronic obstructive pulmonary disease

BACKGROUND: The combination of protein supplementation with exercise is successful in increasing weight and energy intake, as well as exercise capacity and health--related quality of life in sarcopenic patients diagnosed with chronic obstructive disease (COPD). However, the potential benefit of protein supplementation for non--sarcopenic patients with COPD has yet not previously been examined.

AIM: The aim of this trial was to evaluate the effect of protein supplementation on quality of life, physical function, muscle strength and biochemical blood markers in patients diagnosed with COPD undergoing nine weeks of pulmonary rehabilitation.

DESIGN: A prospective, parallel group randomised clinical trial. Setting: Patients referred from their general practitioners to the COPD rehabilitation outpatient programme at the local community rehabilitation centre.

POPULATION: Patients (n=53) with stable moderate to severe COPD diagnosed with COPD, 40 years or older and with a BMI < 30. Methods: The participants were assigned to one of two groups to receive either twice daily protein supplementation (9,3g of protein/566,4KJ) plus exercise or exercise only. Before and after nine weeks of rehabilitation, mental state was measured by means of St George Respiratory Questionnaire, physical performance was evaluated by shuttle walking test and maximal muscle strength test, and fasting blood samples were analysed.

RESULTS: Supplementing exercise with protein had no additional effect on any of the outcome measures. However, shuttle walk time, St George total score and subscore for impact improved as effect of time.

CONCLUSION: This trial was unable to provide evidence for the effect of protein supplementation on quality of life, physical function, and muscle strength in non--sarcopenic patients with moderate to severe COPD.

CLINICAL REHABILITATION IMPACT: The role of protein supplementation in COPD--rehabilitation should focus on identifying patients to receive supplement with protein and from those who will not benefit.