Muscular Strength, Exercise Capacity and Body Composition of Alpha-1 Antitrypsin Deficient COPD Patients

Abstract

PURPOSE: Alpha-1 antitrypsin deficiency (AATD) is the most common genetic disorder affecting people of European descent. The condition often results in the development of emphysema, leading to chronic obstructive pulmonary disease (COPD) in the third/fourth decade of life. Breathlessness, resultant deconditioning and exercise intolerance are often the most troublesome symptoms reported by patients with COPD and are linked to poor quality of life (QoL). Typically, patients with AATD COPD are assessed by pulmonary function test (PFT). However, exercise capacity (EC) cannot be reliably predicted from PFTs. Deconditioning is associated with reduced EC and QoL. The current study examines differences in PFTs, body composition, muscular strength, EC and QoL between AATD COPD patients (ZZ) and alpha-1 antitrypsin replete COPD patients (MM). METHODS: 29 ZZ patients, (m/f 20/9, age 60±yr8, FEV1/FVC: 0.47±0.12, FEV1%pred. 51±22, DLCO%pred. 73±21) were recruited from the National Centre of Expertise for AATD in Beaumont Hospital, Ireland. Patients performed spirometry and diffusing capacity for carbon monoxide (DLCO) was assessed. Body mass index (BMI) and waist:hip (W:H) ratio were calculated. QoL and symptom perception were examined using the SF-36 questionnaire (SF-36) and St. George’s Respiratory Questionnaire (SGRQ), respectively. EC was assessed via 6 minute walk test (6MWT), upper body strength via handgrip dynamometer (HG) and lower body strength via 30 sec sit to stand test (30STS). 9 MM patients (m/f 2/7, age 65±5yr, FEV1/FVC: 0.47±0.15, FEV1%pred. 58±29, DLCO%pred. 72±17) completed the same protocol. Continuous data are presented as mean ± SD. Mean group differences were compared using an independent t-test. RESULTS: There was a significant group difference for handgrip strength (ZZ 38±10 vs MM 29±7 p=0.009) and SGRQ scores for Symptoms (ZZ 41.2±20.9 vs MM 60.0±13.8 p=0.023), Impacts (ZZ 24.4±17.4 vs MM 43.2±20.8 p=0.014), and Total (ZZ 35.6±18.2 vs MM 54.5±14.5 p=0.011). SF-36 Vitality score was higher in ZZ than MM (58.2±21.5 vs 40.5±19.6 p=0.035). CONCLUSIONS: For the same level of COPD and similar body composition, fitness and upper body strength, ZZ patients present with significantly lower SGRQ scores and significantly higher SF-36 scores than MM patients.