Is the 6-minute pegboard and ring test valid to evaluate upper limb function in hospitalized patients with acute exacerbation of COPD?

Background The 6-minute pegboard and ring test (6-PBRT) is a useful test for assessing the functional capacity of upper limbs in patients with stable COPD. Although 6-PBRT has been validated in stable patients, the possibility of a high floor effect could compromise the validity of the test in the hospital setting. The aim of this study was to verify the convergent validity of 6-PBRT in hospitalized patients with acute exacerbation of COPD (AECOPD). Methods A cross-sectional study was conducted in a tertiary hospital. Patients who were hospitalized due to AECOPD and healthy elderly participants, voluntarily recruited from the community, were considered for inclusion. All participants underwent a 6-PBRT. Isokinetic evaluation to measure the strength and endurance of elbow flexors and extensors, handgrip strength (HGS), spirometry testing, the modified Pulmonary Functional Status Dyspnea Questionnaire (PFSDQ-M), the COPD assessment test (CAT), and symptoms of dyspnea and fatigue were all measured as comparisons for convergent validity. Good convergent validity was considered if >75% of these hypotheses could be confirmed (correlation coefficient>0.50). Results A total of 17 patients with AECOPD (70.9±5.1 years and forced expiratory volume in 1 second [FEV1] of 41.8%±17.9% of predicted) and 11 healthy elderly subjects were included. The HGS showed a significant strong correlation with 6-PBRT performance (r=0.70; p=0.002). The performance in 6-PBRT presented a significant moderate correlation with elbow flexor torque peak (r=0.52; p=0.03) and elbow extensor torque peak (r=0.61; p=0.01). The total muscular work of the 15 isokinetic contractions of the elbow flexor and extensor muscles showed a significant moderate correlation with the performance in 6-PBRT (r=0.59; p=0.01 and r=0.57; p=0.02, respectively). Concerning the endurance of elbow flexors and extensors, there was a significant moderate correlation with 6-PBRT performance (r=−0.50; p=0.04 and r=−0.51; p=0.03, respectively). In relation to the upper-extremity physical activities of daily living (ADLs) assessed by means of PFSDQ-M, there was a significant moderate correlation of 6-PBRT with three domains: influence of dyspnea on ADLs (r=−0.66; p<0.001), influence of fatigue on ADLs (r=−0.60; p=0.01), and change in ADLs in relation to the period before the disease onset (r=−0.51; p=0.03). The CAT was also correlated with 6-PBRT (r=−0.51; p=0.03). Finally, the performance in 6-PBRT showed a significant moderate correlation with the increase in dyspnea (r=−0.63; p=0.01) and a strong correlation with the increase in fatigue of upper limbs (r=−0.76; p<0.001) in patients with AECOPD. Convergent validity was considered adequate, since 81% from 16 predefined hypotheses were confirmed. There was no correlation between 6-PBRT and patients’ height. The performance in 6-PBRT was worse in patients with AECOPD compared to healthy elderly individuals (248.7±63.0 vs 361.6±49.9 number of moved rings; p<0.001). Conclusion The 6-PBRT is valid for the evaluation of functional capacity of upper limbs in hospitalized patients with AECOPD.