Validity and reproducibility of a simple upper limb functional test in subjects with COPD and asthma

Background: There are few functional tests of the upper limbs for use in clinical practice and this study proposes a simplified version of the Upper Extremity Function test (UEF_S). Aims: To investigate the validity, test-retest reproducibility, Minimal Detectable Change (MDC) and learning effect of the UEF_S in subjects diagnosed with Chronic Obstructive Pulmonary Disease (COPD) and asthma. Methods: Cross-sectional study, which included clinically stable subjects diagnosed with COPD or moderate-severe asthma and a control group. Participants performed twice the UEF_S test (outcome: number of elbow flexions in 20 sec), and also the 6-minute walk test (6MWT), handgrip strength test (HST) and the Timed-up-and-go test in usual (TUGusual) and maximum (TUGmax) speed. Results: Ninety individuals with lung disease (COPD: n= 40, age 48 [38 - 58] years; asthma: n= 50, age 68 [63 - 74] years and 90 individuals without pulmonary impairments matched by gender, age, weight, height and BMI were included. Subjects with both COPD and asthma presented worse UEF_S test than controls; P= 0.0043). The UEF_S correlated with HST (r= 0.21), TUGusual (r= -0.55), TUGmax (r= -0.48) and 6MWT (r= 0.53); P<0.047 for all. The test-retest ICC was 0.91 and the mean difference between test and retest (95%CI) was 0.022 (-8.442 – 8.487) repetitions. The MDC was 0.98 repetitions (or 2%) and 34% of the sample had better performance in the second test. Conclusions: UEF_S is a simple, valid and reproducible test to assess upper limb functionality in individuals with COPD and moderate-severe asthma. The number of elbow flexions is an easy outcome to be used in clinical practice.