Reliability and Learning Effect of the Glittre ADL-Test in Patients with Chronic Obstructive Pulmonary Disease

The Glittre ADL-test (TGlittre) is a multiple-task test designed to assess functional limitation in patients with chronic obstructive pulmonary disease (COPD). Although few studies have investigated the TGlittre learning effect, the results are still conflicting. This study aimed to investigate the test-retest reliability and learning effect on TGlittre and to identify predicting factors of the learning effect in patients with COPD. Patients performed the TGlittre twice with a 30-minutes resting period between trials. TGlittre consists in measuring the time to complete five laps of a multiple ADL-like activities circuit: walking stairs, carrying a backpack, lifting objects, bending down and rising from a seated position. 124 patients with COPD were assessed [81 men; 66 ± 8 years, forced expiratory volume in one second (FEV₁) 37.1 ± 15.0%pred; TGlittre 120 ± 60%pred; six-minute walking test 75.5 ± 17.4%pred]. The time spent in TGlittre presented excellent reliability (ICC = 0.96; 95%CI 0.92 - 0.98; p < 0.001; SEM 0.46 min; MDC 1.28 min) and decreased in the retest (5.24 ± 2.31 min to 4.85 ± 2.02 min; p < 0.001). Patients presented a learning effect of 6.11 ± 11.1% in TGlittre. A lower FEV₁ (r²=0.10; p < 0.001) and a worse performance in the first TGlittre (r²=0.28; p < 0.001) are related to the improvement in performance of the second TGlittre. Although the TGlittre is reliable, patients improve their performance when performing the second test probably because they underestimate their functional capacity. These results should encourage professionals to assess TGlittre twice when using this test as an outcome measure.