A Brief Measure of Life Participation for People with COPD: Validation of the Computer Adaptive Test Version of the Late Life Disability Instrument

Psychometric properties of computerized adaptive testing for chronic obstructive pulmonary disease patient-reported outcome measurement

BACKGROUND

Computerized adaptive testing (CAT) is an effective way to reduce time, repetitious redundancy, and respond burden, and has been used to measure outcomes in many diseases. This study aimed to develop and validate a comprehensive disease-specific CAT for chronic obstructive pulmonary disease (COPD) patient-reported outcome measurement.

METHODS

The discrimination and difficulty of the items from the modified patient-reported outcome scale for COPD (mCOPD-PRO) were analyzed using item response theory. Then the initial item, item selection method, ability estimation method, and stopping criteria were further set based on Concerto platform to form the CAT. Finally, the reliability and validity were validated.

RESULTS

The item discrimination ranged from 1.05 to 2.71, and the item difficulty ranged from - 3.08 to 3.65. The measurement reliability of the CAT ranged from 0.910 to 0.922 using random method, while that ranged from 0.910 to 0.924 using maximum Fisher information (MFI) method. The content validity was good. The correlation coefficient between theta of the CAT and COPD assessment test and modified Medical Research Council dyspnea scale scores using random method was 0.628 and 0.540 (P < 0.001; P < 0.001) respectively, while that using MFI method was 0.347 and 0.328 (P = 0.007; P = 0.010) respectively. About 11 items (reducing by 59.3%) on average were tested using random method, while about seven items (reducing by 74.1%) on average using MFI method. The correlation coefficient between theta of the CAT and mCOPD-PRO total scores using random method was 0.919 (P < 0.001), while that using MFI method was 0.760 (P < 0.001).

CONCLUSIONS

The comprehensive disease-specific CAT for COPD patient-reported outcome measurement is well developed with good psychometric properties, which can provide an efficient, accurate, and user-friendly measurement for patient-reported outcome of COPD.

Responsiveness of the late life disability instrument to pulmonary rehabilitation in people with COPD

PURPOSE

To establish the responsiveness of the disability component of the Late Life Function and Disability Instrument (LLDI) and its Computer Adaptive Test (LLDI-CAT) in people with chronic obstructive pulmonary disease (COPD).

METHOD

Participants completed the LLDI, LLDI-CAT and measures of physical function, health-related quality of life (HRQOL) and symptom severity before and after pulmonary rehabilitation (PR), and global rating of change (GRC) scales at the end of PR. Responsiveness was explored by calculating correlations between LLDI and LLDI-CAT change scores and change scores on the other measures, and calculating the area under the receiver operating characteristic curve (AUC) for the ability of the LLDI and LLDI-CAT to discriminate between participants who were improved versus unchanged. We hypothesized fair correlations (-0.3 to -0.5 or 0.3 to 0.5) with other measures and considered an AUC≥0.7 acceptable. Minimal important differences (MIDs) were estimated using anchor- and distribution-based approaches.

RESULTS

Fifty participants (mean (SD) age 69.8 (7.9) years) completed the study. Only the limitation dimension of the LLDI showed improvement at follow-up (z = 2.4, p = 0.018) and was able to discriminate between participants who were improved versus unchanged (AUC 0.7 (95% CI 0.6-0.9)). Correlations between change scores were as hypothesized between the participation measures and measures of at least two other constructs.

CONCLUSION

This study provides MID values for the LLDI and LLDI-CAT to support their clinical application. The limitation dimension of the LLDI appears to be particularly responsive to PR in people with COPD.

Social Participation and Associated Factors in Individuals with Chronic Obstructive Pulmonary Disease on Long-Term Oxygen Therapy

Long-term oxygen therapy (LTOT) reduces hypoxaemia and mitigate systemic alterations in chronic obstructive pulmonary disease (COPD), however, it is related to inactivity and social isolation. Social participation and its related factors remain underexplored in individuals on LTOT. This study investigated social participation in individuals with COPD on LTOT and its association with dyspnoea, exercise capacity, muscle strength, symptoms of anxiety and depression, and quality of life. The Assessment of Life Habits (LIFE-H) assessed social participation. The modified Medical Research Council dyspnoea scale, the 6-Minute Step test (6MST) and handgrip dynamometry were used for assessments. In addition, participants responded to the Hospital Anxiety and Depression Scale (HADS) and the Chronic Respiratory Questionnaire (CRQ). Correlation coefficients and multivariate linear regression analyses were applied. Fifty-seven participants with moderate to very severe COPD on LTOT were included (71 ± 8 years, FEV₁: 40 ± 17%predicted). Social participation was associated with dyspnoea (r_s=-0.46, p < 0.01), exercise capacity (r = 0.32, p = 0.03) and muscle strength (r = 0.25, p = 0.05). Better participation was also associated with fewer depression symptoms (r_s=-0.40, p < 0.01) and a better quality of life (r = 0.32, p = 0.01). Dyspnoea was an independent predictor of social participation (p < 0.01) on regression models. Restricted social participation is associated with increased dyspnoea, reduced muscle strength and exercise capacity. Better participation is associated with fewer depression symptoms and better quality of life in individuals with COPD on LTOT.