Lymphoedema Functioning, Disability and Health questionnaire (Lymph-ICF): reliability and validity.

Background: Lymphedema occurs frequently after axillary dissection for breast cancer and causes significant physical and psychosocial problems. To plan the treatment for lymphedema and monitor the patient's progress, arm swelling and arm function need to be assessed.

Objective: The purpose of this study was to investigate the reliability (test-retest, internal consistency, measurement variability) and validity (content and construct) of data obtained with the Lymphoedema Functioning, Disability and Health questionnaire (Lymph-ICF).

Methods: The Lymph-ICF is a descriptive and evaluative tool and consists of 29 questions about impairments in function, activity limitations, and participation restrictions of patients with breast cancer and arm lymphedema. The questionnaire is divided into 5 domains: physical function, mental function, household activities, mobility activities, and life and social activities. Reliability and validity were examined on 60 patients with lymphedema and 30 patients without lymphedema.

Results: Intraclass correlation coefficients for test-retest reliability ranged from .65 to .93. Cronbach alpha coefficients for internal consistency were higher than .70. There were no systematic changes from the first test to the second test, and measurement variability was acceptable (standard errors of measurement=4.8-12.5). Content validity was good because all questions were understandable for all participants, the scoring system (visual analog scale) was clear for 88% of the participants, and all complaints due to arm lymphedema were mentioned by 85% of the participants. Construct validity was good. There was good convergent validity because 5 expected domains of the Lymph-ICF had the strongest correlation with 5 expected domains of the 36-Item Short-Form Health Survey questionnaire (SF-36). Thus, the 5 hypotheses assessing convergent validity were accepted. There was acceptable divergent validity because 3 of 5 hypotheses assessing divergent validity were accepted. There was good known-groups validity because patients with lymphedema had a higher total score on the Lymph-ICF and had a higher score on each domain and on each question (except one) compared with patients without lymphedema.

Conclusion: The Lymph-ICF is a reliable and valid questionnaire to assess impairments in function, activity limitations, and participation restrictions of patients with arm lymphedema after axillary dissection for breast cancer.