Psychometric Evaluation of the Bahasa Malaysia Version of the Lymphedema Functioning, Disability, and Health Questionnaire for Upper Limb Lymphedema in Patients with Breast Cancer-Related Lymphedema.

Breast cancer-related lymphedema (BCRL) is the most prevalent comorbidity that occurs following breast cancer treatments and has negative impact on the patients' quality of life (QoL). The Lymphedema Functioning, Disability, and Health Questionnaire for Upper Limb Lymphedema (Lymph-ICF-UL) is a valid and reliable instrument in assessing the QoL of patients with BCRL. However, the Bahasa Malaysia (BM) version is not available yet. This study aimed to translate the Lymph-ICF-UL into BM and to evaluate its validity and reliability. A forward-backward translation was performed based on Sousa's guideline, and then, the face, content, construct validity, internal consistency, and test-retest reliability were tested. Face validity was assessed by five patients, and content validity was evaluated by six experts. Then, construct validity and internal validity were assessed in 107 patients. Finally, test-retest reliability was analyzed in 21 patients. Two items were eliminated following suggestions from the patients and experts. All patients found the scoring system and items clear and relevant. The results showed sufficient content validity index and modified kappa statistics value. Confirmatory factor analysis showed acceptable fit indices. Cronbach's alpha values ranged from 0.67 to 0.95, intraclass correlation coefficient ranged from 0.88 to 0.99, standard error measurement was 2.29-6.15, and the Bland-Altman plot showed an agreement between two test occasions. These results suggested that the Lymph-ICF-UL BM has good validity and reliability in evaluating the QoL of patients with BCRL in Malaysia.