Development of the “Lower Numbness Disability Questionnaire” in postoperative patients with lumbar degenerative disease

This study aims to investigate the impact of numbness on ADL and develop the Lower Numbness Disability Questionnaire (LNDQ). In addition, this study focuses on evaluating the internal consistency and face validity of the LNDQ.

Forty-three physical therapists who had been engaged in spinal disorder rehabilitation for more than 5 years were asked to complete an open-ended questionnaire regarding ADL affected by numbness, and relevant ADL items were extracted. Based on these extracted items, a preliminary version of the LNDQ was developed using the Delphi method, consisting of 10 items: walking, prolonged standing, prolonged sitting, work, leisure activities, sleeping, stair climbing, household activities, driving, and getting up from the floor. The LNDQ is a patient-reported outcome measure that assesses 10 ADL items using a 5-point Likert scale (ranging from "not affected" to "considerably affected" and "not concerned" to "considerably concerned"). The internal consistency and face validity of the preliminary version of the LNDQ were assessed. Cronbach’s alpha coefficient was calculated to confirm internal consistency. To assess face validity, participants were asked about their "overall impression," "clarity of the questions," "relevance to their own symptoms," and "difficulty in answering." The time required to complete the questionnaire was also recorded. Additionally, the percentage of participants who reported not performing certain ADLs was calculated.

The internal consistency and face validity were examined in 8 participants (3 women, mean age ± standard deviation 65.5 ± 8.9, 5 with lumbar spinal stenosis, and 3 with intervertebral disc herniation). The Cronbach’s alpha coefficient for both affected and concerned was 0.96. No comments were made to suggest revisions to the questionnaire in terms of face validity. The mean time to complete the questionnaire was 90.4±32.3 seconds, and the percentage of participants who reported not performing certain activities was 25.0% for work and 25.0% for driving.

The LNDQ we developed has demonstrated sufficient face validity and internal consistency.

This study indicates that the developed questionnaire appropriately reflects the impact of numbness on patients' daily lives. In the future, it will be necessary to validate the reliability and validity of the questionnaire for generalization.