Development of the headache activities of daily living index: initial validity study

The purpose of this study was to develop a novel instrument for assessing headache-related disability focusing solely on important activities of daily living.

Part 1: A literature search was conducted in PubMed and Google Scholar, supplemented by hand searches in bibliographies to retrieve the original article for any instrument for the assessment of headache-related disability. Each instrument was evaluated for item categories, specific item content, measurement scale format for each item, and instructions to users. Together, these features constituted the construct validity of these instruments. Qualitative evaluations of these results were summarized with respect to the adequacy of each component. Psychometric features such as reliability and validity were not assessed. Part 2: An existing instrument for assessing self-rated disability, the Neck Disability Index, was modified for content and format and subjected to 2 rounds of clinician and patient review. Item contents and formats received final consensus, resulting in a 9-item instrument: the Headache Activities of Daily Living Index (HADLI). This instrument was tested in a sample of headache patients. Cronbach α and individual item correlations were obtained. Principal Components Analysis was performed.

Part 1: The search identified 6 reports on 5 preexisting instruments for self-rating of headache-related disability. Problems in content were found in all instruments, especially relating to the lack of items for specific activities of daily living. Problems were noted in most of the instruments for scaling and instructions with respect to the effect of headache on activities of daily living. Part 2: The authors first identified suitable items from an existing instrument for self-rating of disability. These were supplemented by items drawn from the literature. A panel of 3 clinicians and 2 laypersons evaluated these items. Two more focus groups of 7 headache sufferers each reviewed the new instrument. After this, a 9-item instrument for assessing activities of daily living in headache sufferers, the HADLI, was finalized. After this, 53 participants were recruited to study the face validity of the instrument. The sample consisted of 41 women and 12 men with a mean age of 37.3 (12) years; mean duration of headaches was 7.4 (8.3) years; mean frequency of headaches per week was 3.4 (2.4); and the intensity was 6 (2.4). The mean HADLI score was 26.2 (13.4), or 52%. There were no floor or ceiling effects for total score. The total Index Cronbach α was 0.96. The Principal Components Analysis identified one component which accounted for 75% of the variance.

The HADLI was created using theory and empirical-based methods. Face validity was assessed by focus group input and by first-level psychometrics. The HADLI has good face validity and is suitable for further reliability and validity testing.