Patient-reported outcomes are seldom validated measures in clinical trials of acute respiratory tract infections (ARTIs) in primary care. We developed and validated a patient-reported outcome sum-scaling measure to assess the severity and functional impacts of ARTIs.
Qualitative interviews and field testing among adults with an ARTI were conducted to ascertain a high degree of face and content validity of the questionnaire. Subsequently, a draft version of the Acute Respiratory Tract Infection Questionnaire (ARTIQ) was statistically validated by using the partial credit Rasch model to test dimensionality, objectivity, and reliability of items. Test of known groups’ validity was conducted by comparing participants with and without an ARTI.
The final version of the ARTIQ consisted of 38 items covering five dimensions (Physical-upper, Physical-lower, Psychological, Sleep, and Medicine) and five single items. All final dimensions were confirmed to fit the Rasch model, thus enabling sum-scaling of responses. The ARTIQ scores in participants with an ARTI were significantly higher than in those without ARTI (known groups’ validity).
A self-administered, multidimensional, sum-scaling questionnaire with high face and content validity and adequate psychometric properties for assessing severity and functional impacts from ARTIs in adults is available to clinical trials and audits in primary care.