Psychometric Validation of the Speed of Change in Feeling of Health (SCFH) Questionnaire: Findings from the NEWTON Sub-Study in Italian Asthma Patients

Purpose: Speed of clinical response to a new therapeutic intervention is a critical determinant of the overall treatment outcomes, but tools focused on asthma response speed are currently unavailable. This study aimed to validate the psychometric properties of a new questionnaire initially written in Italian, the Speed of Change in Feeling of Health (SCFH), in patients with asthma. Patients and Methods: Two hundred and seventy subjects with not-well- or poorly controlled asthma, enrolled in the Italian sites of the NEWTON real-world study, were asked to complete the provisional version of SCFH and three validated questionnaires, the Stanford Expectation of Treatment Scale (SETS), the 5-item version of the Asthma Control Questionnaire (ACQ-5), and the Global Rating Scale (GRS). Internal consistency and validity were determined. Moreover, we assessed the minimal clinically important difference (MCID) using anchor-based method. Results: One hundred and ninety-six patients completed the questionnaire at least once at 7 (±1), 14 (±2), or 30 (±3) days after starting BDP/FF NEXThaler® 100/6 μg treatment. We started from SCFH provisional questionnaire of 30 items, the internal consistency of which revealed a high redundancy (Cronbach’s alpha of 0.98), prompting its reduction to an 8-item questionnaire (SCFH-8; Cronbach’s alpha = 0.90). Known-group validity indicated significant differences in SCFH-8 scores (p = 0.0003) at 30 (±3) days after enrollment between improved and non-improved subjects, as defined by changes in ACQ-5 scores. The study confirmed the convergent validity through comparisons with the SETS and the ACQ-5 questionnaires. A clinically relevant change in feeling of health was observed in 43.3% of participants at 7 days, while the cumulative frequency of patients reporting a clinically relevant change in their feeling of health at 30 days after enrollment was 70.4%. Conclusion: The Italian version of SCFH-8 is a valid, short tool with good psychometric properties for determining the speed of change in health perception after starting treatment.