Study Validates RiiQ Symptoms Scale for Assessing RSV Symptoms, Severity

After applying an extensive range of psychometric tests to the symptoms summary scores of the Respiratory Infection Intensity and Impact Questionnaire (RiiQ)—a patient-reported outcomes (PROs) measure for evaluating respiratory syncytial virus (RSV) symptoms and impacts—researchers found that the questionnaire has reliability, construct validity, discriminating ability, and responsiveness for use in clinical studies on RSV symptom onset and severity.

Findings were published in the Journal of Patient-Reported Outcomes.

Prospective data from 1795 participants were analyzed. Most participants came from a phase 2b RSV vaccine study of nonhospitalized patients with acute respiratory infection (ARI) and no coinfections, of whom 60 had RSV and 1615 did not. Another 120 patients came from 2 observational studies of patients hospitalized with RSV.

Of the participants with RSV, the mean (SD) patient age ranged from 66.5 (17.9) to 71.5 (5.1) years, and the mean number of comorbidities ranged from 1.5 (1.1) to 2.7 (2.0). Most of the included participants were female, which was also true for all 3 studies included.

It is also important to note that the vaccine study was conducted in the United States and the sample was almost entirely non-Hispanic White, whereas the observational studies were conducted globally with more diversity.

Various statistical analyses were conducted to assess the data. These included descriptive statistics, confirmatory factor analysis (CFA), test-retest intraclass correlation coefficients (ICCs), construct validity correlations between a clinician-assessed clinical questionnaire and the RiiQ symptoms scale, known groups validity, and responsiveness examining correlations between change scores.

The RiiQ items demonstrated logical patterns of upper and lower respiratory symptoms among the study participants. Those in the vaccine study displayed fewer symptoms during the initial stages of RSV infection compared with those hospitalized for ARI. By the follow-up period, symptoms had resolved in nearly all participants.

Most symptoms resolved in the 2 observational studies as well, but a significant percentage of patients—between 9% and 22%—continued to experience moderate to severe shortness of breath and cough.

As mentioned, the evaluation of the RiiQ Symptoms Scale summary scores demonstrated strong support for their structure, reliability, validity, and responsiveness. According to the authors, inter-item correlations, CFA results, and internal consistency reliability coefficients yielded generally positive outcomes, reinforcing the proposed scoring.

The 2-factor CFA model, as hypothesized by the authors, aligned with the variance-covariance matrix of respiratory-related symptom items, and Cronbach α values exceeded the threshold of 0.70. Notably, the respiratory symptoms related to lower respiratory tract (LRT) such as cough, wheezing, shortness of breath, and expectoration showed more consistent correlations compared with upper respiratory tract (URT) symptoms like nasal congestion and sore throat.

“Overall, these results support the formation of Respiratory (LRT and URT) and Systemic scores, which can be viewed as cumulative indices,” the authors said.

The study also established moderate to strong correlations between LRT symptoms summary scores and both clinical questionnaire summary scores and the Patient Global Impression of Severity (PGI-S), indicating construct validity and agreement between clinician and patient ratings. However, it is important to note that the correlations with URT symptoms summary scores were moderate among patients without RSV and smaller among patients with RSV.

The RiiQ Symptoms Scale summary scores also demonstrated responsiveness to change. Patterns of mean change and correlations between the RiiQ Symptoms Scale scores and changes in PGI-S and PGI-Health (PGI-H) scores provided evidence for its effectiveness. PGI-S and PGI-H scores reflect patient-reported changes in the severity of respiratory illness and overall health, respectively.

Although other PRO measures exist for respiratory illnesses like influenza, the RiiQ is considered a novel PRO, specifically designed for assessing RSV symptoms.

“While the two pathogens can present with similar clinical symptoms, infuenza-specifc PROs may not fully capture the unique clinical symptomatology of RSV,” the authors said. “Further, the RiiQ is a short, simple PRO measure that can easily be administered in clinical settings, in contrast to prior infuenza-specifc PRO measures. Additional studies evaluating the usefulness of the RiiQ in clinical practice are needed.”

Reference

Osborne RH, Nelson LM, Fehnel S, et al. Evaluation of symptoms in respiratory syncytial virus infection in adults: psychometric evaluation of the Respiratory Infection Intensity and Impact Questionnaire symptom scores. J Patient Rep Outcomes. 2023;7(1):51. doi:10.1186/s41687-023-00593-9