Clinimetric properties of the Glasgow Health Status Inventory, Glasgow Benefit Inventory, Peak Nasal Inspiratory Flow, and 4-Phase Rhinomanometry in adults with nasal obstruction

BACKGROUND: The validity of many measurement instruments frequently used in rhinology is unknown. This study describes clinimetric properties of well-known subjective and objective outcomes, i.e., the Glasgow Health Status Inventory, Glasgow Benefit Inventory, Peak Nasal Inspiratory Flow, and 4-Phase Rhinomanometry, in adults with nasal obstruction. METHODOLOGY: Construct validity and responsiveness were determined in 111 patients. Inter-rater and intra-rater reliability were analysed in 30 patients. We assessed content validity by interviewing patients and ENT-surgeons; construct validity by comparing hypothesised associations to calculated correlations between the outcomes; inter-rater reliability by having two researchers perform objective measurements in the same patients; intra-rater reliability by having one rater administer all instruments twice within a two-week interval; and responsiveness by comparing patients scores at baseline and three months after septoplasty or non-surgical management. RESULTS: All instruments demonstrated adequate content validity, inter-, and intra-rater reliability. Analyses of construct validity yielded low Pearsons correlations between the subjective and objective outcomes. Comparing septoplasty to non-surgical management, only the Glasgow Health Status Inventory scores were different between the two groups (mean difference 10.4, 95% CI 6.9 - 13.9). CONCLUSION: All measurement instruments scored appropriately on content validity and reliability, but only the subjective GHSI scored well on responsiveness