The Severe Respiratory Insufficiency Questionnaire was valid for COPD patients with severe chronic respiratory failure

Abstract

Objectives The Severe Respiratory Insufficiency (SRI) Questionnaire has recently been developed and validated for the assessment of health-related quality of life (HRQL) in patients with severe chronic respiratory failure resulting from a broad spectrum of underlying disorders. The present study was aimed at reexamining the internal structure of the SRI specifically for chronic obstructive pulmonary disease (COPD) patients. Study Design and Setting Cross-validation was performed in two COPD groups ( N = 78 and N = 84), each receiving home mechanical ventilation in addition to long-term oxygen therapy. The internal consistency reliability was calculated using Cronbach's α coefficient. Explorative Factor Analysis was performed followed by Confirmatory Factor Analysis to establish construct validity. Results In the total group ( N = 162) Cronbach's α ranged from 0.73 to 0.88. Only one factor could be established which explained 58.5% of the total variance confirming one Summary Scale (SRI-SS). For each of the seven subscales, Confirmatory Factor Analysis revealed two factors, which were substantially correlated ( r = 0.43–0.80). All scale scores covered a broad range of the questionnaire's scaling range (0–100). The mean SRI-SS score was 52 ± 17 indicating a homogenous scaling distribution. Conclusion The SRI is a multidimensional and highly specific tool with high psychometric properties for HRQL assessment in COPD patients with severe chronic respiratory failure.