ABSTRACT
Nitrogen multiple breath washout (N2 MBW) is a sensitive method to identify peripheral airway involvement in asthma, but is a time-consuming test. The N2 vital capacity single breath (VC SBW) test offers greater time efficiency, but concordance with N2 MBW is poorly understood. The prevalence of peripheral airway abnormality was determined by N2 MBW and N2 SBW tests in 194 asthmatic subjects aged 18-1 years. N2 MBW data were related to findings in 400 healthy controls, aged 17-71 years, while N2 SBW data were compared to findings in 224 healthy controls, aged 15-65 years, to derive equipment-specific reference values. Amongst asthmatic subjects, relationships between N2 SBW and N2 MBW outcomes were studied. N2 SBW relationship with clinical history, spirometry, blood eosinophils and fraction exhaled nitric oxide (FENO) data was also explored. The prevalence of peripheral airway involvement (i.e. abnormal ventilation distribution) determined by N2 SBW-derived phase III slope (N2 SIII ) was 24·7%, compared to 44% determined by N2 MBW-derived lung clearance index (LCI) (P<0·001). Predictors of abnormal N2 SIII were older age, smoking history and lower FEV1. N2 SBW offers lower sensitivity than N2 MBW to detect small airway dysfunction in adult asthma, but may be a marker of more severe disease.
ABSTRACT
Computer administrered QoL instruments are increasingly used to assess outcomes. Our aim was to assess the feasibility and validity of an electronic version of the SEIQoL-DW. Pharmacy students (n = 40; mean age 25; 92% women) were administrated both the touch screen and the paper-and-pen versions in a cross-over study. The majority of the students (65 %) preferred the computer version, while almost a third (27%) preferred the paper and pen version. There was no overall order effect and the SEOQoL-DW index mean scores differed with 1.2 between the two versions. Those respondents completing the computer version first had higher scores than those completing the computer version second. The ICC comparing the formats was 0.77 (CI: 0.57-0.88) and the limits of agreement method showed that 85% of the observations were within +/- 1-10 units. Most students (82%) judged their QoL as being equivalent to their SEIQoL-DW score. The computer version of the SEIQoL-DW seems to be feasible and acceptable and seems to be valid alternative to the paper and pen version. However, further validation studies in larger patient populations are needed.