Abstract
Background: We aimed to assess long-term spirometry precision using Spirometry Longitudinal Data Analysis (SPIROLA), software {1].
Methods: Retrospective data from consenting patients were entered into SPIROLA.
Results: Table 1 shows the precision found for patients as a) a whole, b) with asthma patients excluded, and also c) asthma patients alone. Figure 1 show mean pair-wise within-person FEV1 relative standard deviation over time for these groups. Mean yearly FEV1varied between 19-22 mL with z scores ranging between -1.91 to -1.49. The COV for FEV1 was 7.6% in the group of patients excluding asthma
Discussion: Hnizdo et al. suggest that sr should be < 4%, however, our study found long-term patient testing in our laboratory is less precise. An increase in within-subject variability in FEV1 has previously been observed among patients compared with the general population. Our results were obtained on multiple machines and performed by multiple operators. Further work to establish the standard that can be expected for long-term precision of patients' spirometry and to evaluate decline in FEV1 needs to be done.
Reference 1. Hnizdo et al. Open Med Informat J, 2010; 4: 94-102..
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