Predicting future risk of XXXX exacerbations using individual conditional probabilities.

@entity1 @entity565
BACKGROUND: Determination of future risk of exacerbations is a key issue in the management of @entity565 . We previously developed a method to calculate conditional probabilities (  ) of future decreases in lung function by using the daily fluctuations in peak expiratory flow (PEF). OBJECTIVE: We aimed to extend calculation of    values to individual @entity1 , validated by using electronically recorded data from 2 past clinical trials. METHODS: Twice-daily PEF data were analyzed from 78 @entity1 with severe (study A) and 61 @entity1 with poorly controlled (study B) @entity565 . For each @entity1 , the    value was calculated from 5000 PEF data points simulated based on the correlation and distribution properties of observed PEF. Given an initial PEF, the    value was defined as the probability of a decrease in PEF to less than 80% of predicted value on 2 consecutive days within a month. These probabilities were then compared with actual occurrences of such events and clinically defined exacerbations within the following month. RESULTS:    Values were related to actual occurrences of decreases in PEF (adjusted R(2) > 0.800 for both studies). Every increase of 10% in    value was associated with an odds ratio of having a future exacerbation of 1.24 (95% CI, 1.07-1.43) for study A  and 1.13 (95% CI, 1.02-1.26) for study B, with better sensitivity and specificity than clinic-measured FEV(1). CONCLUSION: These results from 2 independent datasets with differing asthmatic populations and differing exacerbation criteria provide support that clinically relevant quantification of individual future risk of exacerbations is possible.
