We wanted to know if CF centres with patients averaging the lowest lung function (meaning worse outcomes) were using less intravenous (IV) antibiotics compared to centres with patients averaging higher lung function (meaning better outcomes).
Why is this important?
North American data from 1994-1995 and 2003-2005 showed that centres with the lowest lung function scores also used less IV antibiotics. This is a little surprising, because people with lower lung function tend to be more prone to exacerbations (episodes of worse symptoms / infection), and so are expected to need more IV antibiotic therapy. The results could suggest that centres with lower lung function are not treating patients with enough IV antibiotics.
We expect that CF centres nowadays are less dependent on IV antibiotics to maintain lung function. This is due to the availability of powerful treatments to prevent exacerbation, e.g. inhaled antibiotics and mucolytics (which help patients clear mucus). Neither of these were available before the late 1990’s but are now increasingly prescribed.
What did you do?
We analysed 2013-2014 data from the UK CF registry using similar method as for the 1994-1995 study, so that our results could be compared. This involved dividing 28 CF centres into 3 different groups based on lung function, then comparing IV antibiotic use between groups of people with similar lung function.
We also used other statistical modelling to check that our results are accurate and if differences in lung function could be influenced by the prescription of preventive treatments, such as inhaled antibiotics.
What did you find?
CF centres with the lowest lung function scores were still using less IV antibiotics compared to centres with higher lung function scores. On the other hand, prescription of preventive treatments, such as inhaled antibiotics, did not appear to explain the differences in lung function between centres.
What does this mean and reasons for caution?
Our results suggest that despite the wide availability of preventive treatments, inadequate IV antibiotic use could still affect lung function for people with CF, at a centre level. We suspect that lower lung function scores could be the result of inadequate detection and treatment of exacerbations.
However, preventive treatment still has an important role in maintaining lung function. Such treatments work well in a clinical trial setting, when adherence (taking medication as prescribed) is typically 80-100%. However, in real life, adherence tends to be much lower, around 35-50%.
A UK national programme is underway to measure adherence of preventive inhaled treatments in CF centres. Analysing IV antibiotic use along with adherence to preventive treatments would help us understand more about the quality of care in CF.