CYSTIC FIBROSIS RELATED DIABETES IS NOT INDEPENDENTLY ASSOCIATED WITH INCREASED STENOTROPHOMONAS MALTOPHILIA INFECTION: LONGITUDINAL DATA FROM THE UK CF REGISTRY
Freddy Frost1, Dilip Nazareth1, Matt Shaw2, Martin Walshaw1
1Regional Adult CF Centre, Liverpool Heart and Chest Hospital, Liverpool, L143PE, UK
2Clinical Information Analyst, Research Department, Liverpool Heart and Chest Hospital, Liverpool, L14 3PE, UK
What was your research question?
Is a bacterium called Stenotrophomonas maltophilia more common in people with cystic fibrosis related diabetes (CFRD)?
Why is this important?
Stenotrophomonas is bacteria that can be found in the sputum of about 10 percent of people with CF. The clinical importance of Stenotrophomonas is uncertain with some studies showing it can be harmful and others showing it isn’t harmful. In order to better understand Stenotrophomonas, we must understand which people are more at risk of infection. We know from previous smaller studies that people with more severe lung disease are at higher risk of Stenotrophomonas infection. Recently CFRD has also been suggested to be a risk factor. As it is important to understand who is at risk of infection and why, we set about investigating the relationship between Stenotrophomonas and CFRD in more detail.
What did you do?
We used national registry data from the UK CF Registry to investigate whether having CFRD was a risk factor for acquiring Stenotrophomonas. We first looked to see if Stenotrophomonas was more common in people with CFRD versus those without CFRD, and then did further statistical analysis to allow a fair comparison.
What did you find?
Using national registry data allowed us to look a large number of people with CF and Stenotrophomonas and compare them to people with CF but no Stenotrophomonas. Initially we found that Stenotrophomonas was more common in people with CFRD. However, when we took the severity of CF lung disease into account using statistical methods, it seemed that actually CFRD is not a risk factor for Stenotrophomonas infection.
What does this mean and reasons for caution?
Our findings indicate CFRD isn’t an independent risk factor for Stenotrophomonas. People with CFRD often have more severe lung disease. It appears that those risk factors, rather than CFRD itself, are responsible for the increased Stenotrophomonas in people with CFRD. One reason for caution is that with registry based data there is a risk that the results may be confounded by bias arising from how data is collected or reported. Other studies have found a relationship with Stenotrophomonas and early stages of diabetes. We weren’t able to tell how long people had had CFRD in our study so we can’t rule out different results in early diabetes.
To confirm the findings of this study we are exploring ways to see if Stenotrophomonas rates are similar in people with the early stages of diabetes.