Comment on “A systematic review of the association between pleural plaques and changes in lung function” by Kopylevet al(2014)

Authors’ response: A systematic review of the association between pleural plaques and changes in lung function

“…In summary, our systematic review and meta-analysis found statistically significant decrements in lung function in asbestos-exposed people with pleural plaques relative to exposed people without abnormalities. Our analysis does not support the suggestion 1 that the results are due to methodological limitations of the studies, undetected asbestos-related disease, a biased analysis, or the exclusion of studies. Small but significant permanent changes in group mean lung function can be indicative of functional impairment at the population level; 6 the focus on population-level versus clinical-level effects is at the heart of our and Kerper et al 's 3 differing interpretations of the observed decrement in lung function.…”

“…The other differences in the set of studies arose from our more restrictive inclusion criteria (eg, excluding studies that included people with asbestosis). We see this as an example of methodological rigour, not an ‘insufficiency’ of the search strategy as characterised in reference 1 .…”

“…We welcome the opportunity to respond to Goodman et al , 1 and to correct their misperceptions about our paper. 2 As noted in their letter, Kerper et al 3 also recently analysed lung function decrements associated with pleural plaques.…”

“…With respect to the specific points raised, 1 although we did not use the term ‘risk of bias’ (a term ie, also sometimes used for ‘internal validity’), our approach certainly meets standards of systematic review. 4 We systematically evaluated studies using predefined criteria related to study methodology and potential biases (eg, consideration of potential confounding by smoking), and incorporated this information through a series of sensitivity analyses.…”

“…Despite concerns 1 that one of the longitudinal studies 5 had no comparison population, the comparison of measured lung function to predicted lung function accounts for potential longitudinal declines due solely to increasing age and allows subjects to serve as their own comparison over time. The study 5 showed that plaques and measured lung function relative to predicted lung function both worsen over time even without additional asbestos exposure.…”