Standards of care for patients with cystic fibrosis (CF) have been defined largely on the basis of “best practice”, an accolade awarded to treatment regimens showing low chronic pulmonary infection rates, greatest patient longevity, and least patient morbidity. While acknowledging the wisdom accrued through clinical experience, paediatricians caring for children with CF are fighting for limited resources and must convince purchasers, who stroll the fashionable catwalk of evidence based medicine, of the scientific basis of our demands. They ask, “Where’s the beef?” For the use of nebulised antibiotics in CF care we can reply only that we have a lot of “topside” but few “prime cuts”.

Clinical trials, the results of which affect all of our prescription practices, have been generally parochial in conception, bedevilled by small patient numbers, and underpowered, partly reflecting patient recruitment problems for research into an illness that affects only a small minority of the population and, until recently, a lack of multicentre trials. In his meta-analysis of the benefits and risks of nebulised antibiotic treatment in CF, Mukhopadhyayet al suggested that a definitive study would need 500 patients, the minimum that would allow for imbalances in patient characteristics that are not amenable to adjustments in the analysis.1 In Ramsey’s study of TOBI, a preservative free preparation designed for nebulisation, over 80% of almost 500 patients completed the trial,2 but the most comprehensive published multicentre study at the time of writing has only 71 patients.3 The antibiotics studied (gentamicin, tobramycin, colistin, ceftazidime), the antibiotic dose (20 mg to 600 mg of aminoglycoside), the type of nebuliser used, and the length of treatment have varied, making comparison between trials difficult.