Cromolyn sodium for the prevention of chronic lung disease in preterm infants

Chronic lung disease (CLD) frequently occurs in preterm infants (< 37 weeks gestational age) and has a multifactorial etiology including inflammation. Cromolyn sodium is a mast cell stabiliser that inhibits neutrophil activation and neutrophil chemotaxis. Therefore it is possible that cromolyn sodium might have a role in the prevention of CLD.

in preterm infants, does the prophylactic administration of cromolyn sodium reduce the incidence of CLD, mortality or the combined outcome of mortality or CLD at 28 days of life without undue side effects?

The search strategy used to identify studies was according to the guidelines of the Cochrane Neonatal Review Group. Searches were made of MEDLINE, EMBASE, CINAHL up to and including December 2000, the Cochrane Library 2000 Issue 4, personal files and reference lists of identified trials. The following terms were used: chronic lung disease, cromolyn sodium or cromoglycate.

newborn, infant; human, clinical trial or controlled clinical trial or meta analysis or randomised controlled trial. No language restrictions were applied.

Randomised or quasi-randomised controlled clinical trials involving preterm infants. Initiation of cromolyn sodium administration during the first two weeks of life. The intervention had to include administration of cromolyn sodium by nebulizer or metered dose inhaler with or without spacer device, versus placebo or no intervention. Eligible studies had to include at least one of the following outcomes: overall mortality, CLD at 28 days, CLD at 36 weeks corrected gestational age, or the combined outcome mortality or CLD at 28 days. Secondary outcomes included number of days on oxygen, number of days on mechanical ventilation, patent ductus arteriosus (PDA), air leaks [pulmonary interstitial emphysema (PIE), pneumothorax], any grade of intraventricular haemorrhage (IVH), necrotizing enterocolitis (NEC), sepsis and adverse effects due to cromolyn sodium.

We used the standard method for the Cochrane Collaboration as described in the Cochrane Collaboration handbook. Both investigators extracted and assessed all data for each study. Any disagreement was resolved by discussion. Relative risk (RR) and risk difference (RD) with 95% confidence intervals (CI) are reported for dichotomous outcomes and weighted mean difference (WMD) for continuous data. Number needed to treat was not calculated as no outcome showed a statistically significant RD. A fixed effect model was used for meta-analysis.

Two eligible studies were identified with small numbers of infants enrolled. Prophylaxis with cromolyn sodium did not result in a statistically significant effect on the combined outcome, death or CLD at 28 days [RR 1.05 (95% CI 0.73, 1.52); RD 0.03 (95% CI -0.20, 0.27)], CLD at 28 days [RR 0.93 (95% CI 0.53, 1.64; RD -0.03 (95% CI -0.27, 0.20)], CLD at 36 weeks corrected gestational age [RR 1.25 (95% CI 0.43, 3.63); RD 0.08 (95% CI -0.29, 0.44)], CLD in survivors at 28 days [RR 0.97 (95% CI 0.58, 1.63); RD -0.02 (95% CI -0.29, 0.26)] or CLD in survivors at 36 weeks corrected gestational age [RR 1.04 (95% CI 0.38, 2.87); RD 0.02 (95% CI -0.40, 0.43)]. Prophylaxis with cromolyn sodium did not show a statistically significant difference in overall mortality [RR 1.31 (95% CI 0.52, 3.29); RD 0.06 (95% CI -0.13, 0.26)]. There were no statistically significant differences in the incidence of air leaks, NEC, IVH, sepsis, days on mechanical ventilation or PDA. No side effects were noted.

There is currently no evidence from randomized trials that cromolyn sodium has a role in the prevention of CLD. Cromolyn sodium cannot be recommended for the prevention of CLD in preterm infants. Additional clinical trials do not appear to be justified using the protocols for drug administration used to date unless a more efficient type of delivery device than the jet nebulizer is employed.