Pulmonary function correlates in the prediction of long-term weight gain in cystic fibrosis patients with gastrostomy tube feedings.

BACKGROUND: Gastrostomy tube feedings have a positive effect on nutritional status and are currently recommended for cystic fibrosis patients who fall below 85% ideal weight for height. However, the impact of pulmonary function at the time of gastrostomy tube placement on long-term nutritional status has not been ascertained.
METHODS: We retrospectively evaluated whether nutrition status and/or pulmonary function at gastrostomy tube placement surgery were predictive of subsequent long-term (> or =2 yrs) weight velocity. We identified 21 cystic fibrosis patients (12 male), ages 5-18 years at gastrostomy tube insertion. Patients were divided into two groups according to their weight gain response after 2 years on gastrostomy tube feeding. Responders were defined as having a positive change in weight/age z-score (deltaWAZpost) at 2 years follow-up compared to the 2 year period preceding gastrostomy tube insertion (deltaWAZpre). Nonresponders were defined as having a negative WAZpost.
RESULTS: Responders had significantly better FEV1 at surgery (61 +/- 26 [SE] vs. 24 +/- 3 %pred.; p < 0.05). In responders, epsilonWAZpre was -0.37 +/- 0.08 and was -0.46 +/- 0.07 in nonresponders (p-NS). In contrast, AWAZpost was 0.92 +/- 0.11 in responders and -0.40 +/- 0.07 in nonresponders (p < 0.001). Furthermore, a significant correlation between weight/age z-score change and pulmonary function was found when FEV1 <40% predicted (r = 0.88; p < 0.004) whereas no significant correlation was present when FEV1 > or =40% predicted.
CONCLUSIONS: We conclude that the long-term nutritional benefit of gastrostomy tube placement is critically dependent on pre-surgical pulmonary function. Our findings suggest that gastrostomy tube insertion in malnourished cystic fibrosis patients should be considered an early intervention rather than one of last resort.