NUTRITIONAL GROWTH-RETARDATION IS ASSOCIATED WITH DEFECTIVE LUNG GROWTH IN CYSTIC-FIBROSIS - A PREVENTABLE DETERMINANT OF PROGRESSIVE PULMONARY DYSFUNCTION

Evidence for a relationship between nutritional growth retardation in cystic fibrosis (CF) and progressive pulmonary dysfunction was evaluat ed by a prospective longitudinal study of changes in nutritional growt h parameters, in relation to changes in pulmonary function data, in 61 moderately affected CF patients, aged 5-17 yr, during the equilibrate d phase of lung growth. Age, sex, initial and serial weight and height Z scores, body cell mass (BCM) by total-body potassium (TBK) analysis , and changes in forced expiratory volume in 1 s (FEV(1)) and forced v ital capacity (FVC), excluding data during pulmonary exacerbations, we re analyzed by multiple regression analyses. The only significant pred ictor of change in EVC (best-fit model) was change in BCM, expressed a s TBK (g/yr), TBK for age (percentage predicted), and TBK for height ( percentage predicted) (p < 0.01). Standard anthropometric variables we re not predictive. No reliable predictive model emerged for changes in FEV(1). Relative decline in TBK for age was strongly predictive of de cline in FVC (percentage predicted) accounting for 23% of this change. Patients with normal growth of the BCM had significantly less decline in EVC than those with retarded growth of the BCM (a fall of 2.5 vs. 6.8%/yr, p < 0.01). Impaired growth of the metabolically active BCM ap pears to be associated with progressive lung dysfunction in CF, possib ly mediated by impaired lung growth. Achieving optimal nutrition and g rowth may minimize the progressive decline in pulmonary function commo nly seen in this disease.