PASSIVE SMOKING AND LUNG-FUNCTION IN CYSTIC-FIBROSIS

The relationship between passive exposure to cigarette smoking and obj ective measures of health was examined in 340 patients with cystic fib rosis attending a large hospital-based clinic. Patients who came from households with smokers did not differ from those living in smoke-free households in terms of nutritional status, clinical scores, spirometr y, or colonization with Pseudomonas. The number of cigarettes smoked i n the household was not significantly related to nutritional status, c linical score, spirometry, or hospitalization. Similar results were fo und when children 6 to 11 yr of age were analyzed separately, except t hat height percentile was negatively related to the number of cigarett es smoked in the household. The effects of household exposure to cigar ette smoke were further evaluated by analyzing changes in nutritional status, clinical score, and spirometry over a 15-yr period among patie nts whose families never, always, stopped, or started smoking during t his time. Height percentile increased slightly during this interval am ong those whose households never smoked, whereas no change occurred am ong patients whose households always smoked, and a decline was seen am ong patients whose households quit. These differences were statistical ly significant. Patients whose households never smoked had consistentl y higher pulmonary function measurements than did patients whose famil ies always smoked, although the differences were not statistically sig nificant. The rates of decline were similar in these two groups. Patie nts whose households stopped smoking had significantly lower pulmonary functions at the end of the study than did subjects whose households never smoked. When patients who were homozygous for the Delta F-508 mu tation were analyzed separately, results were similar. The longitudina l analysis suggests that a ''healthy smoker effect,'' whereby families of individuals least affected by respiratory disease are more likely to continue smoking, may have occurred.