Aetiology

You just never know where the next insight is going to come from. An observation that surfers with cystic fibrosis (a genetic disease that results in mucus build-up in the lungs leading to an increased susceptibility to infection) reported breathing easier after spending time out on the water led researchers to test salt water as a treatment for the disease. A new study inThe New England Journal of Medicine shows that it worked in their pilot studies.

Patients were given either a 7% or a .9% saline solution to inhale twice a day for 48 weeks. A number of outcomes were measured, including counts of a variety of bacteria, quality of life, lung function, and disease exacerbations requiring antibiotic treatment. Bacterial counts and types didn't differ significantly, but exacerbations did decrease in the 7% saline group--and when they occurred, they resolved faster:

There were fewer exacerbations requiring intravenous antibiotic therapy in the hypertonic-saline group than in the control group. The mean number of exacerbations per participant in the control group was 0.89, as compared with 0.39 in the hypertonic-saline group (difference, 0.5; 95 percent confidence interval, 0.14 to 0.86; P=0.02). The mean number of days on which participants met this exacerbation definition was 17 days in the control group and 6 days in the hypertonic-saline group (difference, 11 days; 95 percent confidence interval, 3 to 19; P=0.02). The interval during which participants remained free of exacerbations was significantly longer in the hypertonic-saline group than in the control group (P=0.03), with a 48-week exacerbation-free survival rate of 76 percent in the hypertonic-saline group and 62 percent in the control group.

When exacerbations were defined according to signs and symptoms alone, regardless of treatment, results again favored the hypertonic-saline group. The mean number of exacerbations defined in this way was 2.74 per participant in the control group and 1.32 in the hypertonic-saline group (difference, 1.42; 95 percent confidence interval, 0.86 to 1.99; P<0.001). The mean number of days during which participants met criteria for a symptom-defined exacerbation was 69 days in the control group and 22 days in the hypertonic-saline group (difference, 47 days; 95 percent confidence interval, 30 to 63; P<0.001). The time participants remained free of exacerbations was significantly longer in the hypertonic-saline group (P<0.001), with a 48-week exacerbation-free survival rate of 41 percent in the hypertonic-saline group and 16 percent in the control group.

Accordingly, many quality of life measurements increased in the treated group as well.

A second study in the journal suggests a mechanism for these improvements:

On the basis of studies of airway epithelia in vitro, it appears likely that the mechanism of action of hypertonic saline is to provide long-term hydration of airway surfaces and promote a sustained increase in mucus clearance. This study points to a vital therapeutic role for the restoration of hydration to airway surfaces in patients with cystic fibrosis and suggests that measures of sustained mucus clearance may serve as a useful surrogate outcome for future drug development.

Obviously, the Cystic Fibrosis Foundation is excited about the possibility of this as a treatment:

"This innovative new therapy is just one of the many novel CF treatments we have in our drug discovery and development pipeline," said Robert J. Beall, Ph.D., president and CEO of the Cystic Fibrosis Foundation. He added, "When researchers proposed this study to us, we were eager to provide support to evaluate the treatment as safe and effective, then get it quickly to CF patients."

Though this is promising, there are still hurdles. Less than 2/3 of the test subjects in each group (7% and .9% saline) completed the therapy. The solution had to be inhaled for 15 minutes--probably one reason for the drop-out rate. Additional studies are underway to figure out ways to reduce this time, or potentially use something other than salt to acheive the same effect. It's not as good as a cure, but it's a step forward.

Cystic fibrosis