Tobi Article

[Guest guest]

Mortality of cystic fibrosis patients treated with tobramycin solution

for inhalation.

Rothman KJ, Wentworth CE 3rd.

BACKGROUND Tobramycin solution for inhalation (TOBI; TSI) is indicated

to treat patients with cystic fibrosis who are infected with Preliminary

findings from a randomized trial indicate that patients who received TSI

had about half the mortality rate of those assigned to placebo.

METHODS We used the Cystic Fibrosis Foundation registry data to conduct

a retrospective cohort study of the risk of death among cystic fibrosis

patients in 1999 according to their use of TSI during 1998. We

controlled for age, lung function, height and infection with; other

factors were not important confounders.

RESULTS The crude risk of death among those who received TSI therapy for

4 or more months was 3.5 times greater than that among those who

received no TSI (90% confidence interval = 3.0-4.2). In general,

increased TSI use was related to progressive increases in the risk of

death. Such a relation is expected because TSI is used for those who are

close to death, resulting in strong confounding by indication. After

control of the previously mentioned confounders, the estimated risk

ratio was reduced from 3.5 to 1.2. Unfortunately, it is difficult to

remove confounding by indication in its entirety. Using a method that

estimates the magnitude of uncontrolled confounding, we show that the

actual relation between TSI and the risk of death is likely to be

protective, and may well be consistent with the results from the

randomized trial.

CONCLUSIONS These data illustrate strong confounding by indication and

the extent to which the interpretation of data can rest on assumptions

about the data and its residual biases.

Becki

YOUR FAVORITE LilGooberGirl

YOUNGLUNG EMAIL SUPPORT LIST

www.topica.com/lists/younglung

Pediatric Interstitial Lung Disease Society

http://groups.yahoo.com/group/InterstitialLung_Kids/