Steroids and Height

Does the use of inhaled steroids by children affect their height as adults? Excerpts from the abstract of a study about this are given.

Read them and then answer the questions that follow. "Methods: We measured adult height in 943 of 1041 participants (90.6%) in the Childhood Asthma Management Program; adult height was determined at a mean ({SD) age of 24.9 {2.7 years.

Starting at the age of 5 to 13 years, the participants had been randomly assigned to receive 400 mg of budesonide, 16 mg of nedocromil, or placebo daily for 4 to 6 years.

Results: Mean adult height was 1.2 cm lower (95% confidence interval [CI], -1.9 to -0.5) in the budesonide group than in the placebo group (P = 0.001) and was 0.2 cm lower (95% CI, -0.9 to 0.5) in the nedocromil group than in the placebo group (P = 0.61)."

a. Identify the treatment variable and the response variable.

b. Was this a controlled experiment or an observational study? Explain.

c. Does the first interval, (-1.9 to -0.5), capture 0? What does that show?

d. From the interval, can you conclude that the use of budesonide in childhood reduces the heights of the children when they become adults? Why or why not?

e. Does the second interval, (-0.9 to 0.5), capture 0? What does that show?

f. From the interval, can you conclude that the use of nedocromil in childhood reduces the heights of the children when they become adults? Why or why not?

(Source: L. H. William Kelly et al. 2012. Effect of inhaled glucocorticoids in childhood on adult height. New England Journal of Medicine 367, 904-912.)