Table 2.

Effects of Inhaled Corticosteroids (ICS) Treatment on Monthly Medical Costs and Monthly Likelihood of Severe Exacerbation

	Medical Costs		Severe Exacerbation
	Coefficient	SE	Coefficient	SE
Ages 40–79 (n = 10,271)
β1 (follow-up months, time)	44.17	5.90**	0.00007	0.00004
β2 (1 month before the first bronchodilator claim, onset)	1251.17	61.45**	0.05112	0.00115**
β3 (months after the first bronchodilator claim, post onset)	−210.08	56.97**	0.00292	0.00082**
β4 (months after the first inhaled corticosteroid claim, ICS)	23.08	50.41	−0.00370	0.00078**
β5 (time×ICS)	−53.55	6.20**
β6 (time×post onset–time×ICS)	−52.18	7.92**
β5−β6	−1.37	5.59
δ1 (month with an antibiotic prescription)	877.67	29.64**	0.02518	0.00062**
δ2 (month with an oral corticosteroid prescription)	824.86	39.21**	0.06330	0.00082**
δ3 (months after the first asthma diagnosis)	452.95	36.42**	0.00327	0.00076**
δ4 (months after the first congestive hart failure diagnosis)	1943.67	51.81**	0.01731	0.00109**
Ages 50–79 (n = 8,738)
β1 (follow-up months, time)	49.15	6.62**	0.00008	0.00004*
β2 (1 month before the first bronchodilator claim, onset)	1329.56	68.95**	0.05465	0.00129**
β3 (months after the first bronchodilator claim, post onset)	−238.60	63.74**	0.00270	0.00091**
β4 (months after the first inhaled corticosteroid claim, ICS)	−4.78	56.44	−0.00377	0.00088**
β5 (time×ICS)	−58.22	6.97**
β6 (time×post onset–time×ICS)	−58.06	8.89**
β5−β6	−0.15	6.26
δ1 (month with an antibiotic prescription)	914.94	33.73**	0.02778	0.00071**
δ2 (month with an oral corticosteroid prescription)	798.38	44.47**	0.06803	0.00093**
δ3 (months after the first asthma diagnosis)	483.88	41.66**	0.00355	0.00087**
δ4 (months after the first congestive heart failure diagnosis)	1963.58	55.61**	0.01782	0.00117**

^*Statistical significance at the 5% level;

^**Statistical significance at the at the 1% level.

A Hausman specification test confirmed that the fixed-effects model was appropriate.

estimated coefficients; SE, robust standard errors.