Table 2.

Mean Annual Rate of Change in Percent Emphysema, by to Baseline Plasma Sphingomyelin Level.

Quintiles of Plasma Sphingomyelin
	Q1	Q2	Q3	Q4	Q5	Mean Annual Change in Percent Emphysema per 1 standard deviation increase in baseline SM	p- Value*
Model 1	Ref.	0.003	0.016	0.103	0.247	0.105 (0.015, 0.195)	0.022
Model 2	Ref.	0.031	0.034	0.152	0.263	0.119 (0.020, 0.219)	0.019

Model 1 controlled for age, gender, race, height, weight, BMI, scanner model and protocol.

Model 2 included model 1 variables and further controlled for educational attainment, number of cigarettes smoked per day among current smokers, cumulative pack-years, urinary levels of cotinine at baseline exam, family history of emphysema, having asthma before the age of 45, total serum cholesterol, HDL, LDL, triglycerides, intake of lipid lowering agents, systolic and diastolic and blood pressure, and study field center.

^*P-value for the relationship of mean annual change in percent emphysema to sphingomyelin level expressed as a continuous variable.