Table 2. Multivariable model of risk factors measured during the baseline year for annual change in FEV1 % predicted1.
| Risk Factor | Coefficient | 95% CI | P-value |
|---|---|---|---|
| F508del heterozygous2 | 0.39 | 0.08, 0.70 | 0.01 |
| Both mutations non-F508del2 | 0.55 | -0.07, 1.18 | 0.08 |
| Female sex | -0.60 | -0.90, -0.31 | 0.0001 |
| Frequent or productive cough | -0.31 | -0.61, -0.01 | 0.04 |
| Pulmonary exacerbation | -0.47 | -0.89, -0.06 | 0.02 |
| MSSA3 | -0.68 | -1.05, -0.31 | 0.0004 |
| MRSA3 | -1.00 | -1.51, -0.49 | 0.0001 |
| S. maltophilia positive | -0.50 | -0.93, -0.07 | 0.02 |
| Best BMI <66th percentile | -0.53 | -0.84, -0.23 | 0.001 |
| Best FEV1 ≥115 % predicted | -0.75 | -1.12, -0.38 | 0.0001 |
| Age (yrs) | 0.56 | 0.09, 1.02 | 0.02 |
Results are shown for risk factors that had a significant interaction with age. The coefficient for each risk factor reflects the difference in mean annual change in FEV1 % predicted between participants with the attribute during the baseline year vs. those in the reference category. The coefficient for age reflects the mean annualized change in FEV1 % predicted for participants whose values were in the reference category for all risk factors; coefficients for other main effect terms are not shown. Reference categories included genotype F508del homozygous, male sex, no exacerbations, absence of frequent or productive cough, S. aureus negative, S. maltophilia negative, BMI ≥66th percentile (the median value in the cohort), and FEV1 <115 % predicted (representing the lower 3 quartiles of FEV1 in the cohort). The final model was adjusted for P. aeruginosa status (any positive cultures vs. none) and Medicaid status (on Medicaid vs. not) during the baseline year and reflects data for 931 participants.
The p-value was 0.02 when both genotype terms were tested simultaneously for the overall effect of genotype on annual change in FEV1 % predicted.
S. aureus status was assigned to one of 3 mutually exclusive categories: MSSA +, MRSA +, or S. aureus negative (reference group). The p-values reflect the fact that the annual change in FEV1 % predicted for both MSSA+ and MRSA+ participants was significantly different than observed for S. aureus negative participants.