Table 2.

Decline in Lung Function Based on Baseline Calprotectin Level

	Quintile 1	Quintile 2	Quintile 3	Quintile 4	Quintile 5	Per Twofold Increment in Baseline Calprotectin	P Value
Median calprotectin, μg/ml	4.9	6.6	10.9	16.7	24.2	—	—
FEV₁, ml
Unadjusted	−35	84	0	186	68	33 (–2 to 68)	0.06
Adjusted^*	−59	66	−51	195	65	44 (3 to 84)	0.03
FVC, ml
Unadjusted	−14	54	−22	134	175	51 (21 to 81)	<0.001
Adjusted^*	−78	−17	−122	88	89	50 (12 to 87)	0.009

The rate of lung function decline per year increases with increasing baseline calprotectin. Data are presented for both unadjusted and adjusted (for age, sex, previous exacerbation rate, symptom score, and high-sensitivity CRP).

Note that three patients did not have a baseline high-sensitivity CRP model and were excluded from the analysis for this model.