Bone turnover biomarkers in COPD patients randomized to either a regular or shortened course of corticosteroids: a substudy of the randomized controlled CORTICO-COP trial

Table 2 Percentage change in CTX and P1NP levels from baseline (AECOPD) to 1- and 3-month follow-up

Total N = 318	Baseline (μg/L) N = 298	1 month (difference from baseline (95% CI)) N = 213	3 months (difference from baseline (95% CI)) *N = 193*
CTX Low-dose group	196	−20% (− 30, − 8%); p < 0.0013	− 4% (− 17, 10%); p = 0.55
CTX High-dose group	196	−26% (− 35, − 16%); p < 0.0001	−23% (− 32, − 12%); p = 0.0001
Relative difference between treatment groups^a		9% (−8, 28%); p = 0.33	24% (4, 49%); p = 0.017
P1NP Low-dose group	34	60% (47, 75%); p < 0.0001	53% (38, 69%); p < 0.0001
P1NP High-dose group	34	64% (51, 78%); p < 0.0001	63% (49, 79%); p < 0.0001
Relative difference between treatment groups^a		−2% (− 14, 10%); p = 0.70	−6% (− 18, 7%); p = 0.33
P1NP/CTX ratio Low dose group	0.11	2.18 (1.91–2.49) p < 0.0001	2.11 (1.82; 2.40) p < 0.0001
P1NP/CTX ratio High dose group	0.11	2.08 (1.81;2.39) p < 0.0001	1.70 (1.46; 1.97) p < 0.0001
Relative difference between treatment groups^a		0.95 (0.81; 1.12) p = 0.56	0.81 (0.67; 0.98) p = 0.029

^athe relative difference between groups is calculated as the time–group interaction at the specific visit
Abbreviations: CTX C-terminal telopeptide of type 1 collagen, P1NP procollagen type 1 N-terminal propeptide

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