Serum creatinine/cystatin C ratio is a surrogate marker for sarcopenia in patients with idiopathic pulmonary fibrosis

Table 4 Multiple linear regression analysis for the scores of patient-reported outcomes (PROs)

	B	95% CI	β	P value
mMRC
Serum Cr/CysC ratio	− 2.54	− 4.64 to − 0.44	− 0.23	< 0.05
Age	− 0.26	− 0.66 to 0.01	− 0.17	0.19
FVC, percent predicted	0.02	− 0.01 to − 0.39	0.25	0.06
DL_CO, percent predicted	− 0.01	− 0.02 to 0.01	− 0.08	0.49
6MWT, distance	− 0.01	− 0.10 to − 0.03	− 0.44	< 0.001
6MWT, lowest SpO₂	− 0.11	− 0.16 to 0.07	− 0.58	< 0.001
CAT
Serum Cr/CysC ratio	− 23.5	− 43.1 to − 3.72	− 0.34	< 0.05
Age	− 0.32	− 0.69 to 0.06	− 0.28	0.10
FVC, percent predicted	0.13	− 0.06 to 0.32	0.22	0.18
DL_CO, percent predicted	0.01	− 0.14 to 0.16	0.02	0.93
6MWT, distance	− 0.02	− 0.05 to 0.02	− 0.17	0.30
6MWT, lowest SpO₂	− 0.82	− 1.26 to − 0.38	− 0.59	< 0.01
K-BILD (breathlessness and activities)
Serum Cr/CysC ratio	66.9	29.5–104.3	0.53	< 0.01
Age	0.92	0.21–1.63	0.39	< 0.05
FVC, percent predicted	− 0.32	− 0.67 to 0.04	0.27	0.08
DL_CO, percent predicted	− 0.09	− 0.19 to 0.37	0.09	0.53
6MWT, distance	0.06	− 0.01 to 0.12	0.29	0.06
6MWT, lowest SpO₂	1.35	0.51–2.18	0.46	< 0.01
K-BILD (total)
Serum Cr/CysC ratio	30.4	2.31–58.5	0.38	< 0.05
Age	0.57	0.04–1.10	0.38	< 0.05
FVC, percent predicted	− 0.17	− 0.44 to 0.10	− 0.23	0.21
DL_CO, percent predicted	0.04	− 0.17 to 0.26	0.07	0.67
6MWT, distance	0.04	− 0.01 to 0.08	0.28	0.13
6MWT, lowest SpO₂	0.70	0.07–1.33	0.38	< 0.05

mMRC modified Medical Research Council, Serum Cr/CysC ratio serum creatinine/cystatin C ratio, FVC forced vital capacity, DL_CO diffuse capacity of the lung for carbon monoxide, 6MWT 6-min walk test, SpO₂ oxygen saturation by pulse oximetry, CAT chronic obstructive pulmonary disease assessment test, K-BILD King's brief interstitial lung disease

ISSN: 1471-2466