Topical cutaneous application of carbon dioxide via a hydrogel for improved fracture repair: results of phase I clinical safety trial

Table 5 Sub-group analysis regarding the influence of age on the increase in blood flow by the CO₂ therapy in the fractured limb of patients

Measuring site	Treatment day	Age	n	Mean (range) [95%CI]	p-value (1)	p-value (2)
Fracture level	1	≤45	9	1.221 (0.970–1.473) [1.106–1.336]	0.008	0.030
	1	> 45	10	1.589 (1.146–2.846) [1.238–1.940]	0.002	0.030
	14	≤45	9	1.750 (1.184–3.152) [1.289–2.211]	0.004	0.97
	14	> 45	10	1.777 (1.156–2.829) [1.372–2.181]	0.002	0.97
	28	≤45	9	2.101 (1.326–5.100) [1.135–3.068]	0.004	0.97
	28	> 45	10	2.170 (1.236–4.471) [1.432–2.907]	0.002	0.97
5 cm from the fracture level	1	≤45	9	1.453 (1.010–1.705) [1.290–1.615]	0.004	0.77
	1	> 45	10	1.501 (1.060–2.000) [1.260–1.742]	0.002	0.77
	14	≤45	9	1.811 (1.314–2.440) [1.506–2.116]	0.004	0.78
	14	> 45	10	1.895 (1.168–2.660) [1.490–2.300]	0.002	0.78
	28	≤45	9	1.908 (1.279–2.625) [1.507–2.309]	0.004	0.71
	28	> 45	10	2.077 (1.038–3.431) [1.555–2.600]	0.002	0.71

Blood flow increase is demonstrated by the ratio of blood flow measured after 20 min of CO₂ therapy to that at pre-treatment. n: number of patients. p-value (1): calculated using Wilcoxon signed rank test with a null hypothesis that the population mean of the blood flow ratio is 1. p-value (2): calculated using Mann–Whitney U test to compare the two groups (Age ≤ 45 versus > 45)

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