Table 1 shows the frequency distribution of wound area variation over the evaluated time periods for both groups.
Table 1: Frequency distribution of the variation of the wound area in the evaluated time periods, for both groups, N = 25, Niteroi, 2018
Group
|
Wound Area Variation
|
First 6 weeks
|
Last 6 weeks
|
12 weeks
|
Control*
|
Increased the area
|
1 (9,1%)
|
4 (36,4%)
|
4 (36,4%)
|
|
Did not change area
|
1 (9,1%)
|
2 (18,2%)
|
1 (9,1%)
|
|
Decreased area
|
9 (81,8%)
|
5 (45,5%)
|
6 (54,5%)
|
Intervention**
|
Increased the area
|
2 (14,3%)
|
3 (21,4%)
|
2 (14,3%)
|
Did not change area
|
0 (0,0%)
|
1 (7,1%)
|
0 (0,0%)
|
|
Decreased area
|
12 (85,7%)
|
10(71,4%)
|
12(85,7%)
|
* 2% carboxymethylcellulose hydrogel (CMC)
** rhEGF carbogel
In all periods considered, and for both control and intervention groups, there was at least 1 case of treatment failure, it means that, neither treatment was 100% effective in reducing the wound area over the 12 weeks. It was also possible to observe at least 1 case in which there was no alteration of the lesion area or in the same one that increased its area.
Also according to table 1, the treatment failure for each period were estimated for both groups. The probability of no wound reduction in the first 6 weeks for the control group was 18.2%; while in the intervention group it was 14.3%. The same calculation was made for the later period of the last 6 weeks, where the control group resulted in 54.5% while in the intervention group it was 28.5%.
The probability of no wound reduction in the 12-week total study period was 45.5% in the control group and 14.3% for the intervention group.
Thus, in all evaluated periods, the probability of failure is higher for the control treatment. The results suggest that in all evaluated periods the probability of success is higher than the treatment intervention.
3.1 Calculation of cost-effectiveness of treatment given by the average cost of each 1cm2 wound reduction.
Table 2 shows total reduction and average cost of each 1 cm2 wound reduction in the control and treatment groups in each period evaluated.
Table 2: Total cost, total reduction and average cost of each 1 cm2 wound reduction in the control and treatment groups in each period evaluated.
Variable
|
Period
|
First 6 weeks
|
Last 6 weeks
|
Total (12 weeks)
|
Control
|
Treatment
|
Control
|
Treatment
|
Control
|
Treatment
|
Sum of patient costs in this period (in U$)
|
1.877,50
|
2.066,56
|
1.335,06
|
1.727,08
|
3.212,57
|
3.793,65
|
Sum of Reduced Areas over this period (in cm2)
|
27,1
|
83,4
|
-17,4*
|
25,0
|
9,7
|
108,4
|
Average cost of 1cm2 reduction over the period
|
69,28
|
24,78
|
-
|
69,08
|
331,19
|
35,00
|
* In this group, the sum of the reduced areas in the last 6 weeks was negative, showing that, in fact, in total, the total area of wounds increased by 17.4 cm2 for the control group patients during this period.
It was observed that in the first 6 weeks, the control group spent US1877,50 dollars to obtain a total reduction of 27.1 cm2; In the same period, in the intervention group, an amount of U$2066,56 was spent resulting in a total reduction of 83.4 cm2.
The average cost in this same period was U$ 69,28 per 1cm2 reduced in the control group while in the intervention group the value was U$24,78 per cm2. These values suggest that the cost-benefit ratio in the first 6 weeks is more positive in the intervention group than in the control group.
The same calculations were performed for the last 6 weeks. During this period, U$1727,08 was spent to achieve a total reduction of 25.0 cm2 in the intervention group, leaving an average cost of U$69,08 per cm2. These results suggest that it is more expensive to reduce 1 cm2 in the last 6 weeks.
For the control group such a relationship cannot be calculated, considering the total changes in the areas, wounds generally increased rather than reduced. The sum of the changes in area left an increase of 17.4 cm2.
Considering the total study period, over the 12 weeks, the total cost with the patients in the control group was U$3212,57 dollars, for a total reduction of only 9.7 cm2.
In the same period, in the intervention group, a greater amount of U$3793,65 was spent, however, it was possible to notice a total reduction of 108,4 cm2.
The average cost in the first 12 weeks was U$331,19 per cm2 reduced in the control group and U$35,00 per cm2 in the intervention group. These results suggest that the cost-benefit ratio at 12 weeks is better in treatment than in the control group.
3.2 Calculation of average (and other statistics) of wound reduction cost 1 cm2
As shown in table 3, considering only the cases that had wound reduction, according to the statistics displayed, it was possible to evaluate that in all periods, the proportion of cases that decrease the wound is higher in the intervention group. These results suggest that the likelihood of success, ie wound reduction, is greater with intervention than with control.
Table 3: Key statistics of the cost of each reduced cm2 in the wound in cases where there was a reduction in control and treatment groups in each period evaluated.
Period
|
Group
|
n* |
p*
|
Reduction cost statistics for each reduced wound cm2 (U$ / cm2)
|
Minimum
|
Maximum
|
Mean
|
Median
|
Standard Deviation
|
C.V
|
First 6 weeks
|
Control
|
9
|
81,8%
|
13,42
|
440,98
|
132,87
|
66,11
|
139,89
|
1,05
|
Intervention
|
12
|
85,7%
|
7,78
|
331,44
|
76,57
|
19,55
|
101,70
|
1,33
|
Last 6 weeks
|
Control
|
5
|
45,5%
|
42,33
|
333,29
|
180,35
|
178,51
|
110,34
|
0,61
|
Intervention
|
10
|
71,4%
|
9,69
|
540,29
|
175,46
|
120,76
|
176,34
|
1,00
|
Total (12 weeks)
|
Control
|
6
|
54,5%
|
13,42
|
203,61
|
112,72
|
95,74
|
65,70
|
0,58
|
Intervention
|
12
|
85,7%
|
9,02
|
534,42
|
110,96
|
38,26
|
150,75
|
1,36
|
n* = number of patients who presented wound reduction in this period
p* = proportion of patients who had wound reduction in this period, estimation of the probability of a patient receiving treatment to have wound reduction in this period
In all periods evaluated, the mean reduction cost for each reduced wound cm2 is also lower in the intervention group. The same was observed for the median reduction cost for each reduced cm2.
The reduction cost of 1 cm2 presented high variability between patients in both groups in all evaluated periods, given the coefficients of variation well above 0.4.
Considering the total period of 12 weeks, it was observed that the chance of a patient undergoing the intervention to have wound reduction is 85.7%. However, this 1 cm2 reduction cost measure shows high variability (CV = 1.36) in the range of 9,02 to U$534,42 / cm2, with an average of U$110,96 / cm2 and a median of 38,26 U$ / cm2.
These results suggest that the chance of a patient undergoing control treatment to have wound reduction within 12 weeks of treatment is considerably lower, at only 54.5%. The cost of reduction of 1 cm2 in this period presented high variability (CV = 0,58) in the range of 13,42 to 203,61 U$ / cm2, with an average of U$ 112,72 / median of 95,74 U$ / cm2.
In all evaluated periods, the average and median reduction cost for each reduced wound cm2 is lower in the intervention group.