Cost and Dressing Evaluation of Hydrofiber and Alginate Dressings in the Management of Community-Based Patients withChronic Leg Ulceration
Introduction
Patients with lower leg ulceration present a complex management situation for the practicing health professional. A number of factors should be considered by health professionals, including accurate diagnosis of the ulcer etiology and the formulation of a comprehensive, affordable treatment plan.1,2
In patients with such wounds, venous disease is the most common pathology seen in clinical practice. In these patients, it is accepted that compression of the limb is an essential component of the patient’s care. The primary wound contact material, although not always considered the most important therapeutic consideration to achieve healing, does have an extremely important effect on costs of treatment of the ulcer. This is particularly so in heavily exuding wounds managed in the community.
Since the work of Winter in 1962,3 a diverse range of modern materials have been developed with specific physical properties to facilitate healing. Many of these materials are designed to handle the exudate produced by the wound. In order to decrease the frequency of dressing changes, nurses may opt for highly absorbent dressing materials to treat such heavily exuding wounds. When exudate is not removed from the wound bed and surrounding skin, maceration can develop, adding to the management problems.4 In addition, excess exudate in chronic wounds can contain enzymes that damage both tissue and peri-wound skin.5
Alginate dressings are a popular type of modern material. They are absorbent and it has been demonstrated that they can remain on the wound bed for several days.6 A number of different brands of alginate are available and are produced in sheets of various sizes. These provide a soft, comfortable dressing that wicks laterally as the wound exudate is absorbed.
More recently a hydrocolloid fiber (hydrofiber) dressing has been developed for moderate to heavily exudating wounds in an attempt to maintain hydrocolloid properties while providing improved absorbency. This dressing is applied directly to the wound bed and produces a cohesive gel on contact with exudate. It consists entirely of sodium carboxymethylcellulose and acts by direct absorption of wound exudate into the fibers, increasing the amount of exudate that can be absorbed and reducing or eliminating lateral wicking. Further, the exudate can be retained by the dressing under compression bandaging or stocking.7 A recent review by Robinson8 has shown that hydrofiber is useful in a range of wound types and has benefits over alginates in terms of a range of performance characteristics.
In recent years, there has been a growing awareness of the costs associated with the management of chronic wounds, both in primary and secondary settings.9 Issues relating to the structure of service provision have dominated the current arguments in the costs associated with the management of chronic wounds in the community10 and it is now recognized that staff costs form a large component of the total treatment costs. However, it is also clear that factors associated with individual dressing choices can also impact greatly on total treatment costs. Dressing characteristics, such as frequency of dressing change, can impact on costs as much as traditional efficacy end-points, such as time to healing.11
The primary objective of this study was to compare the cost-effectiveness (in terms of wear time, time to healing, and reduction in ulcer size) of a hydrofiber dressing* with an alginate dressing* acting as a secondary dressing.
Procedure
In patients where clinically indicated, compression was provided using a Class 3c bandage**** over orthopedic padding. Dressing change frequency was performed according to clinical need, and dressings could be left in place for up to seven days (as per manufacturers’ instructions).
Wound assessments were undertaken on a weekly basis. Patients were followed until they healed or for a maximum of twelve weeks. If the wound became infected during the study period, the doctor caring for the patient prescribed systematic antibiotic treatment, and the patient remained in the study. If topical antimicrobial treatment was deemed more appropriate then the patient was withdrawn from the study. For those in the alginate group whose wounds became infected, the dressings had to be changed daily to comply with the manufacturer’s instruction, until the infection had resolved.
Both the investigator and patient measured the secondary outcomes. Overall ease of application and removal was assessed by the investigator report using a four-point scale ranging from ‘poor’ to ‘excellent’ on a patient-by-patient basis. A similar scale was used by the investigator to evaluate overall ability of the dressing to contain exudate. At each dressing change, the dressings were assessed for adhesion and residue on a yes/no basis. Pain on dressing removal was assessed by patient self-report on a yes/no basis.
Cost Calculations
Cost effectiveness was calculated by comparing clinical outcomes with costs as set out by the International Committee on Wound Management12 and the then current Health Economic UK Guidelines.13 Details of all materials used at each dressing change were recorded in order to calculate the average costs used in the study: an additional cost of £15 ($21.53) to reflect the nursing staff cost for each dressing change was included.14 Costs were calculated using May 2000 Drug Tariff prices per unit as shown in Table 1 (with the exception of the orthopedic wool, which was not then available on prescription).
The clinical outcomes used were healing, reduction in ulcer area, and dressing wear time both limited by the 12 weeks of the study period. These parameters were chosen to reflect the changes in wound size where total wound healing was not achieved. The total cost within each treatment group was divided by the total actual change in ulcer area (mm2) and multiplied by 100 to obtain an average cost per 1cm2 reduction. The total costs within each treatment group were divided by the total percentage change in ulcer areas and multiplied by 10 to obtain an average cost per 10-percentage point reduction in ulcer area. This was chosen to reflect the minimum level of progress to healing that might be considered relevant by a clinician.
In addition, total costs within each treatment group were divided by the total number of subjects whose ulcer had healed with quantifiable costs to obtain an average cost per healed patient.
Statistical Analysis
Data were processed on an ‘intention to treat’ basis so that all information relating to a subject who participated in the study was retained. The data were analyzed using the Statistical Package for the Social Sciences, version 7.5. Categorical data are presented in frequency tables, and continuous data are presented using summary statistics. Data comparing the two groups were analyzed using t-test or Mann Whitney U test dependent on whether the data met the distribution requirements. Chi-Square was used for dichotomous variables. Rate of healing was analyzed using Kaplan-Meier Survival analysis, with Log Rank Test to compare survival curves. All inferential analysis was performed using two-tailed testing, with alpha set at 0.05.
Results
A total of 131 subjects were recruited to this study, (hydrofiber group, 66; alginate group, 65). Baseline demographics and wound etiology of the sample are presented in Table 2. Overall more women were recruited into the study than men, with a mean age of 76.5 years for all participants. Patients were quite well matched in terms of sex, age, ulcer etiology distribution, and baseline wound characteristics.
Outcomes
Mean wear time. The mean wear time in the hydrofiber group was 3.63 days (SD, 1.8; range, 1–13 days) compared to a mean wear time of 3.27 days for the alginate group (SD, 1.9; range, 1–9). There was a statistical difference between the groups at p < 0.001 (Table 3).
Time to healing. Seventeen patients healed in each group. The Log Rank Test to compare survival curves for both groups was 0.05, indicating that there was no difference between the groups when all 131 patients were included in the analysis. The mean time to healing for those who achieved complete closure of the wound approached significance at p = 0.053, with a mean difference of 14 days in favor of the hydrofiber (mean days to healing hydrofiber, 41.82; alginate, 56.88; Table 4).
Reduction in ulcer size. Tables 5 and 6 summarize the changes in ulcer area from baseline to final assessment. There was no statistical difference in change of ulcer size between the groups (mean change hydrofiber, 516.8mm2; alginate, 347.3mm2). These three outcomes indicate evidence of a statistical difference in the efficacy of the two dressings in terms of wear time, and a trend towards differences in healing rates.
Cost-Effectiveness Data
Average cost to achieve ulcer healing. Table 7a summarizes the average cost to achieve ulcer healing by treatment group including nursing costs. Alginate was one percent less cost effective than hydrofiber in the average cost per healed subject. The average cost per healed subject on hydrofiber was £1184.09 ($1699.71) compared with £1200.73 ($1723.59) on alginate.
Average cost per 1cm2 reduction in ulcer size. Table 7b summarizes the average cost per 1cm2 reduction in ulcer area by treatment group including nursing costs. Alginate was 36-percent less cost effective than hydrofiber in the average cost per 1cm2 reduction in ulcer area. The average cost per 1cm2 reduction in ulcer area on hydrofiber was £59.22 ($85.01) compared with £92.27 ($132.46) on alginate.
Average cost per 10-percentage point reduction in ulcer size. Table 7c summarizes the average cost per 10-percentage point reduction in ulcer area by treatment group, including nursing costs. Alginate was 24-percent less cost effective than hydrofiber in the average cost per 10-percentage point reduction in ulcer area. The average cost per 10-percentage point reduction in ulcer area on hydrofiber was £80.15 ($115.06) compared with £104.92 ($150.62) on alginate.
Overall Dressing Performance
In the hydrofiber group, 76 percent recorded ‘excellent’ for overall ease of application compared with 55 percent in the alginate group (p = 0.03, 95% CI= 4–36%); 51 percent recorded ‘excellent’ for overall ease of removal compared with 24 percent in the alginate group (p = 0.006, 95% CI = 11–42%); 44 percent recorded ‘excellent’ for overall ability to contain exudate compared with 20 percent in the alginate group (p = 0.002, 95% CI = 10–41%). Thirty-eight percent of the hydrofiber dressing changes recorded some adhesion to the wound bed compared with 74 percent in the alginate group (p < 0.001), while 82 percent of dressing changes were associated with no pain for the hydrofiber group compared with 62 percent of changes for the alginate group (p < 0.001).
Discussion
Design of cost-effectiveness studies in wound care is still evolving. The use of four centers to recruit 131 patients with a range of ulcer etiologies reflects the current state of clinical practice in the United Kingdom.
The distribution of ulcer etiology has been widely reported previously1,15,16 with a predominance of elderly women presenting with venous ulceration. The sample in this study reflects the types of chronic ulcers treated in the community and gives a realistic indication of the type of care expected within the community environment.
Clinicians traditionally judge success of treatment interventions by the number of patients healed or the rate of reduction in ulcer area in a cohort of patients. This study showed no significant difference between the two wound dressings under test in these terms. This is not surprising, as no other published study of modern wound dressings has been able to achieve this in patients with chronic wounds due to the heterogeneity of the outcomes likely to occur in such patients. Although a statistical difference was found in terms of wear time, this may have limited clinical importance.
More recently, evaluation of dressing performance has been accepted as an alternate means of differentiating between materials. This study has shown a difference between the alginate and the hydrofiber in terms of ease of application and removal, ability to contain exudate, adhesions to the wound, and reduction of pain at dressing change. This differential in terms of dressing performance would be seen by many patients and clinicians involved in day-to-day care of community patients with chronic wounds as important parameters to determine the usefulness of such materials in clinical practice.
Performance outcomes, however, may not be seen as important enough by planners and policy makers in healthcare systems and for such individuals measures of cost effectiveness may be seen as the critical evidence to determine changes in policy or practice.
While recognizing the significant contribution of staff costs to the total treatment costs of managing chronic wounds in the community, dressings that have a longer wear time will have a major influence on cost by reducing the number of dressing changes required within an episode of ulceration. This study has shown a significant difference in terms of wear time in favor of the hydrofiber indicating that this new material has potential cost benefits to the National Health Service.
Measurement of treatment costs, although now feasible, are often performed as part of an evaluation of a new material; however, they may not be sufficient on their own to demonstrate true cost effectiveness as some form of acceptable outcome for success must be included to measure true cost effectiveness. As previously mentioned, complete healing is often seen as the only means of success in patients with ulceration; however, as recognized by many workers in this area, this is not always an achievable goal for all patients. Hence measures of progress towards healing, seen as partial success, may be more relevant means of determining cost effectiveness.
Using two measures of progress towards healing to demonstrate cost-effectiveness, namely in terms of 1cm2 in reduction in ulcer area and 10 percent reduction in ulcer area, this study has also shown significant benefits of using the hydrofiber over the alginate material.
In conclusion, although this study has shown no differences between the dressings in their ability to heal more wounds, significant differences in terms of dressing performance, dressing wear time, and cost effectiveness have been shown and indicate that this hydrofiber dressing will confer many benefits to the overall management of patients with chronic leg ulceration in the community setting.
*Aquacel™, ConvaTec Ltd, Ickenham, London, UK
**Sorbsan™, Maersk, North Moons Moat, Redditch, Worcs., UK
***Release, Johnson & Johnson Advanced Wound Care, A Division of Ethicon, Somerville, New Jersey, USA
****SurePress™ ConvaTec Ltd, Ickenham, London, UK
