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Cost, efficacy, efficiency and tolerability of collagenase ointment versus hydrocolloid occlusive dressing in the treatment of pressure ulcers: a comparative, randomised, multicentre study |
Burgos A, Gimenez J, Moreno E, Lamberto E, Utrera M, Urraca E M, Velez F J, Lopez E, Martinez M A, Gomez M J, Garcia L |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Collagenase ointment applied once daily in a 1 to 2mm thick layer to the ulcer bed, or hydrocolloid occlusive dressing changed every 3 days in the treatment of patients with pressure ulcer.
Economic study type Cost-effectiveness analysis.
Study population Patients aged over 55 years having had stage III pressure ulcers (characterised by skin disruption, tissue damage and exudate, and subcutaneous cell tissue involvement) for less than 1 year. Patients were excluded from the study if they had end-stage organ disease, localised or systemic signs and/or symptoms of infection (fever, local erythema, regional lymph node swelling) or hypersensitivity to collagenase.
Setting Hospital. The economic analysis was carried out in Spain.
Dates to which data relate The dates corresponding to the collection of effectiveness and resource use data were not given. The price year was 1998.
Source of effectiveness data The evidence for the final outcomes was based on a single study.
Link between effectiveness and cost data Costing was conducted on the same patient sample as that used in the effectiveness analysis and appears to have been performed prospectively.
Study sample Power calculations were not used to determine the sample size. The study sample consisted of 37 evaluable patients; of whom 18 were in the collagenase group with a mean (SD) age of 81.9 (12.7) years and 19 in the hydrocolloid group with a mean (SD) age of 78.6 (10.4) years. Of the initially recruited patients, 6 were excluded from the study for reasons such as death from unrelated causes (n=1), discharge from the hospital (n=1) and protocol violation (n=4).
Study design This was a multicentre, randomised, non-blind, parallel group study, carried out in 7 centres. Treatment was continued for 12 weeks or until complete healing of the ulcer; whichever occurred first. The duration of the follow-up was 1 year. Apart from 4 patients who were excluded because of protocol violation, 8 (44.4%) patients in the collagenase group and 6 (31.6%) patients in the hydrocolloid group, discontinued the study prematurely; the relative risk of discontinuing the study for any reason was not significantly different between either group. Patients who discontinued hydrocolloid improved significantly less than patients who discontinued collagenase, and patients who discontinued hydrocolloid improved significantly less than hydrocolloid patients who completed study treatment. Patients were randomised, using a computer-generated randomisation list, into blocks of four patients. Clinical history and physical examination, as well as Arnell scale score were obtained from all patients. Blood samples and exudate samples were taken for haematological and biochemical, and microbiological studies.
Analysis of effectiveness The principle used in the analysis of effectiveness was claimed to be both intention-to-treat and treatment completers only (per-protocol analysis). The primary health outcome was reduction of ulcer area assessed at 1-week intervals. Pain, granulation tissue, exudate and odour were also evaluated, as were nutrition state and occurrence of adverse reactions. Examinations were made at 1-week intervals and consisted of a photograph of the ulcer, assessment of the ulcer area, evaluation of four ulcer characteristics, and adverse reactions. Ulcer characteristics were measured on a 5-point scale and included pain (no pain = 1, up to unbearable = 5), percentage of granulation tissue (less than 1%, up to greater than 90% = 5), exudate (no exudate = 1, up to excessive = 5), odour (no odour = 1, up to repulsive = 5). To assess reliability of ulcer area measurements, absolute differences in mean ulcer area between transparent acetate film (direct) and slide (indirect) measurements at baseline and at the end of the study were calculated. The study groups were comparable in terms of baseline demographic and clinical characteristic.
Effectiveness results The effectiveness results were as follows:
Ulcers healed completely in six patients (three in each treatment group, (p=0.451)).
Ulcer area decreased in 83.3% of the collagenase-treated group and in 73.7% of the hydrocolloid-treated patients, (p=0.754), after 12 weeks of treatment.
The mean (SD) reduction in ulcer area in the collagenase group was 9.1 (1.2) square-cm and 6.2 (9.8) square-cm in the hydrocolloid group; an ulcer area reduction of 44.2% and 27.9%, respectively.
Analysis of the ulcer characteristics showed a statistically significant pain intensity decrease in the collagenase group (p=0.001).
Granulation tissue formation increased (p<0.0005) and exudate production decreased (p<0.0005) in both treatment groups.
Odour was not modified throughout the study period; in most patients it was absent at randomisation and did not surpass the category of 'bearable' at any stage.
Bacterial colonisation was present in 32 (91.4%) of the 35 patients in whom microbiological cultures of ulcer exudate were carried out at the beginning of the study, i.e. 15 (93.8%) of 16 in the collagenase group and 17 (89.5%) of 19 in the hydrocolloid group, (NS).
The tolerability of both study treatments was good.
Adverse reactions were mild and did not cause discontinuation of the study treatment. The relative risk of adverse reaction occurrence was 0.5 (95% CI: 0.041-6.048).
In the present study, most patients (77.8%) had malnutrition, a widely recognised poor prognosis factor related to pressure ulcer development.
Ulcer area measurements were validated.
Clinical conclusions These findings indicate that collagenase ointment and hydrocolloid dressing produced similar healing effects in patients with pressure ulcer.
Measure of benefits used in the economic analysis The measure of benefit was reduction in the ulcer area by 1 square-cm.
Direct costs Costs were not discounted due to the short time frame of the cost analysis. Some quantities were reported separately from the costs. Some cost items were reported separately. Cost analysis covered the costs of the study products, ancillary supplies and labour costs of nursing staff. The perspective adopted in the cost analysis was not explicitly reported. The nursing staff time was based on the actual amount of time, in minutes, required to perform the procedure. The price year was 1998.
Statistical analysis of costs Cost analyses by intention-to-treat and per protocol were carried out using Student's t test. The mean cost per patient and 95% confidence interval (CI) were also calculated.
Currency Spanish pesetas (Pta). The conversion rate was US$1 = Pta165.
Estimated benefits used in the economic analysis The mean (SD) reduction in ulcer area in the collagenase group was 9.1 (1.2) square-cm and 6.2 (9.8) square-cm in the hydrocolloid group; an ulcer area reduction of 44.2% and 27.9%, respectively.
Cost results The total cost per patient was Pta41,488 (95% CI: Pta26,191 - Pta56,784) in the collagenase group versus Pta32,963 (95% CI: Pta23,389 - Pta42,538) in the hydrocolloid group, (NS). Differences in cost distribution regarding pharmaceutical, ancillary supply and staff expenditures between both treatment groups were statistically significant (p<0.0001).
Synthesis of costs and benefits Mean global cost incurred to reduce ulcer area by 1 square-cm was calculated as the measure of cost-effectiveness ratio, resulting in a value of Pta4,559 in the collagenase group versus Pta5,310 in the hydrocolloid group. The corresponding values, when only the pharmaceutical costs were considered, were Pta2,290 in the collagenase group and Pta3,382 in the hydrocolloid group. The differences were non-significant.
Authors' conclusions No statistically significant differences in cost, efficacy or efficiency were detected between collagenase ointment and hydrocolloid dressing in the treatment of pressure ulcers, although a trend for better efficacy and efficiency of collagenase treatment was observed. The tolerability of both therapeutic regimens was good.
CRD COMMENTARY - Selection of comparators No specific health technology was regarded as the comparator since at the time of the study, both techniques were generally used in Spain for the treatment of pressure ulcers. You, as a database user, should consider which health technology is used widely in your own setting.
Validity of estimate of measure of effectiveness The internal validity of the effectiveness results cannot be guaranteed due to the relatively small sample size (power calculations not being performed to justify the sample size), and the effectiveness analysis being performed on the principle of treatment completers only (per-protocol analysis). (The authors reported that they had also performed intention-to-treat analysis, however this does not appear to be justified due to the exclusion of at least four patients from the original sample due to protocol violation). The study groups were comparable in terms of baseline demographic and clinical characteristic. The effects of different study sites (in this study 7 sites were involved) were not investigated. The dates during which effectiveness data were collected were not specified. The study sample appears to have been representative of the study population.
Validity of estimate of measure of benefit Estimation of benefits was obtained directly from the effectiveness analysis. This choice of estimate is valid but was not justified.
Validity of estimate of costs Good features of the analysis were that some quantities were reported separately from the costs; adequate details of methods of cost estimation were given; the price year was reported; all the relevant direct cost components appear to have been included in the cost analysis; and statistical analyses were performed on some resource consumption and cost data. However, the perspective adopted in the cost analysis was not explicitly reported; the effects of alternative procedures on indirect costs were not addressed; and cost results may not be generalisable outside the study setting.
Other issues The authors' conclusions appear to be justified within the limitations outlined above. The issue of generalisability to other settings or countries was not addressed, although some comparisons were made with other studies. The study sample appears to have been representative of the study population, however this was not discussed in the paper.
Implications of the study The authors consider that the present study will help decision-making bodies who are responsible for assigning available resources to choose between these treatment modalities.
Source of funding Supported by Laboratorios Knoll, SA, Madrid.
Bibliographic details Burgos A, Gimenez J, Moreno E, Lamberto E, Utrera M, Urraca E M, Velez F J, Lopez E, Martinez M A, Gomez M J, Garcia L. Cost, efficacy, efficiency and tolerability of collagenase ointment versus hydrocolloid occlusive dressing in the treatment of pressure ulcers: a comparative, randomised, multicentre study. Clinical Drug Investigation 2000; 19(5): 357-365 Indexing Status Subject indexing assigned by CRD MeSH Adult; Collagenases /therapeutic use /drug effects /economics; Colloids; Costs and Cost Analysis; Drug Tolerance; Exudates and Transudates; Granulation Tissue; Humans; Male; Ointment Bases /pharmacology; Pain; Pressure Ulcer /drug therapy /therapy; Wound Healing AccessionNumber 22000001006 Date bibliographic record published 28/02/2001 Date abstract record published 28/02/2001 |
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