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Conversion de la terapia intensiva con insulina rapida a insulina lispro en la diabetes tipo 1: analisis farmacoeconomico de coste-efectividad [Conversion of fast insulin intensive therapy to lispro insulin in type I diabetes: pharmacoeconomic analysis of cost-effectiveness] |
Costa Pinel B, Belmonte Serrano M, Paez Vives F, Sabate Obiol A, Estopa Sanchez A, Borras Borras J |
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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 The use of intensive insulin treatment with lispro (lysine and proline) in Type 1 diabetes patients. Two therapeutic regimes were studied:
lispro alone before meals (breakfast, lunch and dinner), then a dose of neutral protamine hagedorn (NPH) insulin before sleeping (L1); or
a combination of lispro (80 - 85%) and NPH insulin (15 - 20%) before meals (breakfast, lunch, and dinner), then a dose of NPH insulin before sleeping (L2).
Economic study type Cost-effectiveness analysis.
Study population The study population comprised Type 1 diabetes patients aged at least 18 years, who had been on insulin therapy for at least one year (basal values of insulin C-peptide of less than 0.3 nM), and had been diagnosed as diabetic for at least 2 years. Patients under other treatments were excluded.
Setting The setting was primary care. The economic study was carried out in Tarragona, Catalunia, Spain.
Dates to which data relate The dates to which the effectiveness and resource use data corresponded were not reported. The price year was 1998.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was conducted retrospectively on the same sample of patients as that used in the effectiveness analysis.
Study sample Patients followed in the diabetes unit of the study hospital were included in the study. The study period lasted 9 months. In the base 3-month period, all the patients were using their conventional approach. In the second 3-month period, the study group was divided into two groups (L1 or L2). In the last 3-month period, crossover took place and the patients switched to the alternative treatment group. Power calculations to determine the sample size were not performed. The initial sample comprised 37 patients, of which 7 were excluded for either leaving the study (7 patients) or violating the study protocol (4 patients). Thus, a final sample of 30 patients (18 men and 12 women) was included in the analysis. The mean age of the patients was 31.8 (+/- 11.5) years, the average time to first diabetes diagnosis was 9.2 (+/- 7.1) years, and the intensive therapy lasted for an average of 5.3 (+/- 3.1) years.
Study design This was an open, crossover, randomised controlled trial. The number of sites where the study was conducted was not stated. The method of randomisation was not reported. The duration of follow-up was 9 months and 7 patients were lost-to follow-up (see 'Study Sample' field). The patients were assessed during eight protocol visits: at patient selection, at inclusion in the study, and two visits during each of the three study periods.
Analysis of effectiveness The basis of the clinical analysis was treatment completers only. The main outcome measures were a reduction in haemoglobin A1c (HbA1c), basal, preprandial, and postprandial glycaemic values, and the difference between postprandial and preprandial glycaemic values. The secondary health outcomes were variables related to insulin dosage. For example, patient weight, body mass index, dose of rapid insulin, dose of retarded insulin, total prescribed insulin dose, and dose per kilogram. The safety profile of the treatments was also analysed, assessing light (managed by the patient) and severe hypoglycaemic crises that requiring hospital admission or help by a caregiver. The comparability of the study groups was not reported.
Effectiveness results The basal glycaemic values were 144.7 (+/- 36.1) mg/dL in the basal period, 142.7 (+/- 30.6) mg/dL in the L1 period, and 135.3 (+/- 31.3) mg/dL in the L2 period.
The corresponding preprandial glycaemic values were 138.4 (+/- 26.8) mg/dL (basal), 141.8 (+/- 29.8) mg/dL (L1), and 135.1 (+/- 26.5) mg/dL (L2).
The corresponding postprandial glycaemic values were 174.7 (+/- 36) mg/dL (basal), 151.8 (+/- 29.4) mg/dL (L1), and 151.5 (+/- 34.6) mg/dL (L2).
The differences between postprandial and preprandial glycaemic values were 36.2 (+/- 26.9) mg/dL in the basal period, 10.1 (+/- 31.2) mg/dL in the L1 period, and 16.5 (+/- 32.2) mg/dL in the L2 period.
Among all these variables, only the difference in terms of postprandial glycaemic values and the difference between postprandial and preprandial glycaemic values were statistically significant.
The reduction in HbA1c values was 7.6% (+/- 1.1) in the basal period, 7.2% (+/- 1.3) in the L1 period, and 7.1% (+/- 1.4) in the L2 period. The difference was statistically significant.
There were few episodes of hypoglycaemic crisis. Only nocturnal crises were significantly different between the study periods. These were less frequent in the L1 and L2 groups than in the base period.
In terms of the variables associated with insulin dosage, there were no statistically significant differences for patient weight and body mass index. The prescribed insulin dose was lower in the base period than in the L1 and L2 periods.
Clinical conclusions The two regimens of lispro insulin proved to be safe options for patients with Type 1 diabetes. They led to significant reductions in HbA1c values and minor postprandial glycaemic values, compared with the conventional treatment using rapid insulin.
Measure of benefits used in the economic analysis The reduction in HbA1c values was used as the benefit measure. This was derived from the effectiveness analysis.
Direct costs The costs included in the analysis were for the insulin and injections. The unit costs were not reported separately from the quantities of resources. The cost/resource boundary adopted in the study was not stated. The costs were estimated from Spanish retail prices. The resource use was estimated using data derived from the trial. No discounting was performed since the costs were incurred over nine months. The price year was 1998.
Statistical analysis of costs No statistical analysis of the costs was conducted.
Indirect Costs The indirect costs were not included.
Sensitivity analysis No sensitivity analysis was conducted.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results The total daily cost was Pta 195.4 (+/- 64.2) in the base period, Pta 251.1 (+/- 91) in the L1 period, and Pta 224.6 (+/- 79.8) in the L2 period.
The total cost per injection was Pta 53.6 (+/- 19) in the base period, Pta 68.4 (+/- 25.5) in the L1 period, and Pta 61.6 (+/- 24) in the L2 period.
All these differences were statistically significant.
Synthesis of costs and benefits An incremental cost-effectiveness analysis was conducted to combine the costs and the benefits of the interventions. Compared with the base period, the extra daily cost required to produce a 1% reduction in HbA1c values was Pta 134.1 for L1 and Pta 53.7 for L2.
Authors' conclusions Lispro insulin therapy cost more than the standard insulin treatment, but the extra cost required to obtain a reduction in HbA1c values appears to have been acceptable for a new intervention. Both lispro insulin regimes were cost-effective in comparison with the conventional treatment using rapid insulin.
CRD COMMENTARY - Selection of comparators The treatment based on rapid insulin using multiple injections, combined with NPH before sleeping, was selected as the comparator since it represented the conventional treatment for patients with Type 1 diabetes.
Validity of estimate of measure of effectiveness The internal validity of the analysis was high as the study used a randomised controlled trial. The study sample appears to have been representative of the study population. However, the analysis was conducted on the basis of treatment completers only and power calculations were not performed. No evidence was provided that the initial sample was adequate for the study question. The method of randomisation was not reported. The authors discussed the fact that no blinded assessment was conducted due to objective problems (use of injections). These issues may have limited the internal validity of the analysis, as the sample size was fairly small.
Validity of estimate of measure of benefit The benefit measure was an intermediate outcome measure derived from the effectiveness analysis.
Validity of estimate of costs The perspective adopted in the study was not reported. Only the costs strictly related to insulin administration (drug use and injections) were included in the analysis. The unit costs and the quantities of resources used were not reported separately. No statistical analyses of the costs were conducted. The source of the data on the costs and resource use was reported. The price year was given, thus facilitating reflation exercises in other settings.
Other issues The authors made some comparisons of their findings with those from other studies. However, they did not address the issue of the generalisability of the study results to other settings. For this reason, and also because sensitivity analyses were not conducted, the external validity of the analysis was fairly low. The study enrolled a sample of patients with Type 2 diabetes and this was reflected in the conclusions of the analysis.
Implications of the study Lispro insulin proved to be a cost-effective intervention in patients suffering from Type 1 diabetes. The authors suggested that further studies should rely on long-term effectiveness data and a large sample of patients.
Source of funding Financed in part by Bayer Diagnostics (Spain).
Bibliographic details Costa Pinel B, Belmonte Serrano M, Paez Vives F, Sabate Obiol A, Estopa Sanchez A, Borras Borras J. Conversion de la terapia intensiva con insulina rapida a insulina lispro en la diabetes tipo 1: analisis farmacoeconomico de coste-efectividad. [Conversion of fast insulin intensive therapy to lispro insulin in type I diabetes: pharmacoeconomic analysis of cost-effectiveness] Revista Clinica Espanola 2001; 201(8): 448-454 Indexing Status Subject indexing assigned by NLM MeSH Adult; Cost-Benefit Analysis; Cross-Over Studies; Diabetes Mellitus, Type 1 /drug therapy; Economics, Pharmaceutical; Female; Humans; Hypoglycemic Agents /economics /therapeutic use; Insulin /analogs & Insulin Lispro; Male; derivatives /economics /therapeutic use AccessionNumber 22002006385 Date bibliographic record published 31/05/2003 Date abstract record published 31/05/2003 |
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