|
Pharmacoeconomic impact of inhaled corticosteroids |
Stempel D A |
|
|
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 three inhaled corticosteroids (ICSs) for the treatment of persistent asthma. The ICSs were fluticasone, triamcinolone and zafirlukast.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised patients suffering from persistent asthma, as defined by the International Classification of Diseases, 9th Revision (ICD-9) code (493.XX).
Setting The setting of the study appears to have been the community. The economic study was carried out in the USA. It involved 13 United Healthcare-affiliated plans, insuring about 1.4 million lives.
Dates to which data relate The effectiveness and resource use data were gathered from October 1, 1995, to December 31, 1998. The price year was not reported.
Source of effectiveness data The effectiveness evidence was derived from a single study.
Link between effectiveness and cost data The costing was undertaken prospectively on the same patient sample as that used in the effectiveness analysis.
Study sample Power calculations to determine the sample size were not reported. Patients were selected if they were taking fluticasone, zafirlukast or triamcinolone, and enrolled in the United Healthcare-affiliated plans that were included in the study, during the study period.
In analysis 1, a sample of 1,493 patients was selected. There were 1,101 patients in the fluticasone group and 392 in the zafirlukast group. The mean age in the fluticasone group was 34.2 years (standard deviation, SD=17.1) and 41% were men. The mean age in the zafirlukast group was 39.0 years (SD=15.9) and 45% were men.
In analysis 2, a sample of 4,999 patients was selected. There were 857 patients in the fluticasone group and 4,142 in the triamcinolone group. The mean age in the fluticasone group was 32.9 years (SD=17.6) and 42% were men. The mean age in the triamcinolone group was 34.6 years (SD=17.0) and 39% were men.
Study design This was a case-control study carried out in 13 United Healthcare-affiliated plans. All patients were enrolled for at least 21 months. This period comprised 9 months before (pre-index period) and 12 months after (post-index period) the prescription of the ICS (fluticasone, triamcinolone or zafirlukast). Patients could not have a claim for an ICS or leukotriene modifier in the pre-index period, and could not use the alternative medication in the post-index period.
Analysis of effectiveness It would appear that all of the patients included in the study were accounted for in the analysis (in effect, intention to treat). The primary health outcomes measured in the analysis were emergency department visits and hospitalisations. The study groups were not perfectly comparable at baseline, for example, the zafirlukast patients tended to be older than the fluticasone patients. However, the patient demographics became similar after adjustments for age and gender.
Effectiveness results In analysis 1, fluticasone resulted in a 62% decrease in emergency department visits and a 72% decrease in hospitalisations, whilst zafirlukast led to a 32% decrease in emergency department visits and a 26% decrease in hospitalisations.
In analysis 2, fluticasone resulted in a 59% decrease in emergency department visits and a 64% decrease in hospitalisations, whilst triamcinolone led to a 38% decrease in emergency department visits and a 29% decrease in hospitalisations.
All the differences reached statistical significance.
Clinical conclusions The effectiveness analysis showed that fluticasone was more effective than either zafirlukast or triamcinolone in reducing hospitalisations and visits to the emergency department.
Modelling A decision tree was constructed for the selection of the first-line therapy for persistent asthma. Details of the model were not reported.
Measure of benefits used in the economic analysis The health outcomes were left disaggregated and no summary benefit measure was used. A cost-consequences analysis was therefore carried out.
Direct costs Discounting was irrelevant since costs were incurred over less than two years. The unit costs and the quantities of resources were not reported separately. The cost/resource boundary was that of the managed health organisation. The health costs included in the analysis were hospitalisation, emergency department visits, physician office visits, outpatient visits, and pharmacy claims. The costs and the resources used were estimated using actual data derived from administrative claims of United Healthcare data. The resources were collected from October 1, 1995, to December 31, 1998. No price year was reported.
Statistical analysis of costs Statistical analyses were carried out on the total costs to determine the statistical significance of the results. In addition, the monthly costs were adjusted for factors such as age, gender, pre-index health costs, asthma costs and co-morbid respiratory conditions.
Indirect Costs The indirect costs were not included.
Sensitivity analysis Sensitivity analyses were not conducted.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results In analysis 1, the asthma care costs were $59.53 per member per month (PMPM) in the pre-index period and $46.33 in the post-index period with fluticasone. The corresponding costs with zafirlukast were $63.43 PMPM in the pre-index period and $76.82 in the post-index period. Consequently, the asthma care costs decreased by $13 PMPM (-22%) with fluticasone and increased by $13 PMPM (+21%) with zafirlukast. This difference was statistically significant.
The total health care costs diminished from $334.40 to $312.93 with fluticasone (-$21.47, -6%) and increased from $306.07 to $380.18 (+$74.11, +24%) with zafirlukast.
In analysis 2, the asthma care costs decreased 21% (-$126 yearly) for patients treated with fluticasone and 10% (-$47 yearly) for patients treated with triamcinolone.
The total health care costs were reduced by 9% (-$324 yearly) with fluticasone and were increased by 13% (+$375 yearly) with triamcinolone, although the acquisition costs were statistically higher for fluticasone.
Synthesis of costs and benefits Authors' conclusions Fluticasone was more effective than zafirlukast and triamcinolone for the treatment of persistent asthma. The use of fluticasone for one year was also associated with substantial cost-savings.
CRD COMMENTARY - Selection of comparators The rationale for the choice of the comparator was clear. Zafirlukast and triamcinolone were selected as they represented alternative ICSs available for the treatment of persistent asthma. You should assess whether they represent currently used treatments in your own setting.
Validity of estimate of measure of effectiveness The analysis of effectiveness used a case-control study, which appears to have been appropriate for comparing the therapies under examination. Power calculations were not performed, but the sample size was large. The author acknowledges that, due to the lack of randomisation, selection bias could not be excluded since only patients taking fluticasone, zafirlukast or triamcinolone were selected. Statistical analyses were carried out to take into account differences among the study groups, which were not perfectly matched at baseline, although adjustments were made to address this limitation.
Validity of estimate of measure of benefit No summary benefit measure was used in the economic analysis. The outcomes assessed in the effectiveness analysis reflected more the resources used than the impact of the therapies on the patients' health.
Validity of estimate of costs The analysis of costs was carried out from the perspective of the managed health organisation. It appears that all of the relevant categories of costs have been included in the analysis. Statistical analyses of the costs were carried out. However, the price year was not reported, and the unit costs and the quantities of resources were not reported separately, thus limiting the generalisability of the results. It would have been interesting had the author assessed the impact of the indirect costs on the analysis.
Other issues The author made several comparisons of his findings with those from other studies. However, the issue of the generalisability of the study results to other settings was not addressed. Therefore, the external validity of the study may be limited. The study enrolled patients suffering from persistent asthma and this was reflected in the author's conclusions.
Implications of the study The author suggests the adoption of ICSs, in particular fluticasone, as first-line therapy for the treatment of persistent asthma. The results of the study, carried out in a real-world setting, appear to confirm the findings obtained in clinical trials that have generally been conducted over a shorter period of time.
Bibliographic details Stempel D A. Pharmacoeconomic impact of inhaled corticosteroids. American Journal of Managed Care 2000; 6(7 Supplement S): S382-S387 Indexing Status Subject indexing assigned by CRD MeSH Administration, Inhalation; Androstadienes /administration & Asthma /drug therapy /economics; Cost-Benefit Analysis; Leukotriene Antagonists /administration & Triamcinolone /administration & dosage /economics; dosage /economics; dosage /economics AccessionNumber 22000000891 Date bibliographic record published 31/12/2002 Date abstract record published 31/12/2002 |
|
|
|