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.

RhDNase for treating respiratory-tract infections in patients with cystic fibrosis.

Treatment

Cost effectiveness analysis.

968 patients took part in a clinical study in the USA over 24 weeks. The patients were at least 5 years old.

Patients were recruited from 51 institutions in the USA.

Effectiveness and resource data were obtained from Fuchs (1994). Prices related to 1993.

Single study.

Resource data was taken from Fuchs (1994), costings were then added in this paper and an analysis performed.

Patients were randomly assigned to one of 3 treatment regimes:

2.5 mg of rhDNase once a day;

2.5 mg of rhDNase twice daily; or

placebo for 24 weeks.

Power calculations determined the sample size. Clear inclusion criteria was stated.

Multi-centre, randomised, double-blind, placebo-controlled study with follow-up lasting 24 weeks.

The main outcomes were pulmonary function and respiratory exacerbations. The treatment groups were clinically comparable at enrolment, except for age. There was a 3% drop-out rate, reported to be evenly distributed between the groups.

As compared with placebo, the administration of rhDNase once daily and twice daily reduced the age-adjusted risk of respiratory exacerbations by 28% (p= 0.04) and 37% (p< 0.01) respectively. Also the once daily and twice daily routines improved force expiratory volume in one second during the study by a mean of 5.8 percent (+/- 0.7) and 5.6 percent (+/- 0.7) respectively.

The administration of rhDNase reduced (but did not eliminate) exacerbations of respiratory symptoms, resulted in a slight improvement in pulmonary function and was well tolerated.

The main outcomes were pulmonary function and respiratory exacerbations.

Costs and quantities were reported separately. Costs per hospital day were obtained from 3 cystic fibrosis centres. The use of resources between the two groups was tested using the Wilcoxon rank sum test. The cost of the rhDNase medication itself was excluded as was the cost of parenteral support.

Quantities were analysed using the Wilcoxin rank sum test.

German marks (DM)

Costs were subjected to a one-way simple sensitivity test.

As compared with placebo, the administration of rhDNase once daily and twice daily reduced the age-adjusted risk of respiratory exacerbations by 28% (p= 0.04) and 37% (p< 0.01) respectively. Also the once daily and twice daily routines improved force expiratory volume in one second during the study by a mean of 5.8% (+/- 0.7) and 5.6% (+/- 0.7) respectively.

Cost analysis for patients in the rhDNase group in comparison to the placebo group was as follows:

net hospital cost: DM2324 rhDNase, DM3035 placebo;

cost per ambulatory treatment: DM602 rhDNase, DM602 placebo;

cost of antibiotics: DM2954 rhDNase, DM4213 placebo;

direct total cost: DM5879 rhDNase, DM7849 placebo.

RhDNase seemed to be the dominant strategy.

The use of rhDNase itself led to a reduction in the cost of treating patients (excluding the costs of the drug itself).

The separation of quantity and cost data was useful as it allows planners to attach costs in their own areas. However, there was unfortunately no attempt to link costs with effectiveness and the cost of the drug itself was a large omission.

None indicated

Fuchs H J et al. Effect of aerosolized recombinant human DNase on exacerbations of respiratory symptoms and on pulmonary function in patients with cystic fibrosis. NEJM 1994;331(10):637-642.