C ystic fibrosis is the most common fatal inherited disor- der in the US, 1 occurring approximately once in every 3400 live births of white infants. 2 Although multisystemic, cystic fibrosis is characterized primarily by an accumula- tion of thick mucus in the lungs, which limits pulmonary function and often leads to recurrent or persistent respirato- ry tract infections. Approximately one-third of patients with cystic fibrosis are hospitalized annually 3 ; >75% of these admissions are the result of respiratory tract infections. 4 The cost per admission has been estimated to range from $7000 to $25 000. 4-7 The highly viscous nature of mucus in the lungs of pa- tients with cystic fibrosis is due in large part to a high DNA concentration. rhDNase is a recombinant form of human deoxyribonuclease I (DNase) that has been shown to re- duce the viscosity of cystic fibrosis sputum. 8 In a Phase III multicenter clinical trial, 9 in which 968 cystic fibrosis pa- tients were randomized to receive one of two doses of rh- DNase or placebo, forced expiratory volume was found to be approximately 6% higher among patients receiving rhDNase on average over 24 weeks compared with base- line; no improvement was noted in the placebo group (p < 0.001). The incidence of respiratory tract infections was approximately 25% lower among patients randomized to receive rhDNase. This trial 9 also provided preliminary evidence of the economic benefits of rhDNase therapy; estimated costs of respiratory-related inpatient care over 24 weeks (excluding the cost of rhDNase) were $814–$1682 lower among pa- tients receiving rhDNase compared with patients receiving placebo. 10 Under conditions of typical clinical practice, however, where compliance with rhDNase therapy may be less than optimal, the magnitude of economic benefits is unknown. We undertook a retrospective cohort study using healthcare claims data from a large New England health insurer to explore this issue. Use of rhDNase Therapy and Costs of Respiratory-Related Care in Patients with Cystic Fibrosis Daniel A Ollendorf, Lisa J McGarry, Marc L Watrous, and Gerry Oster Pharmacoeconomics Author information provided at the end of the text. OBJECTIVE: To assess the relationship between level of use of recombinant deoxyribonuclease I (rhDNase) therapy and costs of respiratory-related care in patients with cystic fibrosis. DESIGN: Retrospective, cohort study using healthcare claims data from a large New England health insurer. PATIENTS: All cystic fibrosis patients five years of age and older who began therapy with rhDNase in 1994 (the year it was first marketed in the US). Healthcare claims were compiled for six months prior to first receipt of rhDNase (pretreatment) and for 30 months subsequently (follow-up). Patients were stratified according to their level of rhDNase use during follow-up, based on whether it was above or below the median number of therapy days for the sample. MAIN OUTCOME MEASURES: Costs of rhDNase, all antibiotics, and all respiratory-related outpatient (physician, home health, hospital outpatient) and inpatient care were included. All costs were expressed on an annualized basis. RESULTS: Twenty-four patients with cystic fibrosis who began treatment with rhDNase in 1994 met all entry criteria; the median number of therapy days over a 30-month period was 355. Among patients with low (i.e., below the median) rhDNase use (n = 12), mean ± SD annualized costs of respiratory-related care increased by almost $17000 between pretreatment and follow-up, from $29251 ± $37919 to $46109 ± $40944. Among high-use patients (n = 12), costs decreased by approximately $2500, from $37 178 ± $48476 to $34592 ± $22591. The change in both groups was accounted for primarily by a change in the number of respiratory- related hospitalizations. CONCLUSIONS: Prolonged use of rhDNase may reduce costs of respiratory-related care in patients with cystic fibrosis; further study is required, however, to confirm these findings. KEY WORDS: rhDNase, cystic fibrosis, costs-and-cost-analysis. Ann Pharmacother 2000;34:304-8. at Fund Diag.Est Imstico PARENT on October 11, 2013 aop.sagepub.com Downloaded from at Fund Diag.Est Imstico PARENT on October 11, 2013 aop.sagepub.com Downloaded from at Fund Diag.Est Imstico PARENT on October 11, 2013 aop.sagepub.com Downloaded from at Fund Diag.Est Imstico PARENT on October 11, 2013 aop.sagepub.com Downloaded from at Fund Diag.Est Imstico PARENT on October 11, 2013 aop.sagepub.com Downloaded from