Study Touts CF Drug Ivacaftor as Prime Example of Precision Medicine

Ivacaftor, the first drug that targeted the underlying defect of cystic fibrosis (CF), which affects about 30,000 people in the United States, improved outcomes and reduced hospitalizations, according to an analysis in the May issue of Health Affairs examining precision medicine.

CF is an incurable, life-threatening genetic disease that is caused by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which regulates the movement of ions and water in and out of cells. The mutation causes secretions to accumulate in the lungs and digestive tract, resulting in severe respiratory and digestive problems and potentially contributing to complications like diabetes or infections.

The authors used claims data to examine the role and potential of precision medicine, and said the drug “effectively treats a subpopulation of people with cystic fibrosis based on their unique genetic makeup.”

This can help providers, policy makers, and patients assess the value of treatments relative to their cost and use, they said, especially as eligibility for the drug expands by patients’ age and genetic mutation.

The drug was first approved by the FDA in 2012 and the FDA expanded the label to include additional variants in 2014 and, again, in 2017. The label expansions meant that 14% of the CF population were eligible to take the drug, which has a list price of $311,000.

Rates of hospital inpatient admissions before and during use of ivacaftor found that overall and CF-related inpatient admissions fell by 55% and 81%, respectively. Ivacaftor was also associated with 60% lower per person inpatient spending in the year following starting the drug, compared to the previous year.

The total sample included 143 people who had filled prescriptions for ivacaftor, 63% of whom were age 18 or older. The analysis builds upon previous studies by estimating all-cause and CF-related hospitalizations among patients who began treatment from February 2012 to December 2015.

Patients with CF who took ivacaftor were their own control group. The pre-ivacaftor period was the 12 months before a person’s first filled prescription, and the post-ivacaftor period was the 12 months after the first filled prescription. In the year before filling their first prescription for ivacaftor, 31% of patients had had at least 1 inpatient admission.

Overall, the rate of inpatient admissions decreased 55% from 0.57 admissions per person-year in the period before filling the first prescription to 0.26 admissions in the period after filling that prescription. Decreases were similar for children and adults (59% and 52%, respectively). The percentages of people with 1 or more admissions also decreased over time by 55% (P <.0001). There was a 61% decrease for children (P = 0.0096) and a 50% decrease for adults (P = 0.0033).

CF admissions, a subset of all-cause admissions, fell even more dramatically than all-cause admissions did. The percentages of people with 1 or more admissions with a principal diagnosis of CF decreased by 78% overall (P <.0001). Admissions with principal diagnosis codes for CF decreased 81%, from 42 before filling a prescription for ivacaftor to 8 after.

Rates per person per year decreased by 82% among children ages 6 to 17 and 80% among adults. The decreases in the percentages of people with 1 or more admissions were also similar between age groups, with declines of 80% for children and 77% for adults.

The declines in the percentages of people with 1 or more admissions were similar between the initial and expanded-label subcohorts, with declines in overall admissions of 59% and 57% and decreases in admission rates of 49% and 62%, respectively.

Patients who filled at least 10 prescriptions during the 12-month period experienced 68% pre-post reductions in inpatient admissions, compared with 45% for those with 3 to 9 fills.

Spending

Use of ivacaftor was associated with 60% lower per person inpatient spending (adjusted for medical inflation to 2016 prices) in the year after starting the drug, relative to the year before it. There was a greater proportional reduction in hospital costs for adults taking ivacaftor than for children (68% and 45%, respectively), but similar absolute differences. There was an absolute per person reduction of $10,567, from $17,729 to $7162.

The analysis was published just as the pharmaceutical industry is waiting to see what President Donald Trump will say in a speech about drug pricing; the speech has been in the works for a few weeks but delayed twice.

The authors wrote that while the drug is covered by public and private payers, they acknowledged that the cost of specialty drugs is growing and that cost concerns can lead to delays, or that costs often get passed onto patients.

The authors said their analysis of administrative claims data confirmed the association of ivacaftor with reduced hospitalizations that was first reported in clinical trial and patient registry studies.

Reference

Feng LB, Grosse SD, Green RF, et al. Precision medicine in action: the impact of ivacaftor on cystic fibrosis—related hospitalizations. Health Aff (Millwood). 2018;(37):773-779. doi: 10.1377/hlthaff.2017.1554.