Clinical Question: Does interferon gamma-1b (Actimmune) reduce mortality in patients with idiopathic pulmonary fibrosis?

Setting: Outpatient (specialty)

Study Design: Meta-analysis (randomized controlled trials)

Allocation: Uncertain

Synopsis: There is no clearly effective treatment for idiopathic pulmonary fibrosis. Although interferon gamma-1b, which interferes with fibroblast proliferation and modulates the inflammatory response, has been proposed, study results are mixed. The authors did a careful search and identified four randomized controlled trials in the literature but had to exclude one because it did not provide survival data in a usable form (only one death occurred in that study, so its exclusion is unlikely to affect the findings of the meta-analysis). The remaining three studies had 18, 42, and 330 patients; monitored patients for five, 1.5, and 1.4 years; and had a total of nine, eight, and 44 deaths, respectively. Each study found a reduction in mortality with interferon gamma-1b, but this reduction was not statistically significant for any individual trial. The pooled hazard ratio was 0.42 (95% confidence interval, 0.25 to 0.69), consistent with a 58 percent relative risk reduction in mortality. The pooled difference in the percentage of patients surviving at different times between treatment and control groups also was calculated: 0.5 percent at six months, 8.6 percent at one year, 16.8 percent at 18 months, and 26.5 percent at two years. All differences except the first were statistically significant.

Bottom Line: Interferon gamma-1b appears to reduce mortality in patients with idiopathic pulmonary fibrosis. Because it is associated with significant side effects, inconvenience, and cost, it may not be appropriate for all patients with idiopathic pulmonary fibrosis. (Level of Evidence: 1a)