The effectiveness and cost-effectiveness of treatments for idiopathic pulmonary fibrosis: systematic review, network meta-analysis and health economic evaluation

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is a life-limiting lung disease with considerable impact on patients and carers as the disease progresses. Currently few treatments are available. We aimed to evaluate the clinical and cost-effectiveness of available treatments for IPF.

Methods: Systematic reviews of clinical effectiveness, quality of life and cost effectiveness were undertaken. Eleven bibliographic databases were searched from inception to July 2013 and studies were assessed for eligibility against a set of pre-defined criteria. Two reviewers screened references, extracted data from included studies and appraised their quality. An advisory group was consulted about the choice of interventions. A narrative review was undertaken and where feasible fixed effect and random effects meta-analysis were undertaken including a network meta-analysis (NMA). A decision-analytic Markov model was developed to estimate cost-effectiveness of pharmacological treatments for IPF. Following best practice recommendations, the model perspective was of the national health service and personal social services, a discount rate of 3.5% for costs and health benefits was applied and outcomes were expressed as cost per quality adjusted life-year gained. Parameter values were obtained from the NMA and systematic reviews. Sensitivity analyses were undertaken.

Results: Fourteen studies were included in the review of clinical effectiveness, of which one evaluated azathioprine, three N-acetylcysteine [NAC] (alone or in combination), four pirfenidone, one nintedanib, one sildenafil, one thalidomide, two pulmonary rehabilitation, and one a disease management programme. Study quality was generally good. Evidence suggests that some effective treatments are available. In NMA only nintedanib and pirfenidone show statistically significant improvements. The model results show increased survival for five pharmacological treatments (NAC triple therapy, inhaled NAC, nintedanib, pirfenidone, and sildenafil) compared with best supportive care, at increased cost. Only inhaled NAC was cost-effective at current willingness to pay thresholds but it may not be clinically effective.

Conclusions: Few interventions have any statistically significant effect and the cost-effectiveness of treatments is uncertain. A lack of studies on palliative care approaches was identified and there is a need for further research into pulmonary rehabilitation and thalidomide in particular. A well conducted RCT on inhaled NAC therapy should also be considered.

Figure 1

Flow chart for the identification of studies in the clinical effectiveness review. ^a Two RCTs were reported in one publication; two further trials each had two linked publications. ^b One trial was published as a protocol only.

Figure 2

Evidence network for FVC endpoint. Legend: The width of the lines connecting treatment pairs is proportional to the number of participants within each trial comparison.