Efficacy of N-acetylcysteine plus pirfenidone in the treatment of idiopathic pulmonary fibrosis: a systematic review and meta-analysis

BACKGROUND: Numerous studies have demonstrated the potential of pirfenidone to enhance the prognosis of patients afflicted with idiopathic pulmonary fibrosis (IPF). Although N-acetylcysteine (NAC) is utilized as an antioxidant in IPF treatment, the combination of NAC and pirfenidone has produced inconsistent outcomes in certain studies. To assess the clinical effectiveness and safety of NAC plus pirfenidone (designated as the treatment group) versus pirfenidone monotherapy (designated as the control group), we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs). METHODS: RCTs of NAC plus pirfenidone were reviewed searching from databases and networks of unpublished and published studies in any language. Using pair-wise meta-analysis, changes in pulmonary function test (PFT) parameters and safety were evaluated. RESULTS: Two independent reviewers selected and obtained data from 5 RCTs (n = 398), comprising 1 study from Japan, 1 from Europe, and 3 from China. NAS plus pirfenidone as compared to pirfenidone monotherapy for IPF may not reduce the incidence of skin effects(RR 1.26 [95%CI 0.64 to 2.45]) and mortality(RR 0.35 [95%CI 0.07 to 1.68])(both moderate certainty). NAS plus pirfenidone as compared to pirfenidone monotherapy for IPF may not reduce the incidence of at least one side effects(RR 1.00 [95%CI 0.84 to 1.19]; low certainty),severe side effects(RR 0.67 [95%CI 0.30 to 1.47]; low certainty) and gastrointestinal effects(RR 0.67 [95%CI 0.41 to 1.09]; low certainty) with possibly no effect in Δ%DLco(SMD -0.17 [95%CI -0.15 to 0.48]; low certainty). Meanwhile, the effect of NAS plus pirfenidone as compared to pirfenidone monotherapy on ΔFVC(SMD 0.18 [95%CI -0.68 to 1.05]), Δ%FVC(SMD -2.62 [95%CI -5.82 to 0.59]) and Δ6MWT(SMD -0.35 [95%CI -0.98 to 0.28]) is uncertain(extremely low certainty). CONCLUSION: Moderate certainty evidence suggests that NAS plus pirfenidone, compared to pirfenidone monotherapy for IPF, does not reduce the incidence of skin effects and mortality. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12890-023-02778-w.