Table 3.

Summary of trials of pharmacological therapy in IPF-related cough.

References	Study design	Number of participants	Intervention	Primary endpoint
Birring et al. (81)	Multi-center randomized double-blind placebo-controlled crossover trial	24	Nebulised sodium cromoglycate (PA101) via nebuliser 40 mg tds for 14 days	Mean reduction in daytime objective cough frequency (coughs per hour) by 31.1%
Horton et al. (80)	Randomized, double-blind, placebo-controlled cross over	24	Thalidomide 50–100 mg daily for 12 weeks	Improvement in cough-specific quality of life (CQLQ) (mean difference v. placebo, −11.4 [95% CI, −15.7 to −7.0]; p < 0.001)
Lutherer et al. (96)	Proof of concept, uncontrolled single-arm study	12	IFN-alpha lozenges 150 IU tds for 12 months	Improvement in cough-specific quality of life (LCQ) in 5 of 6 participants*
van Manen et al. (26)	Multi-center prospective observational study	43	Pirfenidone dosed according to clinical practice for 12 weeks	Objective 24-h total cough count decreased by 34% [95% CI, −48 to −15] at 12 weeks
Guler et al. (97)	Randomized, double-blind, placebo-controlled cross over	20	Azithromycin 500 mg three times per week for 12 weeks	No significant change in cough-specific quality of life (LCQ)

CI, confidence interval; CQLQ, Cough Quality of Life Questionnaire; IFN, interferon; IU, international units; LCQ, Leicester Cough Questionnaire; tds, three times per day; VAS, Visual Analog Scale.

^*Secondary endpoint: improvement in cough-specific quality of life measured in a subgroup of participants with chronic cough at 2–3 weeks.