Cough is a common symptom of scleroderma-related interstitial lung disease (SSc-ILD), but its relationship to other characteristics of SSc-ILD, impact on cough-specific QoL and response to therapy for SSc-ILD have not been well studied.
We investigated frequent cough (FC) in SSc-ILD patients (N=142) enrolled in Scleroderma Lung Study II, a randomized controlled trial comparing mycophenolate mofetil (MMF) and oral cyclophosphamide (CYC) as treatments for ILD. We determined the impact of FC on QoL (Leicester Cough Questionnaire [LCQ]), evaluated change in FC in response to treatment for SSc-ILD, and examined the relationship between gastroesophageal reflux disease (GERD) and cough during the trial.
Study participants who reported FC at baseline (61.3%) reported significantly more dyspnea, exhibited more extensive ILD on HRCT, had a lower diffusing capacity for carbon monoxide (DLCO) and reported more GERD symptoms than those without FC. Cough-specific QoL was modestly impaired in patients with FC (total LCQ score 15.4±3.7; normal range 3-21, higher scores indicating worse QoL). The proportion of patients with FC at baseline declined by 44% and 41% over 2 years in the CYC and MMF treatment arms, respectively, and this decline was significantly related to changes in GERD and ILD severity.
Frequent cough occurs commonly in SSc-ILD, correlates with both the presence and severity of GERD and ILD at baseline and declines in parallel with improvements in both ILD and GERD during a 2-year course of therapy. Frequent cough might serve as a useful surrogate marker of treatment response in SSc-ILD trials.