Productive cough, a forgotten phenotype of refractory chronic cough

Refractory chronic cough (RCC) patients typically complain of a dry cough. Sputum production in these patients has rarely been described in the literature. However, sputum production in RCC may be common, troublesome and particularly challenging to manage.

We aimed to characterise patients referred to our regional specialist cough clinic who have significant sputum production (≥1 teaspoon of sputum daily) and compare their demographics, symptomatology and investigation results to those presenting with a dry RCC.

A retrospective case note analysis of all consecutive referrals to a tertiary cough clinic identified as having a productive cough (≥1 teaspoon of sputum daily) was performed over a 12-month period. They were compared to a paired number of patients with dry RCC.

Patients with productive cough represented nearly a quarter (98/398, 24.6 %) of new patient referrals to the clinic. Demographic information, symptomatology and investigation results were comparable to those with a dry RCC. Over a third, 35.8 % of patients with a productive cough reported expectorating an egg-cupful of sputum or more a day. Nearly half, 40% of those with high volume sputum production (≥egg-cupful daily) had both a normal CT thorax and normal spirometry.

Patients with RCC can expectorate significant volumes of sputum in the absence of underlying lung disease. This group have similar demographics to those with dry RCC. This is the first piece of work to our knowledge to describe this cohort. Future work needs to acknowledge this forgotten phenotype to ensure that they receive comprehensive evaluation and evidenced based treatment.