Functional brain imaging in individuals with chronic cough demonstrates reduced activation in cortical regions associated with voluntary cough suppression. Little is known about the ability of patients with chronic cough to suppress cough. This study aimed to compare the ability to voluntarily suppress cough during inhaled capsaicin challenge in participants with chronic refractory cough with that in healthy controls. In addition, this study aimed to assess the repeatability of capsaicin challenge test with voluntary cough suppression.Participants with chronic refractory cough and healthy controls underwent inhaled capsaicin challenge tests while attempting to suppress their cough responses. After 5 days, either a conventional capsaicin challenge test with no cough suppression attempt, or a repeat test with an attempt at cough suppression was performed. Threshold capsaicin concentrations required to elicit one, two and five coughs were calculated by interpolation. Objective 24-h cough frequency was measured in individuals with chronic refractory cough.Healthy controls were able to suppress capsaicin-evoked cough while participants with chronic refractory cough were not. Geometric mean±sd capsaicin dose thresholds for five coughs with (CS5) and without (C5) suppression attempts were 254.40±3.78 versus 45.89±3.95 µmol·L−1, respectively, in healthy controls (p=0.033) and 3.34±5.04 versus 3.86±5.13 µmol·L−1, respectively, in participants with chronic refractory cough (p=0.922). Capsaicin dose thresholds for triggering five coughs with self-attempted cough suppression were significantly lower in participants with chronic refractory cough than in healthy controls; geometric mean±sd 4.94±4.43 versus 261.10±4.34 µmol·L−1, respectively; mean difference (95% CI) 5.72 (4.54–6.91) doubling doses (p<0.001). Repeatability of cough suppression test in both patients and healthy controls was high; intraclass correlation coefficients of log(CS5) values 0.81 and 0.87, respectively. CS5 was associated with objective cough frequency (ρ=−0.514, p=0.029).Participants with chronic refractory cough were less able to voluntarily suppress capsaicin-evoked cough compared to healthy controls. This may have important implications for the pathophysiology and treatment of chronic cough.

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Cough reflex hypersensitivity (CRH) and impaired cough suppression are features of chronic refractory cough (CRC). Little is known about cough suppression and CRH in cough associated with chronic obstructive pulmonary disease (COPD). This study investigated the ability of participants with COPD to suppress cough during a cough challenge test in comparison to participants with CRC and healthy subjects. This study also investigated whether CRH is associated with chronic cough in COPD.Participants with COPD (n=27), CRC (n=11), and healthy subjects (n=13) underwent capsaicin challenge test with and without attempts to self-suppress cough in a randomised order over 2 visits, 5 days apart. For participants with COPD, the presence of self-reported chronic cough was documented, and objective 24-h cough frequency was measured.Amongst participants with COPD, those with chronic cough (n=16) demonstrated heightened cough reflex sensitivity (CRS) compared to those without chronic cough (n=11); geometric mean (sd) capsaicin dose thresholds for 5 coughs (C5) 3.36 (6.88) versus 44.50 (5.90) µmol·L−1 respectively (p=0.003). Participants with CRC also had heightened CRS compared to healthy participants; geometric mean (sd) C5 3.86 (5.13) versus 45.89 (3.95) µmol·L−1 respectively (p<0.001). Participants with COPD were able to suppress capsaicin-evoked cough, regardless of the presence or absence of chronic cough; geometric mean (sd) capsaicin dose thresholds for 5 coughs without self-suppression attempts (C5) and with (CS5) were 3.36 (6.88) versus 12.80 (8.33) µmol·L−1 (p<0.001) and 44.50 (5.90) versus 183.2 (6.37) µmol·L−1 (p=0.006) respectively. This was also the case for healthy participants (C5 versus CS5: 45.89 (3.95) versus 254.40 (3.78) µmol·L−1, p=0.033), but not those with CRC, who were unable to suppress capsaicin-evoked cough (C5 versus CS5: 3.86 (5.13) versus 3.34 (5.04) µmol·L−1, p=0.922). C5 and CS5 were associated with objective 24-h cough frequency in participants with COPD; ρ=−0.430, p=0.036 and ρ=−0.420, p=0.041 respectively.Participants with COPD-chronic cough and CRC both have heightened cough reflex sensitivity but in contrast, only participants with CRC were unable to suppress capsaicin evoked cough. This suggests differing mechanisms of cough between participants with COPD and CRC, and the need for disease specific approaches to its management.

Purpose Reduced physical activity in many chronic diseases is consistently associated with increased morbidity. Little is known about physical activity in sarcoidosis. The aim of this study was to objectively assess physical activity in patients with pulmonary sarcoidosis and investigate its relationship with lung function, exercise capacity, symptom burden, and health status. Methods Physical activity was assessed over one week in 15 patients with pulmonary sarcoidosis and 14 age-matched healthy controls with a tri-axial accelerometer (ActivPal™) and the International Physical Activity Questionnaire (IPAQ). All participants underwent pulmonary function tests, 6-min walk test (6MWT) and completed the Fatigue Assessment Scale (FAS), Medical Research Council (MRC) Dyspnoea Scale and the King’s Sarcoidosis Questionnaire (KSQ). Results Patients with sarcoidosis had significantly lower daily step counts than healthy controls; mean (SD) 5624 (1875) versus 10,429 (2942) steps ( p < 0.01) and a trend towards fewer sit-to-stand transitions each day ( p = 0.095). Only two patients (13%) self-reported undertaking vigorous physical activity (IPAQ) compared to half of healthy individuals ( p < 0.01). Daily step count was significantly associated with 6MWT distance in sarcoidosis ( r = 0.634, p = 0.01), but not with forced vital capacity ( r = 0.290), fatigue ( r = 0.041), dyspnoea ( r = −0.466) or KSQ health status ( r = 0.099–0.484). Time spent upright was associated with fatigue ( r = −0.630, p = 0.012) and health status (KSQ Lung scores r = 0.524, p = 0.045), and there was a significant correlation between the number of sit-to-stand transitions and MRC dyspnoea score ( r = −0.527, p = 0.044). Conclusion Physical activity is significantly reduced in sarcoidosis and is associated with reduced functional exercise capacity (6MWD). Fatigue, exertional symptoms and health status were more closely associated with time spent upright and the number of bouts of physical activity, as compared to step counts. Further studies are warranted to identify the factors that determine different physical activity profiles in sarcoidosis. Electronic supplementary material The online version of this article (10.1007/s00408-019-00215-6) contains supplementary material, which is available to authorized users.