TABLE 2

Characteristics of patients in included studies

First author [ref.]Total sample sizeSample size of patients with chronic coughType of care/sample typeAge (years)Female (%)Never smoker (%)Current smoker (%)Former smoker (%)Smoking pack history (pack-years)Causes of chronic cough (%)Duration of chronic cough
Adams [24]3960812Other; general populationNRNRNRNRNRNR13.5 (asthma), 7.3 (CB),1.3 (emphysema)NR
Baiardini [8]#166166Secondary/tertiary53.956.034.339.825.9NRNR25 months (sd: 9 months)
Birring [7]104104Secondary/tertiary57.062.5NRNRNRNR100 (UCC)65 months (range: 2.6–650 months)
Campi [25]12041204Secondary/tertiary61.070.461.18.629.0NR1.74 (COPD)39 months
Chamberlain [26]11201120Other; general population51.067.0NR16.5NRNR11.88 (asthma), 7.14 (GORD), 3.57 (PND), 8.75 (bronchitis), 4.38 (COPD), 3.84 (viral infection), 2.41 (cough hypersensitivity syndrome), 0.89 (laryngitis), 1.96 (allergy), other26–65 months (range: 2 months to 10+ years)
Chan [27]5518NR53.032.7100.00.00.0NR100 (sleep disordered breathing, no known respiratory cause of cough)67% (≤8 weeks), 33% (>8 weeks)
Cheng [28]176NRSecondary/tertiary64.356.8NR2.859.78.1715.91 (ACEi), 76.70 (GORD), 11.93 (chronic sinus disease), 28.98 (chronic heart disease), 19.32 (non-ILD chronic lung disease)36.5 months
Çolak [29]14 740554Other; general population58.254.545.610.443.114.8712.64 (asthma), 87.36 (other)NR
Çolak [30]14 669554Other; general population58.255.146.010.543.5NR2.53 (asthma), 0.18 (bronchiectasis), 2.89 (GORD), 1.26 (UACS)NR
Cornford [31]3030Primary48.0NRNRNRNRNRNRNR
Crawford [32]+41NRNRNRNRNRNRNRNR100 (CB)NR
Decalmer [33]6262Secondary/tertiary54.962.9NR0.037.1NR53.23 (GORD), 12.9 (PND), 9.68 (asthma), 3.23 (EB), 3.23 (bronchiectasis), 3.23 (tracheopathia osteochondroplastica)71.5 months (range: 13–390 months)
Everett [34]373373Primary/secondary/tertiary65.373.0NR2.140.8824 (asthma), 66 (no respiratory diagnosis other than cough)84.5 months (range: 0.63–949 months)
Everett [35]4747Secondary/tertiary54.355.3NRNRNRNR100 (GORD)NR
Faruqi [36]86NANANANANANANANANANA
Faruqi [37]2525Secondary/tertiary54.060.00.0NRNRNRNR130 months
Ford [38]3883481Primary40–4956.1NR21.7NRNRNRNR
French [39]8080Secondary/tertiary58.568.897.5NRNRNR86.3 (GORD), 72.5 (UACS), 27.5 (asthma), 5.0 (drug induced), 3.8 (bronchiectasis), 3.8 (postinfectious), 2.5 (NAEB), 2.5 (COPD), 2.5 (laryngeal sensory neuropathy), 1.3 (CHF), 1.3 (bronchiolitis), 1.3 (infiltrate), 1.3 (suppurative airway infection), 1.3 (vocal cord dysfunction), 1.3 (ILD)86 months (sd: 123.7 months)
French [40]3939Secondary/tertiary54.082.1NRNRNRNR40 (PND), 36 (GORD) 15 (asthma), 3 (bronchiectasis), 3 (pertussis), 3 (other)56 months (sd: 63 months)
Fujimura [41]1000232Other; general population55.338.241.622.236.156610.1 (cold), 18.5 (asthma), 7.6 (CB), 6.7 (CVA), 5.9 (GORD), sinusitis, 6.7 (pulmonary emphysema), pneumonia, atopic cough, lung cancer, COPD, 17.6 (CB), 15.1 (unknown)3.8 weeks
Hilton [42]100100Secondary/tertiary60.071.0NR0.0NRNRNR91 (IQR: 52–195 months)
Hsu [14]4714Secondary/tertiary49.157.1NRNRNRNR14.29 (GORD), 21.43 (PND due to paranasal sinusitis or rhinosinusitis), 4 (responsive to inhaled steroid therapy, no wheeze or shortness of breath), 5 (UCC)81.65 months (sd: 79.3 months)
Hulme [43]1414Secondary/tertiary58.985.7NRNRNRNR100 (CRC)82.94 months (sd: 61.49 months)
Kang [44]447447Secondary/tertiary55.167.173.68.318.1NR8.72 (UCC)46% (2–6 months), 14.09% (6–12 months), 21.72% (1–5 years), 18.19% (>5 years)
Kelsall [45]6262Secondary/tertiary56.869.4NR0.0NRNR32.26 (GORD), 37.10 (rhinosinusitis), 6.45 (asthma), 8.06 (EB), 6.45 (bronchiectasis), 29.03 (UCC)42.9 months (IQR: 6–130 months)
Kelsall [46]7070Secondary/tertiary55.072.9100.00.00 (stopped <6 months)NR100 (UCC)62.4 months (IQR: 32.5–131.3 months)
Koo [10]§401401Secondary/tertiary48.461.1NRNRNRNR0 (ILD), 0 (COPD), 0 (asthma), 0 (severe bronchiectasis), 0 (lung cancer)NR
Koskela [47]3697976Other; general population47.882.6NR6.931.46.38NR57% (>13 months), 26% (>65 months)
Koskela [48]3695975Other; general population47.882.6NR31.4NRNR10.25 (asthma), 15.66 (chronic rhinosinusitis), 12.59 (GORD)13.85% (2–12 months), 86.15% (3–8 weeks)
Kuznair [49]136136Secondary/tertiary63.065.463.23.733.1NR64.71 (rhinitis or sinusitis), 36.03 (GORD), 16.18 (asthma), 6.62 (bronchitis), 6.62 (ILD), 5.88 (postinfectious), 4.41 (bronchiectasis), 1.47 (ACEi), 6.62 (others)18 months (IQR: 6–48 months)
Lai [50]11621162Secondary/tertiary42.655.4100.00.00.0NR22.29 (EB), 19.10 (CVA), 12.48 (GORD), 7.31 (UACS), 38.81 (other)27.07 months
Lan [51]164118Secondary/tertiary69.047.041.59.249.425.0761.02 (GORD), 16.95 (ACEi), 12.71 (asthma), 12.71 (UACS), 9.32 (infection)89.7 months (sd: 123.5 months)
Landt [52]41 5452381Other; general population59.955.445.811.542.513.5550.22 (COPD), 49.78 (other)NR
Lätti [53]3673957Other; general population47.882.6NR6.931.46.4115.51 (chronic rhinosinusitis), 11.69 (asthma), 12.59 (GORD)5.42% (<3 weeks), 3.43% (3–8 weeks), 7.27% (>8 weeks)
Lee [54]4928Secondary/tertiary54.855.1NR0.0NRNR21 (asthma), 14 (GORD), 7 (postinfectious disease), 4 (rhinitis), 4 (EB), 4 (OSA), 4 (bronchiectasis), 43 (UCC)41.5 months
Lee [55]100100Secondary/tertiary54.057.080.05.015.0NR24 (asthma), 7 (EB), 9 (rhinitis), 3 (GORD), 29 (UCC), 7 (postviral cough), 6 (sarcoidosis), 8 (ILD), 2 (OSA), 2 (bronchiectasis), 1 (CB), 1 (ACEi), 1 (postinfective)40 months
Lee [56]3217Secondary/tertiary51.359.4100.00.00.0NR24 (asthma), 24 (GORD), 6 (EB), 6 (post-infectious), 6 (bronchiectasis), 35 (UCC)34 months (range: 24–85 months)
Ma [57]200110Secondary/tertiary47.062.0100.00.00.0NR9.09 (UACS), 49.09 (CVA), 5.45 (GORD), 9.09 (NAEB), 8.18 (post virus cough), 9.09 (two causes), 10 (other)9 months (range: 2–360 months)
Mello [58]8888Secondary/tertiary53.172.799.4NRNRNR40 (GORD), 38 (PND), 14 (asthma), 4 (bronchiectasis), 4 (other)85.8 months (sd: 127.4 months)
Morice [59]§255185Secondary/tertiary60.863.1NRNRNRNRNRNR
Murry [60]1616NR29–69NRNRNRNRNR100 (GORD, laryngopharyngeal reflux, and concurrent paradoxical vocal fold movement)8.4 months (sd: 5.3 months)
Ojoo [61]112112Secondary/tertiary56.265.253.65.441.1NR29.35 (reflux related cough), 21.74 (asthma), 11.96 (rhinitis), 4.35 (post-infective), 11.96 (multiple causes), 7.61 (UCC), 13.04 (other)39 months (range: 3.25–832 months)
Ozge [62]165NRSecondary/tertiary43.358.241.238.220.6NR25.6 (asthma), 18 (PND), 21 (sinusitis), 35.6 (CB)46.5 months (sd: 9.6 months)
Sato [63]129129Secondary/tertiary68.540.9NR7.8NR23.054.26 (idiopathic interstitial pneumonias), 37.98 (connective tissue disease-associated ILD), 7.75 (chronic hypersensitivity pneumonitis)NR
Shariat [64]360263Secondary/tertiary39.4100.0NRNRNRNRNR260 months of chest symptoms (range: 6.5–793 months)
Shembel [65]365345Secondary/tertiary53.784.7NRNRNRNR100 (UACS)NR
Sinha [66]223NRNRNRNRNRNRNRNRNRNR
Smith [67]2626Secondary/tertiary68.7NRNR0.0NR42.4100 (COPD)117 months (range: 26–936 months)
Song [68]85737Other; general population76.857.062.212.225.5NR16.2 (asthma), 13.5 (allergic rhinitis), 2.8 (GORD)NR
Ternesten-Hasseus [69]12162Secondary/tertiary53.664.561.30.038.7NR100 (UCC)137.8 months (sd: 130 months)
Van de Kerkhove [70]5151Secondary/tertiaryNA80.4NRNRNRNR100 (UCC)48 months (IQR: 2–192 months)
Vazquez [71]1422552NR54.876.6NR61.7NR37.59100 (COPD)28.13% (3 months to 2 years), 10.69% (>2 years)
Vernon [16]2222Secondary/tertiary66.172.7NRNRNRNR31.82 (GORD), 22.73 (asthma), 18.18 (bronchitis), 18.18 (PND), irritant exposure, post-infectious cough, mild COPD100% (>8 weeks), 81.8% (>52 weeks)
Vernon [15]3924Primary44.171.8NR0.0NRNR20.83 (asthma), 20.83 (GORD), 8.33 (irritable larynx), 12.5 (irritant exposure), 25 (PND), 8.33 (other), 50 (unknown)38.46% (3 weeks to 2 months), 17.95% (2–6 months), 10.26% (6–12 months), 30.77% (>1 year)
Vertigan [72]§3811Secondary/tertiary56.177.0NR11.0NRNR49 (reflux), 29 (asthma), 17 (rhinitis)NR
Vertigan [73]171111Secondary/tertiary53.376.6NRNRNRNR50.45 (CRC), 49.55 (CRC/paradoxical vocal fold movement)NR
Vertigan [74]171111Secondary/tertiary56.476.6NR3.5NRNR55 (GORD), 18 (asthma), 49 (PND), 35 (allergies)NR
Vertigan [75]5353Secondary/tertiary60.066.0100.00.00.0NR100 (CRC)59 months
Won [76]478478Secondary/tertiary55.168.474.77.717.7NR12.97 (UCC), 87.03 (chronic cough with unspecified underlying condition)44% (8–24 weeks), 13.8% (24–48 weeks), 21.6% (52–269 weeks), 20.6% (>260 weeks)
Xu [77]8787Secondary/tertiary45.155.2NRNRNRNR100 (GORD)8.28 months (sd: 30.83 months)
Zhan [11]237237Secondary/tertiary40.454.0NRNRNRNRNR43 months (sd: 77.3 months)

NR: not reported; CB: chronic bronchitis; UCC: unexplained chronic cough; GORD: gastro-oesophageal reflux disease; PND: post-nasal drip; ACEi: angiotensin-converting-enzyme inhibitor use; ILD: interstitial lung disease; UACS: upper airway cough syndrome; EB: eosinophilic bronchitis; NA: not applicable; NAEB: non-asthmatic eosinophilic bronchitis; CHF: chronic heart failure; CVA: cough-variant asthma; CRC: chronic refractory cough; OSA: obstructive sleep apnoea. #: item generation and reduction sample; : item reduction and validation sample; +: item generation sample; §: validation sample.