Table 2. Diseases excluded, follow-up, and cough duration of included studies.
| Study | Inclusion/exclusion criteria | Follow-up | Duration of cough |
|---|---|---|---|
| Van de Kerkhove et al.23 | All patients failed empirical treatment trials with proton pump inhibitors (≥6 wk of omeprazole 40 mg twice daily), nasal decongestants, (≥6-wk fluticasone 100 μg twice daily or equivalent) and inhaled steroids (≥6-wk fluticasone 250 μg twice daily or equivalent) | Mean follow-up, unknown | Median duration 48 mo |
| Ryan et al.6 | Normal spirometry and a negative response to previously trialled proton pump inhibitor, inhaled corticosteroid treatment, oral corticosteroids or nasal steroid treatment. | 1 mo | 30 mo |
| 3 mo | 96 mo | ||
| Bastian and Bastian24 | Gastroesophageal reflux disease, asthma, and allergy with no reduction of cough were included | ≥6 mo | Median 60 mo |
| Ting and Na22 | Normal spirometry and a negative response to previously trialled proton pump inhibitor, corticosteroid treatment, antitussive, SABA | NR | Gabapentin: median 32 mo; range 13–96 mo |
| Structural disease were exclued | Placebo: median 39 mo; range 11–90 mo | ||
| Lee and Woo14 | Prior workup included (not systematic or uniform across all patients): | Mean follow-up, unknown | Median 7.5 mo; range 1.5–240 mo |
| Modified barium swallow | |||
| CT | |||
| MRI | |||
| pH testing | |||
| Ryan et al.17 | Smoking | Treatment visits after 4 wk and 8 wk of treatment; additional assessment 4 wk after drug cessation | Gabapentin: median 36 mo; range 18–150 mo |
| Pulmonary disease or infection (including asthma, productive cough) | Placebo: median 48 mo; range 18–156 mo | ||
| Reflux | |||
| Postnasal drip | |||
| ACEI | |||
| Pregnant/breastfeeding | |||
| Impaired liver function | |||
| Mintz and Lee15 | Not systematic or uniform across patients: gastroesophageal reflux disease, asthma, postnasal drip exclusion mentioned in the abstract; article mentions privious workup, including bronchoscopy, upper gastrointestinal series, bronchoalveolar lavage, methacholine challenge test, serology (ANA, IgG, pertussis IgA, α-1-antitrypsin, etc.) | 12 mo | Median 7.5 mo; range 1.5–240 mo; mean±SD 31.4±57.4 |
SABA: short-acting β2 agonist; NR: not reported in study; CT: computed tomography; MRI: magnetic resonance imaging; ACEI: angiotensin-converting enzyme inhibitors; ANA: anti-nuclear antibody.