[Four-year real-world outcomes and prognostic factors in patients with chronic cough: a prospective observational...

Objective: To determine the 4-year clinical outcomes and systematically analyze key prognostic factors in these patients. Methods: From January 2018 to March 2019, this single-center, prospective observational study enrolled 202 consecutive patients with chronic cough, who underwent baseline assessments followed by 1-year and 4-year follow-up. The primary outcome was cough symptom resolution, categorized as significant improvement or no improvement. Univariate and multivariate analyses were performed to evaluate the impact of demographic factors(age, sex), clinical features (cough duration, smoking history, allergy history), etiological subtypes, Arnold's nerve reflex (ANR), and fractional exhaled nitric oxide (FeNO) on 4-year outcomes. Statistical analyses were performed using SPSS 19.0 software, and receiver operating characteristic curves were employed to assess the sensitivity and specificity of the data. Results: A total of 98 patients (48.5%) completed both 1-year and 4-year follow-up [47 males and 51 females, (35.1±10.3) years]. At 4-year, the rate of significant improvement was significantly higher than at 1 year [82.7% (81/98) vs. 72.5% (71/98), χ²=49.78, P<0.001]. Prognostic analysis showed that the baseline cough duration in the improved group was significantly shorter than that in the non-improved group [0.58 (0.33, 2.00) years vs. 3 (1.84, 7.50) years, Z=-3.42, P=0.001]. Patients with allergy history had lower improvement rates compared with those without allergy [5/13 vs. 85% (76/85), χ²=17.02, P<0.001].The cough variant asthma (CVA) and eosinophilic bronchitis (EB) subgroups had significantly lower improvement rates than the upper airway cough syndrome, gastroesophageal reflux cough, and allergic cough subgroups [73.8% (45/61) vs. 97.3% (36/37), χ²=8.89, P=0.003]. Sex, age, smoking history, ANR, and FeNO showed no significant prognostic value. Multivariate analysis confirmed cough duration (P=0.014), allergy history (P=0.001), and etiological subtype (P=0.022) were independent predictors of 4-year outcomes, while demographic characteristics, smoking history, ANR, and FeNO were not significant. Conclusions: This study demonstrates that over 80% of chronic cough patients achieve significant improvement within 4 years of clinical management. Cough duration, allergy history, and etiological subtype are key determinants of long-term outcomes, highlighting the need for individualized long-term management strategies, particularly for patients with prolonged cough duration and concomitant allergy history in the CVA/EB subgroups.