| Cough post infection was considered as an important cause in subacute cough lasting from 3 to 8 weeks, however, there is few data about cause of subacute cough, only one research report was published in 2006. Neither the incidence nor the pathogenesis of cough post infection is known, it has been thought there was infection of atypical organism in some patients with persistent cough. The aim of this study is to investigate the causes of subacute cough in adults, prevalance of protracted cough post viral infection and the potential infection of atypical organism in cough post infection.Part I The Spectrum of Subacute Cough in Adults and the Investigation of the Clinical Characteristics of DiseasesObjectiveTo investigate the causes and clinical characteristics of subacute cough.MethodsNonsmoking patients with subacute cough and normal chest X ray were enrolled. The diagnostic protocol included history, physical examination, pulmonary function and bronchial hyperresponsiveness tests, cell differentials in induced-sputum, 24 h esophageal pH monitoring, the paranasal sinuses or chest CT, fiberoptic rhinoscopy or bronchoscopy were selected according to patient's situation. The final diagnosis was established by positive response to treatment. The characteristics of the timing, character, onset, and associated symptoms of cough in different causes were compared. Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) for Windows (version 16.0) and quantitative variables were expressed as mean±standard deviation, The incidence of clinical characters of cough and accompanying symptoms, specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) for clinical characters in predicting its cause were calculated. Analysis of variance (ANOVA) or Kruskal-Wallis test was used for comparison of homogeneity and heterogeneity. Non-normal distribution variables were analyzed by Mann-Whitney U test. Aχ2 test was used for statistics of measurement datum.Results1. A total of 116 patients (45 men and 71 women) were recruited and followed up, the mean age was 40.8±13.2 years old, the duration of cough was5.2±1.7 weeks. Definite diagnosis was made in 107 cases (92.2%), with a single cause in 104 cases (97.2%), and multiple causes in 3 patients (2.8%). Cough post infectious was identified in 45 patients (38.1%), 22 with eosinophilic bronchitis (18.6%), 17 with cough variant asthma (14.4%), 12 with upper airway cough syndrome (10.1%), 6 with atopic cough (5.1%), 4 with gastroesophageal reflux (3.4%).2. The incidence of nocturnal cough in cough variant asthma was 29.4% (5/17), higher than in cough post infection (2.2%,χ2 =7.363,P<0.01). The total incidence of nocturnal cough (the part including cough mainly at night and that at day similar to at night) were 82.3%, which were also higher than cough post infection (33.3%,χ2 =11.909,P<0.01). The specificity of nocturnal cough for cough variant asthma was 98.9%.ConclusionsCough post infectious, eosinophilic bronchitis, cough variant asthma and upper airway cough syndrome were common causes of subacute cough. The nocturnal cough is useful in predicting cough variant asthma.PartⅡChanges of Cough After Treatment in Cough Post ObjectiveTo observe the changes of cough after treatment in cough post infection.MethodsThe patients with cough post infection were prescribed an antihistamine-decongestant for 1~2 weeks. Three visits were performed on day 3 and day 7, as well as 8th week of clinical course of cough post infection. Cough symptom score includes cough diary score, cough nighttime score (scale 0-5) and Visual Analogue Scale (VAS) were used as a subjective evaluation to measure the frequency and the severity. Statistical analysis was performed using the SPSS 16.0 and quantitative variables were expressed as mean±standard deviation.Results1 The average of cough diary score was 3 (3 to 4) before treatment, while scores were 3 (0 to 4), 2 (0 to 4) in 3d and 7d, respectively. 71.1% of patients were alleviated in the second following-up.2 The average of cough diary score and nighttime score were 3 (3 to 4), 0 (0 to 2) on the 8th weeks of clinical course, respectively. Cough disappeared or alleviated significantly in 93.4% (42/45) of patients.ConclusionsCough disappeared or alleviated in most patients with cough post infection after treatment with antihistamine-decongestant, and lasting more than 8 weeks in a few patients.PartⅢInvestigation on the Frequency of Cough Post Virus InfectionObjectiveTo investigate the prevalence of the protracted cough post virus infection.Methods Patients with a history of laboratory-confirmed influenza A virus infection were followed up with a telephone questionnaire over 4~16weeks, and the duration of cough had been observed. Statistical analysis was performed using the SPSS 16.0 and quantitative variables were expressed as mean±standard deviation.ResultsA total of 141 patients were followed up, 137 cases suffered cough during the course, while 73.0% of patients were cured in one week, only 8.5% of patients have persistent cough for more than 3 weeks, among which 4 cases over 8 weeks.ConclusionsCough is a common symptom after influenza A virus infection, and lasts less than 3 weeks in most patients, A small proportion of patients presents as protracted cough.PartⅣExamination of Atypical Organism Infection in Patients with Subacute CoughObjectiveTo explore whether there was potential infection of atypical organism in cough post infection.MethodsOne sputum specimen and double nasopharyngeal swab specimens were provided by those subjects. One of the nasopharyngeal swab specimens was used for Bordetella pertussis culture, while the other nasopharyngeal swab specimen and sputum specimen for nucleic acid amplification to detect Bordetella pertussis, Mycoplasma pneumoniae, and Chlamydia pneumoniae.Results1. A total of 57 patients were included in the analysis. The specimens of nasopharyngeal swab and sputum were collected in 45 participants. Chlamydia pneumoniae was detected by PCR in 13 patients. Neither Bordetella pertussis nor Mycoplasma pneumoniae was positive.2. Among the 29 patients of cough post infection, Chlamydia pneumoniae was detected by PCR in 3 patients (10.3%), Both Bordetella pertussis and Mycoplasma pneumoniae were negative.3. Cough disappeared or alleviated after treatment with antihistamine-decongestant but without macrolide antibiotics in patients with cough post infection.ConclusionsAtypical organism infection may not exist in adult patients with cough post infection.Summary1. Cough post infection, eosinophilic bronchitis, cough variant asthma and upper airway cough syndrome were common causes of subacute cough, the nocturnal cough is useful in predicting cough variant asthma.2. Cough disappeared or alleviated in most patients with cough post infection after treatment with antihistamine-decongestant, and lasting more than 8 weeks in a few patients.3. Cough is a common symptom after influenza A virus infection, and lasts less than 3 weeks in most patients, A small proportion of patients presents as protracted cough.4. Atypical organism infection may not exist in adult patients with cough post infection. |
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