2018 Section 6 - Laryngology, Voice Disorders, and Bronchoesophalogy

TABLE 2 ] Ranking of Risk Factors for Chronic Cough in the General Population Ranking by OR

Ranking by PAR

P Value a

PAR b , %

Prevalence, %

Risk Factor

Risk Factor

OR (95% CI)

Bronchiectasis

5.4 (2.5-12)

< .001 < .001 < .001 < .001 < .001

< 1

Smoking

20

Asthma

2.5 (1.9-3.2)

7

Low income

19

Abdominal obesity c Air fl ow limitation d

Occupational exposure to dust/fumes 2.0 (1.6-2.6)

7

18

Air fl ow limitation d

1.8 (1.5-2.2)

21

14

Gastroesophageal re fl ux disease

1.8 (1.4-2.3)

9

Low vegetable intake

10

Upper airway cough syndrome

1.8 (1.3-2.5)

.001

4

Asthma

9

Low income

1.5 (1.2-1.8)

< .001

47

Occupational exposure to dust/fumes Gastroesophageal re fl ux disease Upper airway cough syndrome

7

Smoking

1.5 (1.2-1.8)

< .001

54

7

Low vegetable intake

1.5 (1.2-1.7)

< .001

26

3

Abdominal obesity c

1.4 (1.2-1.7)

< .001

53

Bronchiectasis

1

Female sex

1.2 (0.97-1.4)

.10

55

Female sex

(8)

All risk factors were dichotomized and ranked according to signi fi cance level in a stepwise logistic regression model including sex, smoking, asthma, allergy, air fl ow limitation, gastroesophageal re fl ux disease, upper airway cough syndrome, bronchiectasis, pulmonary fi brosis, occupational exposure to dust/fumes, daily exposure to passive smoking, use of medication for hypertension, being overweight, abdominal obesity (de fi ned with waist-hip ratio), low education, low income, and high and low intake of various types of food (red meat, white meat, fast-food, fruits, and vegetables) and beverages (tea, coffee, milk, soda, and alcohol). Age was automatically included and was not subjected to the stepwise estimation process. The PAR value for female sex is in parenthesis, because this risk factor was not signi fi cantly associated with chronic cough after adjusting for age, but was forced into the model. PAR ¼ population attributable risk. a ORs and P values were by Wald test from logistic regression adjusted for age. b PAR was calculated as ( f [OR ‒ 1]) / (1 þ f [OR ‒ 1]), where f is the frequency of the risk factor in the population and OR is the OR for chronic cough in the population. c Abdominal obesity was waist-hip ratio $ 0.85 for women and $ 0.90 for men. 20 d Air fl ow limitation was FEV 1 /FVC < 70%. 12

social domain. To our knowledge, this is the fi rst study to determine the prevalence and impact of chronic cough in the general population. Our estimate of the prevalence of chronic cough in the general population represents the best estimate available, and although it is somewhat lower than has been reported in more limited studies, 2 it is very similar to the reported prevalence of chronic cough in patients randomized to placebo in large trials of angiotensin-converting enzyme inhibitor therapy. 21-24 Potential mechanisms and explanations for many of the identi fi ed risk factors associated with chronic cough in this study have been described previously. 8-10 Bronchiectasis arises from changes in the architecture of the airways that can be acquired (eg, pneumonias) or be congenital (eg, cystic fi brosis, primary ciliary dyskinesia), and the main clinical features of the disease include increased sputum production and chronic cough. 25 Because the treatment of bronchiectasis may be dif fi cult, interdisciplinary specialized initiatives are necessary. 26 Asthma is associated with chronic airway in fl ammation with accompanying respiratory symptoms, including cough. 27 Chronic cough in individuals with asthma may

be representative of the eosinophilic phenotype that is often associated with cough-variant asthma or eosinophilic bronchitis. 1 In some cases, chronic cough in individuals with asthma may be a sign of undertreatment, and these individuals will likely bene fi t from treatment with inhaled corticosteroids, in particular in the eosinophilic endotype, including cough-variant asthma and eosinophilic bronchitis. 11,27,28 Occupational exposure to noxious gasses or particles may induce airway in fl ammation and is often associated with different respiratory symptoms, including sputum production and coughing, that may be a sort of autonomous defense mechanism to repel the inappropriate stimulus. Therefore, a thorough occupational anamnesis should be taken. Individuals suffering from chronic cough caused by occupational exposure need to use protection or switch working environment, or as a last resort change occupation. Intriguing, occupational exposure was only a risk factor in former smokers, which may be related to the fact that smoking is most prevalent in blue collar workers and warrants further investigation.

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