Defining Chronic Cough: A Systematic Review of the Epidemiological Literature

PURPOSE: Recent evidence suggests a global burden of chronic cough in general populations. However, the definitions vary greatly among epidemiological studies, and none have been validated for clinical relevance. We aimed to examine previous epidemiological definitions in detail and explore the operational characteristics. METHODS: A systematic review was conducted for epidemiological surveys that reported the prevalence of chronic cough in general adult populations during the years 1980 to 2013. A literature search was performed on Pubmed and Embase without language restriction. Epidemiological definitions for chronic cough were classified according to their components, such as cutoff duration. Meta-analyses were performed for the male-to-female ratio of chronic cough prevalence to explore operational characteristics of epidemiological definitions. RESULTS: A total of 70 studies were included in the systematic review. The most common epidemiological definition was identified as 'cough > or =3 months' duration without specification of phlegm (n=50); however, it conflicted with the cutoff duration in current clinical guidelines (cough > or =8 weeks). Meta-analyses were performed for the male-to-female ratio of chronic cough among 28 studies that reported sex-specific prevalence using the most common definition. The pooled male-to-female odds ratio was 1.26 (95% confidence interval 0.92-1.73) with significant heterogeneity (I2=96%, P<0.001), which was in contrast to clinical observations of female predominance from specialist clinics. Subgroup analyses did not reverse the ratio or reduce the heterogeneity. CONCLUSIONS: This study identified major issues in defining chronic cough in future epidemiological studies. The conflict between epidemiological and clinical diagnostic criteria needs to be resolved. The unexpected difference in the gender predominance between the community and clinics warrants further studies. Clinical validation of the existing definition is required.

Chronic cough: an Asian perspective. Part 1: Epidemiology

Asia is one of the most diverse and dynamic continents. Due to recent rapid industrialisation and urbanisation, morbidity patterns are likely to be diverse in Asian populations. Chronic cough is a disease condition resulting from host-environmental interactions, and is associated with a high global epidemiological burden. However, the underlying epidemiology remains unclear, particularly in Asia. We performed a literature search to identify peer-reviewed articles on chronic cough in community-based adult Asian populations that have been published between January 2000 and June 2015. In this review, we aim to examine the epidemiological characteristics and determinants of chronic cough in several geographical areas of Asia.

Comparison of the effect of high-dose inhaled budesonide and fluticasone on adrenal function in patients with severe chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease [COPD] is a leading cause of respiratory-related morbidity and mortality. Inhaled steroids are frequently used in patients with moderate to severe disease and may lead to adrenal suppression. The aim of this study was to compare the effect of inhaled budesonide/formoterol with inhaled fluticasone/salmeterol in severe COPD. It was a prospective open-label crossover study of 22 patients. Adrenal suppression was measured by overnight urinary cortisol/creatinine ratio. The measurements were taken while patients were on either combination for at least 4 weeks. A total of 12 patients completed the study. The mean age was 64 years [8 males, 4 females]. The mean FEV1 was 1 L [range, 0.5-1.8]. There was no significant difference in adrenal suppression measured by overnight urinary cortisol/creatinine ratio [budesonide 5.2 +/- 4.3, fluticasone 4.7 +/- 3.1; 95% CI -2.2 to 1.2; P = 0.52] and urinary cortisol concentration [budesonide 51 +/- 53, fluticasone 43 +/- 31 [nmol/l]; 95% CI -35 to 20; P = 0.56]. Inhaled budesonide and fluticasone have no significantly different effect on adrenal function in moderate to severe COPD. The adverse event profile of high-dose inhaled steroids should not influence the choice of medication