Heredity of chronic bronchitis: a registry-based twin study

Structural airway imaging metrics are differentially associated with persistent chronic bronchitis

BACKGROUND

Chronic bronchitis (CB) is strongly associated with cigarette smoking, but not all smokers develop CB. We aimed to evaluate whether measures of structural airway disease on CT are differentially associated with CB.

METHODS

In smokers between ages 45 and 80 years, and with Global Initiative for Obstructive Lung Disease stages 0-4, CB was defined by the classic definition. Airway disease on CT was quantified by (i) wall area percent (WA%) of segmental airways; (ii) Pi10, the square root of the wall area of a hypothetical airway with 10 mm internal perimeter; (iii) total airway count (TAC) and (iv) airway fractal dimension (AFD), a measure of the complex branching pattern and remodelling of airways. CB was also assessed at the 5-year follow-up visit.

MEASUREMENTS AND MAIN RESULTS

Of 8917 participants, 1734 (19.4%) had CB at baseline. Airway measures were significantly worse in those with CB compared with those without CB: WA% 54.5 (8.8) versus 49.8 (8.3); Pi10 2.58 (0.67) versus 2.28 (0.59) mm; TAC 156.7 (81.6) versus 177.8 (91.1); AFD 1.477 (0.091) versus 1.497 (0.092) (all p<0.001). On follow-up of 5517 participants at 5 years, 399 (7.2%) had persistent CB. With adjustment for between-visits changes in smoking status and lung function, greater WA% and Pi10 were associated with significantly associated with persistent CB, adjusted OR per SD change 1.75, 95% CI 1.56 to 1.97; p<0.001 and 1.66, 95% CI 1.42 to 1.86; p<0.001, respectively. Higher AFD and TAC were associated with significantly lower odds of persistent CB, adjusted OR per SD change 0.76, 95% CI 0.67 to 0.86; p<0.001 and 0.69, 95% CI 0.60 to 0.80; p<0.001, respectively.

CONCLUSIONS

Higher baseline AFD and TAC are associated with a lower risk of persistent CB, irrespective of changes in smoking status, suggesting preserved airway structure can confer a reserve against CB.

Incidence and Longitudinal Changes in Prevalence of Chronic Bronchitis in Farm and Non-Farm Rural Residents of Saskatchewan

OBJECTIVE

To assess the predictors associated with incidence and longitudinal changes in the prevalence of chronic bronchitis (CB) among farm and non-farm residents of rural Saskatchewan, Canada.

METHODS

The Saskatchewan Rural Health Study was a prospective study of the lung health of rural dwellers. We obtained information on 4624 households, 8261 individuals (2797 households, 4867 individuals) at baseline (follow-up).

RESULTS

Incidence of CB was 4.3% over 4 years. The prevalence was 6.4% and 5.3% (baseline) and 12.1% and 9.2% (follow-up) in non-farm and farm residents, respectively. The prevalence of CB was associated with current smokers; father ever had lung trouble; obesity; mother smoked during pregnancy; allergic reaction to cats and to pollen; household income inadequacy and age.

CONCLUSION

Prevalence and incidence of CB in rural people appear to be a complex mix of personal and contextual factors.

Self-reported intake of fruit and vegetables and risk of chronic obstructive pulmonary disease: A nation-wide twin study

BACKGROUND

Although smoking is the major risk factor for chronic obstructive pulmonary disease (COPD) many patients with obstructive lung function suggesting COPD are never-smokers. Therefore, other lifestyle factors have been suggested as risk factors.

AIMS

i) To examine the association between self-reported intake of fruit and vegetables and risk of COPD and ii) to examine whether the association between these traits are due to underlying genetic factors.

METHODS

12,449 twins, aged 40-80, from the Danish Twin Registry were recruited. The participants completed a questionnaire on medical history and lifestyle factors and participated in clinical examination. COPD was defined according to ATS/ERS recommendations. Multivariate logistic regressions were used to estimate the risk of COPD in individuals with a low intake of fruit and vegetables. Co-twin control analyses were performed to examine whether the association between fruit and vegetables and COPD is explained by genetic factors. Self-reported physician-diagnosed asthmatic individuals were excluded.

RESULTS

Of the 11,458 individuals were included in the analyses, 48% of the participants were males. Mean age was 58.9 (years)±SD 9.6, mean BMI (kg/m²)26.6 ± SD 4.4. A multivariate logistic regression, including sex, age and BMI showed that both smoking, no and heavy drinking and physical inactivity were independent predictors of COPD. There was a significant frequency-pendent association between intake of fruit and vegetables and increased risk of COPD. Conditional logistic regression analyses showed that the association might be controlled by genetic factors.

CONCLUSIONS

This study shows that low intake of fruit and vegetables is associated with an increased risk of COPD and the association might be under influence of genetic factors.

Grading Severity of Productive Cough Based on Symptoms and Airflow Obstruction

The binary approach to the diagnosis of Chronic Bronchitis (CB) is a major barrier to the study of the disease. We investigated whether severity of productive cough can be graded using symptoms and presence of fixed airflow obstruction (FAO), and whether the severity correlates with health status, exposures injurious to the lung, biomarkers of inflammation, and measures of airway wall thickening. Findings from a cross-sectional sample of 1,422 participants from the Lovelace Smokers Cohort (LSC) were validated in 4,488 participants from the COPDGene cohort (COPDGene). Health status was based on the St. George's Respiratory Questionnaire, and Medical Outcomes Study 36-Item Short Form Health Survey. Circulating CC16 levels were quantified by ELISA (LSC), and airway wall thickening was measured using computed tomography (COPDGene). FAO was defined as postbronchodilator FEV1/FVC <0.7. The presence and duration of productive cough and presence of FAO or wheeze were graded into Healthy Smokers, Productive Cough (PC), Chronic PC, PC with Signs of Airflow Obstruction, and Chronic PC with Signs of Airflow Obstruction. In both cohorts, higher grade of severity correlated with lower health status, greater frequency of injurious exposures, greater airway wall thickening, and lower circulating CC16 levels. Further, longitudinal follow-up suggested that disease resolution can occur at every grade of severity but is more common in groups of lower severity and least common once airway remodeling develops. Therefore, severity of productive cough can be graded based on symptoms and FAO and early intervention may benefit patients by changing the natural history of disease.

The outcome and the influencing factors of the age of onset in post-mortem of chronic bronchitis patients: a retrospective study

Purpose

Chronic bronchitis is thought to occur in elderly patients, and smoking seems to be an important risk factor. The outcomes related to the age of onset in patients with chronic bronchitis are still unclear.

Patients and methods

A retrospective study was conducted on deceased patients whose diagnosis included bronchitis from 2010 to 2016. Patients were separated into two groups according to the age of onset (Group I, age ≤50 years old; Group II, age >50 years old). Information regarding disease course, smoking history, death age, number of admissions per year, Hugh Jones Index, and self-reported comorbidities of the patients was recorded.

Results

The courses of chronic cough and sputum were 33.38±7.73 years and 14.44±8.60 years in Group I and Group II, respectively (p<0.05). The death ages of Group I and Group II were 77.65±7.87 years and 84.69±6.67 years, respectively (p<0.05). There was a significant negative correlation between the number of hospital admissions per year and the age of onset. The age of onset was negatively associated with daily smoking count (r=−0.210) and total smoking count (r=−0.146). In Group I, there were fewer cases of coronary heart disease (OR =0.41 [0.24–0.71]), neurological diseases (OR =0.48 [0.24–0.97]), and total comorbidities (OR =0.67 [0.54–0.85]) than in Group II.

Conclusion

Patients with early onset chronic bronchitis had a longer history, younger death age, poorer health status, and lower incidence of comorbidities.

The chronic bronchitis phenotype in chronic obstructive pulmonary disease: features and implications

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) is a major public health problem that is projected to rank fifth worldwide in terms of disease burden and third in terms of mortality. Chronic bronchitis is associated with multiple clinical consequences, including hastening lung function decline, increasing risk of exacerbations, reducing health-related quality of life, and possibly raising all-cause mortality. Recent data suggest greater elucidation on the risk factors, radiologic characteristics, and treatment regimens. Our goal was to review the literature on chronic bronchitis that has been published in the past few years.

RECENT FINDINGS

A growing body of literature that more carefully describes environmental risk factors, epidemiology, and genetics associated with chronic bronchitis. In addition, as computed tomography technology continues to improve, the radiologic phenotype associated with chronic bronchitis is better understood.

SUMMARY

With these new data, the clinician can recognize the newly described risk factors and the associated phenotype for chronic bronchitis and entertain new treatment options for this high-risk population.

Vitamin D binding protein gene polymorphisms and chronic obstructive pulmonary disease: a meta-analysis

BACKGROUND

A number of polymorphisms in vitamin D binding protein (VDBP) (GC) gene have been implicated in risk of chronic obstructive pulmonary disease (COPD), but the results were controversial. GC1F, GC1S, and GC2 are three common variants of the VDBP gene [single nucleotide polymorphisms (SNPs): rs7041 and rs4588], which were reported to be associated with COPD. This study aimed to explore the association between VDBP gene polymorphisms and COPD.

METHODS

PubMed, EMBASE, Web of Science (Medline) and Chinese National Knowledge Infrastructure (CNKI) were searched for eligible case-control studies. Study quality was evaluated using the Newcastle-ottawa quality assessment scale (NOS). After the most appreciated genetic model was identified, a meta-analysis was performed to test the association between VDBP gene polymorphism and COPD. The pooled odds ratios (ORs) were performed respectively for the most appreciated genetic model, single allele comparison and homozygous gene model analysis. Summary receiver operating characteristic curve (SROC) analyses were applied to evaluate the diagnostic performance of polymorphism of VDBP to COPD.

RESULTS

Eight studies containing 2,216 participants were included. The analyses of the most appropriate genetic models offered significant results in recessive model of GC1F/1S group (OR =2.18), co-dominant genetic model in GC1F/2 group (1F-1F vs. 2-2: OR =4.87; 1F-2 vs. 2-2: OR =1.73; 1F-1F vs. 1F-2: OR =2.27). In single allele comparison, significant results were obtained in GC1F vs. GC1S and GC1F vs. GC2, with ORs were 1.47 and 1.77, respectively. In homozygous genes comparison, the OR was 2.51 in GC1F homozygote vs. other genotypes. Subgroup analyses offered the same significant results in Asian population, but not in Caucasian population. The SROC analyses showed the less accurate performance of polymorphism of VDBP to COPD.

CONCLUSIONS

There is a close association between COPD and GC gene polymorphisms. The GC1F allele could be a risk factor, the GC1S and GC2 allele may be protective factors in Asian, but not in Caucasians.

Familial transmission of chronic obstructive pulmonary disease in adoptees: a Swedish nationwide family study

OBJECTIVES

Familial clustering of chronic obstructive pulmonary disease (COPD) is well established, but the familial risk of COPD has not been determined among adoptees. The aim was to determine whether the familial transmission of COPD is related to disease in biological and/or adoptive parents.

DESIGN

Historic cohort study.

PARTICIPANTS

80,214 (50% females).

METHODS

The Swedish Multi-Generation Register was used to follow all Swedish-born adoptees born in 1932-2004 (n=80,214) between 1 January 1964 and 31 December 2010 for COPD (n=1978). The risk of COPD was estimated in adoptees with at least one biological parent with COPD but no adoptive parent with COPD (n=162) compared with adoptees without a biological or adoptive parent with COPD. The risk of COPD was also determined in adoptees with at least one adoptive parent but no biological parent with COPD (n=110), and in adoptees with both affected biological and adoptive parents (n=162).

PRIMARY OUTCOME MEASURE

COPD in adoptees.

RESULTS

Adoptees with COPD in at least one biological parent but no adoptive parent were more likely to have COPD than adoptees without a biological or adoptive parent with COPD (standardised incidence ratio, SIR=1.98 (95% CI 1.69 to 2.31)). The familial SIR for adoptees with both a biological parent and an adoptive parent with COPD was 1.68 (95% CI 1.39 to 2.00). Adoptees with at least one adoptive parent with COPD but no biological parent with COPD were not at an increased risk of COPD (SIR=1.12 (95% CI 0.92 to 1.35)).

CONCLUSIONS

The findings of the study show that the familial transmission of COPD is associated with COPD in biological but not adoptive parents, suggesting that genetic or early life factors are important in the familial transmission of COPD.