Restricted spirometry and cardiometabolic comorbidities: results from the international population based BOLD study

Abstract

Background: Whether restricted spirometry, i.e. low Forced Vital Capacity (FVC), predicts chronic cardiometabolic disease is not definitely known. In this international population-based study, we assessed the relationship between restricted spirometry and cardiometabolic comorbidities.

Methods: A total of 23,623 subjects (47.5% males, 19.0% current smokers, age: 55.1 ± 10.8 years) from five continents (33 sites in 29 countries) participating in the Burden of Obstructive Lung Disease (BOLD) study were included. Restricted spirometry was defined as post-bronchodilator FVC < 5th percentile of reference values. Self-reports of physician-diagnosed cardiovascular disease (CVD; heart disease or stroke), hypertension, and diabetes were obtained through questionnaires.

Results: Overall 31.7% of participants had restricted spirometry. However, prevalence of restricted spirometry varied approximately ten-fold, and was lowest (8.5%) in Vancouver (Canada) and highest in Sri Lanka (81.3%). Crude odds ratios for the association with restricted spirometry were 1.60 (95% CI 1.37-1.86) for CVD, 1.53 (95% CI 1.40-1.66) for hypertension, and 1.98 (95% CI 1.71-2.29) for diabetes. After adjustment for age, sex, education, Body Mass Index (BMI) and smoking, the odds ratios were 1.54 (95% CI 1.33-1.79) for CVD, 1.50 (95% CI 1.39-1.63) for hypertension, and 1.86 (95% CI 1.59-2.17) for diabetes.

Conclusion: In this population-based, international, multi-site study, restricted spirometry associates with cardiometabolic diseases. The magnitude of these associations appears unattenuated when cardiometabolic risk factors are taken into account.

Keywords: Cardiovascular disease; Comorbidity; Diabetes; Hypertension; Lung function impairment; Restricted spirometry.

Fig. 1

Flow chart of data extraction

Fig. 2

Restricted spirometry prevalence among the different sites. Prevalence of restrictive lung function for each site. Red bar gives the overall mean prevalence. Green bars indicate high-income countries, blue low-income countries

Fig. 3

Forest plot showing the meta-analysis of odds ratios for CVD in participants with restricted spirometry compared with those without it adjusted for sex, age, BMI, smoking (pack-years and current status) and education. Heterogeneity chi-squared = 40.13, d.f. = 26 (p = 0.038). I-squared (variation in ES attributable to heterogeneity) = 35.2%. Estimate of between-study variance Tau-squared = 0.0523. Test for overall effect: Z = 5.66 (p < 0.001). The following sites could not be included in the analysis due to a low number of subjects reporting CVD or singularity in the data: Blantyre (Malawi), Ife (Nigeria), Mumbai (India), Penang (Malaysia), Pune (India), Srinagar (India)

Fig. 4

Forest plot showing the meta-analysis of the adjusted odd ratios for hypertension in participants with restricted spirometry compared to those without it adjusted for sex, age, BMI, smoking (pack-years and current status) and education. Heterogeneity chi-squared = 28.29, d.f. = 31 (p = 0.606). I-squared (variation in ES attributable to heterogeneity) = 0.0%. Estimate of between-study variance Tau-squared = 0.0000. Test for overall effect: Z = 9.94 (p < 0.001). The following sites could not be included in the analysis due to a low number of subjects reporting hypertension: Ife (Nigeria)

Fig. 5

Forest plot showing the meta-analysis of the adjusted odds ratios for diabetes in participants with restricted spirometry compared to those without it adjusted for sex, age, BMI, smoking (pack-years and current status) and education. Heterogeneity chi-squared = 45.34, d.f. = 25 (p = 0.008). I-squared (variation in ES attributable to heterogeneity) = 44.9%. Estimate of between study variance Tau-squared = 0.622. Test for overall effect: Z = 7.77 (p < 0.001). The following sites could not be included in the analysis due to a low number of subjects reporting diabetes or singularity in the data: Cotonou (Benin), Guangzhou (China), Ife (Nigeria), Nampicuan Talugtug (Philippines), Naryn (Kyrgyztan), Pune (India), Srinagar (India)