ATS 2013, PHILADELPHIA ─ People who are consistently exposed to both wood smoke and tobacco smoke are at a greater risk for developing chronic obstructive pulmonary disease (COPD) and for experiencing more frequent and severe symptoms of the disease, as well as more severe airflow obstruction, than those who are exposed to only one type of smoke, according to the results of a new population-based study conducted by researchers in Colombia.
The results of the study will be presented at the ATS 2013 International Conference.
"Although previous studies have shown a definite link between wood smoke exposure and the development of COPD, those studies were case-controls and case series of patients with similar disease or health profiles," said study lead author Carlos Torres-Duque, M.D., director of research at the Fundacion Neumologica Colombiana in Bogota. "This new data derives from a population-based study that looked at wood smoke exposure and the overall prevalence of COPD, as well as the characteristics of the disease and those who suffer from it."
About 40 percent of the world's population uses solid fuels - especially wood - for cooking or heating, he noted.
For this study, Dr. Torres-Duque and his colleagues used data from the PREPOCOL (Prevalencia de la Enfermedad Pulmonar Obstructiva Crónica en Colombia) study which evaluated the prevalence of COPD among the adult residents of five Colombian cities. The study included 5,539 subjects, 8.9 percent of whom were diagnosed with COPD. The study participants were divided into four groups: those who were exposed to wood smoke and who had never smoked tobacco (30.9 percent); those who were exposed to tobacco smoke but had no exposure to wood smoke (18.7 percent); those who had been exposed to both types of smoke (29.8 percent); and those who had exposure to neither type of smoke (20.6 percent).
Patients' lung function was measured using spirometry, a technique used to measure the amount of air a person is able to inhale and exhale, and all patients completed a standardized respiratory questionnaire to identify exposure to smoke.
In their initial review of data, the researchers learned that 53 percent of those diagnosed with COPD had both wood and tobacco smoke exposure; moreover, the prevalence of COPD increased as exposure to wood smoke increased.
After adjusting for specific factors including age, active and passive tobacco smoking, education level, history of TB and altitude, the researchers found that wood smoke exposure of 10 or more years posed a significant risk factor for developing COPD in both men and women and those with both wood and tobacco exposure had poorer lung function scores and more phlegm and coughed more frequently than those who had exposure to only one type of smoke.Among the COPD population, those who were exposed only to wood smoke tended to be women, to have higher BMIs and to be shorter than those exposed to tobacco smoke or to a combination of wood and tobacco smoke.
"In the population we studied, exposure to wood smoke was identified as an independent risk factor for developing COPD, both in women and men," Dr. Torres-Duque said. "In addition, the prevalence of COPD was significantly higher in those who were exposed to both wood and tobacco smoke and those with both exposures had more symptoms and more severe disease than those who were exposed to only one type of smoke."
This result suggests that the combination of wood and tobacco smoke produces an additive effect that causes an increase in COPD prevalence and in the frequency of COPD symptoms, he added.
"It is also possible that the responses of the lungs and airways could vary, based on the pollutants to which they're exposed," Dr. Torres-Duque noted.
Future studies might provide additional data regarding varying responses and help clinicians determine specific treatments based on exposures, he said.
* Please note that numbers in this release may differ slightly from those in the abstract. Many of these investigations are ongoing; the release represents the most up-to-date data available at press time.
Chronic Obstructive Pulmonary Disease In People Exposed To Wood Smoke. PREPOCOL: A Population Based Study
Type: Scientific Abstract
Category: 06.03 - COPD: Epidemiology (CP/EOH)
Authors: C.A. Torres-Duque1, A. Caballero2, M. Gonzalez-Garcia1, C. Jaramillo3, D. Maldonado1; 1Fundacion Neumologica Colombiana - Bogota/CO, 2Clinica Reina Sofia - Bogota/CO, 3Fundación Clinica Shaio - Bogota/CO
Rationale. Forty percent of the world population use solid fuels (charcoal or biomass), especially wood, for cooking or heating. The majority of the studies relating domiciliary exposure to wood smoke (WS) with chronic obstructive pulmonary disease (COPD) have been case-control or case series studies. The aim of this study was to describe the prevalence and to characterize the people with COPD related with WS.
Methods. Analytical cross-sectional, probabilistic, population-based study (PREPOCOL) in people older than 40 years in five Colombian cities. Each subject answered a respiratory questionnaire, which included questions on WS exposure, and performed spirometry. COPD was defined by a FEV1/FVC postbronchodilator <70%. Subjects were separated in three groups: 1) Exposed to WS - Never tobacco smokers (WS group); 2) Exposed to tobacco smoke - Never exposed to WS (TS group); 3) Exposed to both wood and tobacco smoke (MS group). Student t, χ2 and logistic regression were used.
Results. We included 5539 subjects distributed according to exposure: WS:30,9%, TS:18,7%, MS:29,8%, and none:20,6%. The overall prevalence of COPD was 8.9% and according to exposure: WS:6,7%, TS:7,8%, and MS:16,0% (p<0,001). Fifty-three percent of people with COPD had both wood and tobacco smoke exposure. The prevalence of COPD was higher as length of WS exposure increased (figure 1). After adjusted, WS exposure ≥10 years was a risk factor for COPD (overall: OR:1.50, CI95%: 1,22,86 [p:<0,001], female: OR:1,84, CI95%: 1,31,60 [p:<0,001], male: OR:1,53, CI95%: 1,08,18 [p:0,017]). In comparison with TS and MS, people with WS COPD were predominantly female and had lower height and higher body mass index. COPD subjects with both wood and tobacco exposure had significantly lower FEV1 and FEV1/FVC and more frequently cough (54,1%)(p=0.014) and phlegm (52,1%)(p<0,001) than those exposed to only WS or TS. Conclusions. In this population-based study from a developing country, the exposure to WS was more frequent than tobacco smoke and was an independent risk factor for COPD, both in women and men. The prevalence of COPD was significantly higher in people exposed to both wood and tobacco smoke. Similarly, subjects with COPD exposed to both wood and tobacco smoke had more symptoms and more severe obstruction than those exposed to only WS or TS. An additive effect of wood and tobacco is apparent for increasing the prevalence of COPD in people exposed and the frequency of symptoms in people with COPD.