**3.1.1 Cigarette smoking**

Cigarette smoking is the most significant and predictable risk factor in pathogenesis of COPD. Almost 80% of individuals who have COPD and 80% who die from COPD in the

Current Overview of COPD with Special Reference to Emphysema 121

population(Buist et al,2007). Increase in smoking among women has diminished the difference among gender prevalence. Mortality may be peaking among men in the United States but, among women, mortality continues to rise and deaths from COPD among women now even exceeds those among men (Mannino et al.,2002,Silverman et al.,2000 as

Accelerated loss of lung function has been noted among asthma patients(Lange et al.,1998; Peat et al.,1989 as cited in Shapiro SD,2010). Functional changes in both the small airways and the alveolar parenchyma have been reported. Many individuals have bronchial inflammation with features of both asthma and chronic bronchitis/emphysema( Gelb &

Morbidity and mortality rates have been shown to be inversely related to socioeconomic status(U.S. Department of Health and Human Resources,1984; Mannino & Buist,2007). Relative lack of awareness,diagnostic and therapeutic facilities and poorer health conditions

Impairment in early lung growth and development appears to increase the risk of development of COPD(Weiss & Ware,1996 as cited in Shapiro SD,2010). Maternal smoking, low-birth weight and recurrent childhood respiratory infections have been associated with higher incidence of adulthood COPD.(Marossy et al.,2007; Shaheen,1998 as cited in Shapiro

Observational studies strongly suggest that dietary factors, such as a higher intake of vitamin C and other antioxidants(carotenoids,Vitamin E,lutein, flavanoids) are significantly associated with better lung function(ATS,2010). Some dietary elements like fruits and vegetables(antioxidants), fish(omega-3 polyunsaturated fatty acids) and Vitamin D seem protective while processed foods like cured meats(nitrites) may be deleterious for lung

Pulmonary tuberculosis can lead to scarring and accelerated decline in lung function(Hnizdo et al.,2000 as cited in Shapiro SD,2010). Some population-based surveys(PLATINO and PREPOCOL) reported strong association between previous tuberculosis and a greater risk of COPD(Caballero et al.,2008; Menezes et al.,2007 as cited in

Emphysema is prevalent in approximately 2% of intravenous drugs abusers which can be attributed to pulmonary vascular damage possibly from the insoluble filler. Bullous cysts

may in part be connected to the socioeconomic status of the affected population.

cited in Shapiro SD,2010).

Zamel,2000 as cited in Shapiro SD,2010).

**3.1.6 Socioeconomic status** 

**3.1.7 Developmental events** 

SD,2010)

**3.1.8 Dietary factors** 

**3.1.9 Tuberculosis** 

Shapiro SD,2010).

function preservation(ATS,2010).

**3.1.10 Intravenous drug abuse** 

**3.1.5 Asthma** 

United States are smokers (Mannino et al.,2002 as cited in Shapiro SD,2010). The estimated fraction of COPD mortality attributable to smoking was 54% for men 30–69 years of age and 52% for men 70 years of age or older (Ezzati & Lopez,2003 as cited in ATS,2010). There is a consistent exposure–response relationship which is demonstrated in evidence from cohort studies fulfilling the causal criterion of temporality (exposure preceding onset of disease). Although only 15% of smokers have clinically significant COPD, smoking leads to a predictable dose-dependent loss of lung function in pre-symptomatic phase which accelerates with age and has prognostic implications (Rennard & Vestbo,2006 as cited in Shapiro SD,2010). Smoking has supra-additive effect in worsening lung function and prognosis when combined with other risk factors like A1PI deficiency or occupational exposures(Silverman et al.,2009 as cited in Shapiro SD,2010).
