Trends in socioeconomic status-related differences in mortality among people with chronic obstructive pulmonary disease

Rationale: Previous studies have demonstrated that people of higher socioeconomic status (SES) have better chronic obstructive pulmonary disease (COPD) health outcomes than those of lower SES. Mortality of people with COPD has decreased over the last decade; however, it is not known if all individuals with COPD have benefitted equally.

Objective: The objective of the current study was to examine the impact of SES on mortality trends of individuals with COPD.

Methods: We conducted a population-based study using health administrative data from Ontario, Canada, between 1996/7 and 2011/12. Individuals with COPD were identified using a previously validated case definition. SES was determined using average household income of the individual's neighborhood as per the Canadian Census. Trends in standardized COPD mortality rates among different SES quintiles were observed over time.

Measurements and main results: Overall, age- and sex-standardized mortality of people with COPD decreased from 5.7% (95% confidence interval [CI], 5.5-5.8) in 1996/7 to 3.7% (95% CI, 3.6-3.8) in 2011/12, representing a 35% relative decrease. The mortality difference between the lowest and highest income quintiles increased from 67 per 10,000 individuals in 1996/7 to 86 per 10,000 individuals in 2011/12, representing a 28% relative increase (P < 0.001).

Conclusions: Mortality in people with COPD has decreased faster in people with the highest compared with the lowest SES, causing increased disparity between rich and poor. Further study and strategies are needed to explore and address factors responsible for this increasing disparity in the COPD population.