Trends in the mortality of chronic obstructive pulmonary disease in Taiwan, 1981-2002

Abstract

Background and purpose: The reported prevalence, morbidity and mortality of chronic obstructive pulmonary disease (COPD) varies in different countries due to actual differences and to differences in classification criteria. This study analyzed the trends in COPD mortality and its rank among leading causes of death in Taiwan.

Methods: Using national mortality and population data, we identified COPD as a cause of death according to codes 490 (bronchitis, not specified as acute or chronic), 491 (chronic bronchitis), 492 (emphysema) as has been officially calculated previously in Taiwan, and by adding code 496 (chronic airway obstruction, not elsewhere classified) of the ninth revision of the International Classification of Diseases (ICD-9). We calculated crude, age-adjusted and age-specific mortality rates and analyzed the rank of COPD as a cause of death for the period from 1981 to 2002.

Results: Crude COPD mortality was unchanged from 1981 to 1993 at 8.26 to 8.47 deaths per 100,000 population, and steadily increased thereafter to 17.88 per 100,000 in 2002. After age standardization, mortality decreased from 8.26 to 4.91 per 100,000 population from 1981 to 1993 and then increased to a peak of 7.36 per 100,000 in 1999. This increase was due to greater increase in mortality in men. COPD mortality decreased steadily throughout the study period in those younger than 65 years while in older groups, it decreased during 1981-1991 and then increased. ICD-9 code A323 (including codes 490-493) has been previously used in official mortality data for asthma, chronic bronchitis and emphysema in Taiwan without inclusion of a specific code for chronic airway obstruction. According to our analysis, this method underestimated two-thirds of real overall mortality due to COPD and asthma. By including COPD and asthma, the obstructive airway disease category increased from 11th to sixth as a cause of death in 2002.

Conclusions: In Taiwan, mortality rates for COPD decreased from 1981 to 1993 and increased thereafter, which is largely attributable to increased rates in men. COPD is increasingly important and a leading cause of death in Taiwan.