Recent studies have shown that air pollution is a risk factor for hospitalization for congestive heart failure (CHF). However, there is limited evidence to suggest what subpopulations are at greater risk from air pollution. This study was undertaken to examine the modifying effect of specific secondary diagnosis (including hypertension, diabetes, dysrhythmia, and chronic obstructive pulmonary disease) on the relationship between hospital admissions for CHF and ambient air pollutants. Hospital admissions for CHF and ambient air pollution data for Taipei were obtained for the period from 1996 to 2005. The relative risk of hospital admission was estimated using a case-crossover approach. None of the secondary diagnosis we examined (hypertension, diabetes, dysrhythmia, and chronic obstructive pulmonary disease (COPD)) showed much evidence of effect modification.
