Figure 4 .

– Age-specific death rates for pulmonary hypertension as a contributing cause of death and trend lines among individuals of all ages, by six age groups: United States, 2001-2010. The National Vital Statistics System was used to ascertain deaths due to pulmonary hypertension, which were considered those with decedents having ICD-10 codes I27.0, I27.2, I27.8, or I27.9 reported as any contributing cause of death (ie, any of the possible 20 conditions, including the underlying cause of death). ^aRates are per 100,000 population and age-specific death rates were calculated for each of six age groups; ^ball age-specific trend lines are compared with the referent age group of 0 to 12 mo, P < .05. Both parallelism and coincident comparison of trend lines were rejected. See Table 9 for additional data. See Figure 2 legend for expansion of abbreviation.